Materiały źródłowe

• #1 Poison ivy rash – Symptoms and causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/poison-ivy/symptoms-causes/syc-20376485

  Poison ivy rash is caused by an allergic reaction to an oily resin called urushiol (u-ROO-she-ol). This oily resin is very sticky, so it easily attaches to your skin, clothing, tools, equipment and pet’s fur. […] Poison ivy rash is caused by an allergic reaction to an oily resin called urushiol. It’s found in poison ivy, poison oak and poison sumac. The reaction usually develops 12 to 48 hours after exposure and lasts two to three weeks. […] The severity of the rash depends on the amount of urushiol that gets on your skin.

• #2 Urushiol-induced contact dermatitis – Wikipedia

  https://en.wikipedia.org/wiki/Urushiol-induced_contact_dermatitis

  Urushiol-induced contact dermatitis is caused by contact with a plant or any other object containing urushiol oil. The oil adheres to almost anything with which it comes in contact, such as towels, blankets, clothing, and landscaping tools. Clothing or other materials that touch the plant and then, before being washed, touch the skin are common causes of exposure. […] Urushiol is fat-soluble, penetrating the stratum corneum of the skin, then binding to Langerhans cells in the epidermis. The affected cells then migrate to lymph nodes, where T cells become activated, then return to the skin where they stimulate an urushiol-activated dermatitis. The toxic effect is indirect, mediated by an induced immune response. The oxidized urushiols act as haptens, chemically reacting with, binding to, and changing the shape of integral membrane proteins on exposed skin cells.

• #3 Poison Ivy Rash, Poison Oak, Poison Sumac: Symptoms, Causes & Treatment

  https://my.clevelandclinic.org/health/diseases/10655-poison-plants-poison-ivy–poison-oak–poison-sumac

  Poison ivy, poison oak and poison sumac produce urushiol oil. Almost everyone is allergic to it. The oil causes an allergic reaction when it touches your skin. The itchy rash that develops is a type of allergic contact dermatitis. […] Up to 90% of people who come into contact with poison ivy oil develop an itchy rash. You dont have to be exposed to much: 50 micrograms (g) of urushiol an amount smaller than a grain of salt is enough to cause a reaction. […] Poison ivy symptoms almost always include: An itchy skin rash. Redness and swelling. Blisters. […] Depending on your skins sensitivity, a rash may develop within a few hours or a few days after initial contact with urushiol oil. […] The intensity of the itching can vary, and some people may develop one or two small rashes while others develop rashes all over their bodies.

• #4 3 Causes of Poison Ivy & How To Treat It | Vujevich Dermatology

  https://www.vucare.com/2019/09/20/causes-of-poison-ivy/

  Poison ivy rash is caused by urushiol oil. Eighty to 90 percent of people exposed to 50 micrograms of urushiol (thats less than one grain of table salt!) develop a rash. But, some people see no reaction from contact with urushiol oil. […] Sensitivity to urushiol oil can change over your lifetime. Children who developed the rash as a child may completely lose their sensitivity to the oil. Likewise, adults who never had the rash as a child may develop a sensitivity to the oil.

• #5 Toxicodendron Toxicity – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK557866/

  Acute allergic dermatitis is caused by contact with bruised or broken parts of plants within the Toxicodendron species. Urushiol is the primary inciting compound causing the release of local cytokines and inflammatory mediators that initiate the process of sensitization. […] Initial exposure results in pruritus and erythema, followed by a papulovesicular eruption, edema, and oozing within 10 to 14 days. Symptoms of re-exposure are more acute and appear in 24 to 72 hours. […] Sensitization and reexposure are mediated by a type IV cell-mediated hypersensitivity reaction. Langerhans cells, or antigen-presenting cells (APCs), and other acute inflammatory mediators are activated, initiating a local response. APCs break down urushiol into antigens, which either combine with major histocompatibility complex II (MHC II) or are exposed on the surface of APCs. […] Activation of T cells on initial exposure results in the production of CD4 and CD8 T cells sensitive to urushiol, which then activate a more robust immune response on repeat exposure to the offending agent.

• #6 Poison ivy: Scratchin’ like a hound? – Harvard Health

  https://www.health.harvard.edu/blog/poison-ivy-scratchin-like-a-hound-202208172804

  „When I was growing up, my parents told me you could only get poison ivy if you touched the leaves when they were red and shiny,” says Dr. Abigail Waldman, a dermatologist at Harvard-affiliated Brigham and Women’s Hospital. That is not true, she emphasizes. Urushiol, the oily resin that triggers an allergic reaction, is found throughout the year in all parts of the plant: the leaves, stems, bark, fruit, and roots. […] You can develop symptoms a red, itchy rash that sometimes features blisters from four hours to four days after you’re exposed to urushiol. Why the long lag time? The rash caused by poison ivy is a form of allergic contact dermatitis. It’s mediated by T cells, the immune cells that recognize and attack foreign substances in this case, skin proteins that react with urushiol. […] „T cells take 24 to 96 hours to ramp up in the body, which is why this is also known as a delayed-type hypersensitivity reaction,” says Dr. Jeff Yu, assistant professor of dermatology at Harvard Medical School. Symptoms take longer to show up after your first exposure to poison ivy. „But once your body has been exposed and reacted several times, it tends to show up faster because your body 'remembers’ the rashes and has T cells ready to go,” he explains.

• #7 Urushiol-induced contact dermatitis – Wikipedia

  https://en.wikipedia.org/wiki/Urushiol-induced_contact_dermatitis

  Urushiol-induced contact dermatitis is caused by contact with a plant or any other object containing urushiol oil. The oil adheres to almost anything with which it comes in contact, such as towels, blankets, clothing, and landscaping tools. Clothing or other materials that touch the plant and then, before being washed, touch the skin are common causes of exposure. […] Urushiol is fat-soluble, penetrating the stratum corneum of the skin, then binding to Langerhans cells in the epidermis. The affected cells then migrate to lymph nodes, where T cells become activated, then return to the skin where they stimulate an urushiol-activated dermatitis. The toxic effect is indirect, mediated by an induced immune response. The oxidized urushiols act as haptens, chemically reacting with, binding to, and changing the shape of integral membrane proteins on exposed skin cells.

• #8 Poison Ivy Immunology

  https://www.bio.umass.edu/micro/immunology/poisoniv.htm

  If urushiol is washed off the skin within an hour or so, the reaction can be largely prevented. However, if left on the skin, some diffuses through the skin, where it is metabolized to quinone derivatives. These form covalent complexes with skin proteins such as keratin. These complexes appear foreign to the immune system, which therefore attacks them.

• #9 NC DNA Day » Poison Ivy

  http://ncdnaday.org/2020/04/poison-ivy/

  Urushiol is actually not one moleculeits a mixture of molecule that all have one piece in common. […] Exposure to the oil causes a nasty, itchy, oozy red and often quite painful rash. […] Urushiol is an incredibly sticky oil made of a variety of similar molecules, the most common of which is pentadecacatechol (seen above). Its harmless by itself, but when it reacts with proteins in skin, it can generate an immune response. […] Poison ivy rash is caused by delayed type hypersensitivity, a process where special immune cells called T-cells generate an allergic response. […] When this happens, the harmless oil changes the shape of skin proteins to make a new antigen (a substance the immune system can interact with). […] T-cells in the skin kick into high gear and try to defeat the new antigen. […] These proteins lead to swelling, itch, redness, and tissue damage. A doctor would identify this rash as contact dermatitis.

• #10 Poison ivy-induced dermatitis on NativeSkin® | Genoskin

  https://genoskin.com/poison-ivy-induced-dernmatitis-on-nativeskin/

  Two types of mechanism of action can be observed after contact with poison ivy or one of the other Toxicodendron incriminated. Urushiol can act both as an irritant and an allergen. […] The most common is an allergic contact dermatitis which is a type IV hypersensitivity reaction. Urushiol can penetrate the skin within approximately an hour if not washed. […] When urushiol catechols penetrate the skin, upon oxidation, they are converted into a quinine intermediate to become an hapten. […] They bind with Langerhans cells (antigen-presenting cells) which lead to the activation of immune system mediators. […] T-cells are involved in the pathogenicity resulting in sensitization. Subsequent contact will produce a quicker reaction but the pathogenicity will also vary on the duration and the amount of exposure.

• #11 A poison ivy primer | Smithsonian Institution

  https://www.si.edu/stories/poison-ivy-primer

  In humans, contact with poison ivy causes a reaction known as a cell-mediated immune response. Basically, as Pell explains, the urushiol binds to proteins in the membrane of your skin cells and interferes with their ability to communicate with other cells. It tricks your immune system into regarding your own skin cells as foreign. Urushiol is not an irritant burning your skin, Pell adds. The rash is actually a result of your own immune system attacking your own skin cells. […] Ten to 15 percent of people are immune to poison ivy and will never have a rash. Repeated contact however will not give you immunity, in fact just the opposite, Pell explains. The rashes get worse and worse as your immune system gets better and better at recognizing urushiol.

• #12 Toxicodendron Toxicity – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK557866/

  Acute allergic dermatitis is caused by contact with bruised or broken parts of plants within the Toxicodendron species. Urushiol is the primary inciting compound causing the release of local cytokines and inflammatory mediators that initiate the process of sensitization. […] Initial exposure results in pruritus and erythema, followed by a papulovesicular eruption, edema, and oozing within 10 to 14 days. Symptoms of re-exposure are more acute and appear in 24 to 72 hours. […] Sensitization and reexposure are mediated by a type IV cell-mediated hypersensitivity reaction. Langerhans cells, or antigen-presenting cells (APCs), and other acute inflammatory mediators are activated, initiating a local response. APCs break down urushiol into antigens, which either combine with major histocompatibility complex II (MHC II) or are exposed on the surface of APCs. […] Activation of T cells on initial exposure results in the production of CD4 and CD8 T cells sensitive to urushiol, which then activate a more robust immune response on repeat exposure to the offending agent.

• #13 Urushiol-induced contact dermatitis – Wikipedia

  https://en.wikipedia.org/wiki/Urushiol-induced_contact_dermatitis

  Urushiol-induced contact dermatitis is caused by contact with a plant or any other object containing urushiol oil. The oil adheres to almost anything with which it comes in contact, such as towels, blankets, clothing, and landscaping tools. Clothing or other materials that touch the plant and then, before being washed, touch the skin are common causes of exposure. […] Urushiol is fat-soluble, penetrating the stratum corneum of the skin, then binding to Langerhans cells in the epidermis. The affected cells then migrate to lymph nodes, where T cells become activated, then return to the skin where they stimulate an urushiol-activated dermatitis. The toxic effect is indirect, mediated by an induced immune response. The oxidized urushiols act as haptens, chemically reacting with, binding to, and changing the shape of integral membrane proteins on exposed skin cells.

• #14 From leaf to itch — Harvard Gazette

  https://news.harvard.edu/gazette/story/2016/09/from-leaf-to-itch/

  Researchers from Harvard Medical School and Boston Childrens Hospital are among the first to trace poison ivys molecular path, following the effect from leaf to burning itch and pointing a potentially soothing way forward. […] Investigators led by Assistant Professor of Microbiology and Immunobiology Florian Winau were able to do what previous teams hadnt managed: illuminate the role of a key molecule called CD1a in a chain reaction that begins when the shiny leaf touches the skin. […] The findings, published last month in Nature Immunology, took advantage of mice engineered to produce the molecule by colleagues at Kyoto University, which enabled observation of the entire inflammatory pathway for the first time. […] When urushiol comes into contact with Langerhans cells in the skin, the Langerhans cells load urushiol on CD1a molecules that activate the immune systems T cells. The T cells produce interleukin 17 and interleukin 22, which cause inflammation and itchiness. […] Researchers eased the rash experimentally by using an antibody that interfered with communication between the CD1a molecule and T cells.

• #15 Toxicodendron Toxicity – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK557866/

  Acute allergic dermatitis is caused by contact with bruised or broken parts of plants within the Toxicodendron species. Urushiol is the primary inciting compound causing the release of local cytokines and inflammatory mediators that initiate the process of sensitization. […] Initial exposure results in pruritus and erythema, followed by a papulovesicular eruption, edema, and oozing within 10 to 14 days. Symptoms of re-exposure are more acute and appear in 24 to 72 hours. […] Sensitization and reexposure are mediated by a type IV cell-mediated hypersensitivity reaction. Langerhans cells, or antigen-presenting cells (APCs), and other acute inflammatory mediators are activated, initiating a local response. APCs break down urushiol into antigens, which either combine with major histocompatibility complex II (MHC II) or are exposed on the surface of APCs. […] Activation of T cells on initial exposure results in the production of CD4 and CD8 T cells sensitive to urushiol, which then activate a more robust immune response on repeat exposure to the offending agent.

• #16 Poison Ivy and the Immune System | HowStuffWorks

  https://science.howstuffworks.com/life/botany/poison-ivy2.htm

  The allergic reaction to poison ivy is known as delayed hypersensitivity. Unlike immediate hypersensitivity, which causes an allergic reaction within minutes of exposure to an antigen, delayed hypersensitivity reactions don’t emerge for several hours or even days after the exposure. […] Most people don’t have a reaction the first time they touch poison ivy, but develop an allergic reaction after repeated exposure. Everyone has a different sensitivity, and therefore a slightly different reaction, to poison ivy. Sensitivity usually decreases with age and with repeat exposures to the plant.

• #17 From leaf to itch — Harvard Gazette

  https://news.harvard.edu/gazette/story/2016/09/from-leaf-to-itch/

  Researchers from Harvard Medical School and Boston Childrens Hospital are among the first to trace poison ivys molecular path, following the effect from leaf to burning itch and pointing a potentially soothing way forward. […] Investigators led by Assistant Professor of Microbiology and Immunobiology Florian Winau were able to do what previous teams hadnt managed: illuminate the role of a key molecule called CD1a in a chain reaction that begins when the shiny leaf touches the skin. […] The findings, published last month in Nature Immunology, took advantage of mice engineered to produce the molecule by colleagues at Kyoto University, which enabled observation of the entire inflammatory pathway for the first time. […] When urushiol comes into contact with Langerhans cells in the skin, the Langerhans cells load urushiol on CD1a molecules that activate the immune systems T cells. The T cells produce interleukin 17 and interleukin 22, which cause inflammation and itchiness. […] Researchers eased the rash experimentally by using an antibody that interfered with communication between the CD1a molecule and T cells.

• #18 Poison Ivy and the Immune System | HowStuffWorks

  https://science.howstuffworks.com/life/botany/poison-ivy2.htm

  The rash caused by poison ivy often is red and sometimes causes blisters. […] But when urushiol from the poison ivy plant touches the skin, it instigates an immune response, called dermatitis, to what would otherwise be a harmless substance. […] Here’s how the poison ivy response occurs: Urushiol makes its way down through the skin, where it is metabolized, or broken down. Immune cells called T lymphocytes (or T-cells) recognize the urushiol derivatives as a foreign substance, or antigen. They send out inflammatory signals called cytokines, which bring in white blood cells. Under orders from the cytokines, these white blood cells turn into macrophages. The macrophages eat foreign substances, but in doing so they also damage normal tissue, resulting in the skin inflammation that occurs with poison ivy.

• #19 Poison Ivy Immunology

  https://www.bio.umass.edu/micro/immunology/poisoniv.htm

  The poison ivy plant and its relatives are common throughout the United States. Poison ivy leaves are coated with a mixture of chemicals called urushiol. When people get urushiol on their skin, it causes an allergic contact dermatitis. This is a T cell-mediated immune response, also called delayed hypersensitivity, in which the body’s immune system recognizes as foreign, and attacks, the complex of urushiol-derivatives with skin proteins. […] The irony is that urushiol, in the absence of the immune attack, would be harmless. […] Delayed hypersensitivity does not start to be noticeable until several hours to a full day after exposure to the antigen. It may last for over a week. T lymphocytes recognize the foreign substances, usually after the antigen is eaten, degraded, and presented (in pieces) by so-called antigen-presenting cells such as Langerhans cells in the skin, or macrophages. Urushiol metabolites are presented by this and other mechanisms. The T lymphocytes pour out inflammatory signal substances called cytokines. These call in armies of white blood cells called monocytes, which become macrophages. The macrophages become activated by the cytokines and attack everything in the vicinity, and can cause severe tissue damage.

• #20 Poison Ivy and the Immune System | HowStuffWorks

  https://science.howstuffworks.com/life/botany/poison-ivy2.htm

  The rash caused by poison ivy often is red and sometimes causes blisters. […] But when urushiol from the poison ivy plant touches the skin, it instigates an immune response, called dermatitis, to what would otherwise be a harmless substance. […] Here’s how the poison ivy response occurs: Urushiol makes its way down through the skin, where it is metabolized, or broken down. Immune cells called T lymphocytes (or T-cells) recognize the urushiol derivatives as a foreign substance, or antigen. They send out inflammatory signals called cytokines, which bring in white blood cells. Under orders from the cytokines, these white blood cells turn into macrophages. The macrophages eat foreign substances, but in doing so they also damage normal tissue, resulting in the skin inflammation that occurs with poison ivy.

• #21 Poison Ivy Immunology

  https://www.bio.umass.edu/micro/immunology/poisoniv.htm

  The poison ivy plant and its relatives are common throughout the United States. Poison ivy leaves are coated with a mixture of chemicals called urushiol. When people get urushiol on their skin, it causes an allergic contact dermatitis. This is a T cell-mediated immune response, also called delayed hypersensitivity, in which the body’s immune system recognizes as foreign, and attacks, the complex of urushiol-derivatives with skin proteins. […] The irony is that urushiol, in the absence of the immune attack, would be harmless. […] Delayed hypersensitivity does not start to be noticeable until several hours to a full day after exposure to the antigen. It may last for over a week. T lymphocytes recognize the foreign substances, usually after the antigen is eaten, degraded, and presented (in pieces) by so-called antigen-presenting cells such as Langerhans cells in the skin, or macrophages. Urushiol metabolites are presented by this and other mechanisms. The T lymphocytes pour out inflammatory signal substances called cytokines. These call in armies of white blood cells called monocytes, which become macrophages. The macrophages become activated by the cytokines and attack everything in the vicinity, and can cause severe tissue damage.

• #22 Mechanisms of Itch in Poison Ivy-Induced Allergic Contact Dermatitis – Boyi Liu

  https://grantome.com/index.php/grant/NIH/R21-AR070554-01

  Allergic contact dermatitis (ACD) is a common skin condition triggered by environmental or occupational allergens. In the US, the most common ACD is caused by contact with poison ivy with at least 10 million cases each year. The major clinical manifestations of poison ivy-induced ACD are skin rashes, swelling, and intense and persistent itch (pruritus), followed by the appearance of vesicles and bullae in severe cases. Antihistamines are generally ineffective for treating the pruritus associated with ACD. Recent studies demonstrated that proinflammatory cytokines and chemokines, such as IL-31, TSLP and CXCL10 are endogenous pruritogens and activate corresponding receptors expressed in primary sensory neurons to produce pruritus. IL-33 is an epithelial cell-derived proinflammatory cytokine, and signals via receptor ST2, which is highly expressed on Th2 cells and various types of innate immune cells. Recent evidence demonstrated the involvement of IL-33 in allergic skin diseases. In our pilot studies, mouse transcriptome microarray showed that IL-33 is significantly increased in the inflamed skin of mice with urushiol-induced ACD.

• #23 Mechanisms of Itch in Poison Ivy-Induced Allergic Contact Dermatitis – Boyi Liu

  https://grantome.com/index.php/grant/NIH/R21-AR070554-01

  Therefore, our central hypothesis is that IL-33 acts via ST2 expressed in peripheral sensory neurons to produce pruritus, and that blocking IL-33/ST2 and other related endogenous pruritic pathways is effective against pruritus caused by urushiol-induced ACD. […] Successful completion of the work proposed here will 1) establish a link between IL-33 and poison ivy-induced ACD, 2) reveal a previously unrecognized interaction between IL-33 and primary sensory neurons, and 3) identify major pruritogens that cause the intense and persistent pruritus associated with poison ivy-induced ACD. […] This proposal aims to address how to treat the severe pruritus in poison ivy-induced ACD by identifying and targeting specific endogenous pruritogens and signaling pathways.

• #24 Toxicodendron Toxicity – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK557866/

  Acute allergic dermatitis is caused by contact with bruised or broken parts of plants within the Toxicodendron species. Urushiol is the primary inciting compound causing the release of local cytokines and inflammatory mediators that initiate the process of sensitization. […] Initial exposure results in pruritus and erythema, followed by a papulovesicular eruption, edema, and oozing within 10 to 14 days. Symptoms of re-exposure are more acute and appear in 24 to 72 hours. […] Sensitization and reexposure are mediated by a type IV cell-mediated hypersensitivity reaction. Langerhans cells, or antigen-presenting cells (APCs), and other acute inflammatory mediators are activated, initiating a local response. APCs break down urushiol into antigens, which either combine with major histocompatibility complex II (MHC II) or are exposed on the surface of APCs. […] Activation of T cells on initial exposure results in the production of CD4 and CD8 T cells sensitive to urushiol, which then activate a more robust immune response on repeat exposure to the offending agent.

• #25 Poison ivy, oak, and sumac: What does the rash look like?

  https://www.aad.org/public/everyday-care/itchy-skin/poison-ivy/what-rash-looks-like

  While it may look like the rash is spreading, what’s most likely happening is that you’re developing one or more new rashes. This happens because you either got urushiol (the oil from these plants that causes the rash) on more than one area of your skin. […] If your new rash appears near the current rash, it can look like the rash is spreading. […] Many people also mistakenly believe that when they touch their rash, they can spread the rash from one part of their body to another. You cannot spread the rash. […] How long you have a rash depends on whether you’ve had a rash from one of these plants before. Here’s the general rule: Previous rash from poison ivy, oak, or sumac: The rash tends to last 1 to 14 days before it clears on its own. […] Never had a rash from poison ivy, oak, or sumac: You can have a rash for 21 days or longer before it goes away.

• #26 Poison ivy: Scratchin’ like a hound? – Harvard Health

  https://www.health.harvard.edu/blog/poison-ivy-scratchin-like-a-hound-202208172804

  „When I was growing up, my parents told me you could only get poison ivy if you touched the leaves when they were red and shiny,” says Dr. Abigail Waldman, a dermatologist at Harvard-affiliated Brigham and Women’s Hospital. That is not true, she emphasizes. Urushiol, the oily resin that triggers an allergic reaction, is found throughout the year in all parts of the plant: the leaves, stems, bark, fruit, and roots. […] You can develop symptoms a red, itchy rash that sometimes features blisters from four hours to four days after you’re exposed to urushiol. Why the long lag time? The rash caused by poison ivy is a form of allergic contact dermatitis. It’s mediated by T cells, the immune cells that recognize and attack foreign substances in this case, skin proteins that react with urushiol. […] „T cells take 24 to 96 hours to ramp up in the body, which is why this is also known as a delayed-type hypersensitivity reaction,” says Dr. Jeff Yu, assistant professor of dermatology at Harvard Medical School. Symptoms take longer to show up after your first exposure to poison ivy. „But once your body has been exposed and reacted several times, it tends to show up faster because your body 'remembers’ the rashes and has T cells ready to go,” he explains.

• #27 Toxicodendron Toxicity – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK557866/

  Acute allergic dermatitis is caused by contact with bruised or broken parts of plants within the Toxicodendron species. Urushiol is the primary inciting compound causing the release of local cytokines and inflammatory mediators that initiate the process of sensitization. […] Initial exposure results in pruritus and erythema, followed by a papulovesicular eruption, edema, and oozing within 10 to 14 days. Symptoms of re-exposure are more acute and appear in 24 to 72 hours. […] Sensitization and reexposure are mediated by a type IV cell-mediated hypersensitivity reaction. Langerhans cells, or antigen-presenting cells (APCs), and other acute inflammatory mediators are activated, initiating a local response. APCs break down urushiol into antigens, which either combine with major histocompatibility complex II (MHC II) or are exposed on the surface of APCs. […] Activation of T cells on initial exposure results in the production of CD4 and CD8 T cells sensitive to urushiol, which then activate a more robust immune response on repeat exposure to the offending agent.

• #28 Poison ivy, oak, and sumac: What does the rash look like?

  https://www.aad.org/public/everyday-care/itchy-skin/poison-ivy/what-rash-looks-like

  While it may look like the rash is spreading, what’s most likely happening is that you’re developing one or more new rashes. This happens because you either got urushiol (the oil from these plants that causes the rash) on more than one area of your skin. […] If your new rash appears near the current rash, it can look like the rash is spreading. […] Many people also mistakenly believe that when they touch their rash, they can spread the rash from one part of their body to another. You cannot spread the rash. […] How long you have a rash depends on whether you’ve had a rash from one of these plants before. Here’s the general rule: Previous rash from poison ivy, oak, or sumac: The rash tends to last 1 to 14 days before it clears on its own. […] Never had a rash from poison ivy, oak, or sumac: You can have a rash for 21 days or longer before it goes away.

• #29 Toxicodendron Toxicity – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK557866/

  Acute allergic dermatitis is caused by contact with bruised or broken parts of plants within the Toxicodendron species. Urushiol is the primary inciting compound causing the release of local cytokines and inflammatory mediators that initiate the process of sensitization. […] Initial exposure results in pruritus and erythema, followed by a papulovesicular eruption, edema, and oozing within 10 to 14 days. Symptoms of re-exposure are more acute and appear in 24 to 72 hours. […] Sensitization and reexposure are mediated by a type IV cell-mediated hypersensitivity reaction. Langerhans cells, or antigen-presenting cells (APCs), and other acute inflammatory mediators are activated, initiating a local response. APCs break down urushiol into antigens, which either combine with major histocompatibility complex II (MHC II) or are exposed on the surface of APCs. […] Activation of T cells on initial exposure results in the production of CD4 and CD8 T cells sensitive to urushiol, which then activate a more robust immune response on repeat exposure to the offending agent.

• #30 Poison ivy rash – Symptoms and causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/poison-ivy/symptoms-causes/syc-20376485

  Poison ivy rash is caused by an allergic reaction to an oily resin called urushiol (u-ROO-she-ol). This oily resin is very sticky, so it easily attaches to your skin, clothing, tools, equipment and pet’s fur. […] Poison ivy rash is caused by an allergic reaction to an oily resin called urushiol. It’s found in poison ivy, poison oak and poison sumac. The reaction usually develops 12 to 48 hours after exposure and lasts two to three weeks. […] The severity of the rash depends on the amount of urushiol that gets on your skin.

• #31 Poison ivy: Scratchin’ like a hound? – Harvard Health

  https://www.health.harvard.edu/blog/poison-ivy-scratchin-like-a-hound-202208172804

  „When I was growing up, my parents told me you could only get poison ivy if you touched the leaves when they were red and shiny,” says Dr. Abigail Waldman, a dermatologist at Harvard-affiliated Brigham and Women’s Hospital. That is not true, she emphasizes. Urushiol, the oily resin that triggers an allergic reaction, is found throughout the year in all parts of the plant: the leaves, stems, bark, fruit, and roots. […] You can develop symptoms a red, itchy rash that sometimes features blisters from four hours to four days after you’re exposed to urushiol. Why the long lag time? The rash caused by poison ivy is a form of allergic contact dermatitis. It’s mediated by T cells, the immune cells that recognize and attack foreign substances in this case, skin proteins that react with urushiol. […] „T cells take 24 to 96 hours to ramp up in the body, which is why this is also known as a delayed-type hypersensitivity reaction,” says Dr. Jeff Yu, assistant professor of dermatology at Harvard Medical School. Symptoms take longer to show up after your first exposure to poison ivy. „But once your body has been exposed and reacted several times, it tends to show up faster because your body 'remembers’ the rashes and has T cells ready to go,” he explains.

• #32 Toxicodendron Contact Dermatitis: A Case Report and Brief Review

  https://pmc.ncbi.nlm.nih.gov/articles/PMC7733371/

  Contact dermatitis caused by the sap of plants from the Anacardiaceae family, including poison ivy, oak, and sumac, is among the most common skin conditions in the United States. […] Toxicodendron contact dermatitis (TCD) is a highly pruritic papulovesicular eruption that represents a Type-IV delayed hypersensitivity reaction triggered by contact with the sap of plants from the Anacardiaceae family, which includes poison ivy (the most common), oak, and sumac. […] Sap from the injured leaves, stems, and berries of these plants contain an oily resin called urushiol, to which 85 to 90 percent of adults are allergic. […] Exposure to urushiol can result in an intensely pruritic and potentially blistery rash that can persist for weeks regardless of treatment, and each additional exposure to urushiol can cause increasingly severe skin reactions.

• #33 Toxicodendron Contact Dermatitis: A Case Report and Brief Review

  https://pmc.ncbi.nlm.nih.gov/articles/PMC7733371/

  The combination of itching, the linear configuration of the lesions, and a history of recent exposure to the plant is essentially pathognomic. […] The rash and related symptoms can last a month or more, with or without treatment. […] Key to preventing TCD is the ability to recognize these plants and, thus, avoid contact with them. […] Once the immune system is triggered by the penetration of the oily resin, however, no amount of washing can help. […] While there is no entirely satisfactory treatment for TCD other than the tincture of time, longer-course glucocorticoid therapy, such as triamcinolone or prednisone, has been shown to be effective in relieving symptoms associated with TCD. […] The risks and benefits of all treatments, along with the understanding that the problem will eventually resolve on its own, with or without treatment, should always be discussed with each patient to assist the individual in making an informed decision regarding the treatment plan.

• #34 Allergic reactions caused by poison ivy | Gouvernement du Québec

  https://www.quebec.ca/en/health/health-issues/a-z/allergic-reactions-caused-by-poison-ivy

  When skin comes into contact with poison ivy sap, a painful allergic reaction called contact dermatitis or Rhus dermatitis may occur. […] The substance that causes this allergic reaction is urushiol, a compound in the poison ivy sap. […] About 9 in 10 people are sensitive to poison ivy sap. They react to even minute quantities of urushiol. […] The symptoms of an allergic reaction to poison ivy usually appear 24 to 48 hours after contact with the sap. […] The first sign of an allergic reaction to poison ivy is a strong itching with redness at the site of contact. […] The seriousness of an allergic reaction depends on: The persons degree of sensitivity, The amount of sap that comes into contact with the skin, The area of the body affected. […] The most serious allergic reactions affect areas of the body where the skin is thin, like the face and the genitals.

• #35 Poison ivy rash – Symptoms and causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/poison-ivy/symptoms-causes/syc-20376485

  Poison ivy rash is caused by an allergic reaction to an oily resin called urushiol (u-ROO-she-ol). This oily resin is very sticky, so it easily attaches to your skin, clothing, tools, equipment and pet’s fur. […] Poison ivy rash is caused by an allergic reaction to an oily resin called urushiol. It’s found in poison ivy, poison oak and poison sumac. The reaction usually develops 12 to 48 hours after exposure and lasts two to three weeks. […] The severity of the rash depends on the amount of urushiol that gets on your skin.

• #36 Poison ivy rash | Beacon Health System

  https://www.beaconhealthsystem.org/library/diseases-and-conditions/poison-ivy-rash?content_id=CON-20376467

  Poison ivy rash is caused by an allergic reaction to an oily resin called urushiol (u-ROO-she-ol). This oily resin is very sticky, so it easily attaches to your skin, clothing, tools, equipment and pet’s fur. […] Poison ivy rash is caused by an allergic reaction to an oily resin called urushiol. It’s found in poison ivy, poison oak and poison sumac. The severity of the rash depends on the amount of urushiol that gets on your skin. […] Even the smoke from burning poison ivy, poison oak and poison sumac can irritate or harm your nasal passages or lungs.

• #37

  https://tecnu.com/a/docs/guides-how-tos/how-does-poison-ivy-work?srsltid=AfmBOoqv72dIYb68j046WPatlguZLY967a5NzDeScxc7xd-YWoiYeXvm

  When urushiol touches the skin, it doesnt cause immediate symptoms. Instead, it begins to penetrate the skin, where it binds to proteins in the skin cells. This process transforms the skin cells into what your immune system identifies as a foreign substance, sparking an allergic reaction. The severity of the reaction can vary widely from one person to another, depending on their sensitivity and the amount of urushiol that comes into contact with the skin. […] How Does Poison Ivy Affect the Skin? Once urushiol touches your skin, it starts to penetrate almost immediately. Within 8 hours, you may begin to notice a red, swollen rash that can blister and become extremely itchy. The severity of the reaction depends on the amount of urushiol that contacts the skin and individual sensitivity. Surprisingly, only about 85% of people are allergic to urushiol, meaning that a small amount of the population won’t experience a rash, no matter how much they come into contact with the plant.

• #38 Allergic reactions caused by poison ivy | Gouvernement du Québec

  https://www.quebec.ca/en/health/health-issues/a-z/allergic-reactions-caused-by-poison-ivy

  When skin comes into contact with poison ivy sap, a painful allergic reaction called contact dermatitis or Rhus dermatitis may occur. […] The substance that causes this allergic reaction is urushiol, a compound in the poison ivy sap. […] About 9 in 10 people are sensitive to poison ivy sap. They react to even minute quantities of urushiol. […] The symptoms of an allergic reaction to poison ivy usually appear 24 to 48 hours after contact with the sap. […] The first sign of an allergic reaction to poison ivy is a strong itching with redness at the site of contact. […] The seriousness of an allergic reaction depends on: The persons degree of sensitivity, The amount of sap that comes into contact with the skin, The area of the body affected. […] The most serious allergic reactions affect areas of the body where the skin is thin, like the face and the genitals.

• #39 Everything you need to know about poison ivy | News | Des Moines University

  https://www.dmu.edu/blog/2019/08/everything-you-need-to-know-about-poison-ivy/

  Urushiol can transfer from the plant to something that a person then touches. For example, urushiol is oftentimes transferred from pets: Your dog walks through poison ivy, gets urushiol on its fur, you pet the dog, you get poison ivy. […] The amazing thing about urushiol is that it can remain allergenic on clothing for up to 10 years! That’s right you can get urushiol on your jeans, put them in a drawer and pull them out years later and still get a blistering rash from the leftover urushiol. […] A particularly cruel aspect of poison ivy is that the rash can take anywhere from 24 hours to seven days to develop. This leads to the misconception that the rash spreads. The timing with which poison ivy symptoms erupt depends on three things: The amount of urushiol involved, The thickness of the skin involved, The sensitivity of the person exposed.

• #40 A poison ivy primer | Smithsonian Institution

  https://www.si.edu/stories/poison-ivy-primer

  In humans, contact with poison ivy causes a reaction known as a cell-mediated immune response. Basically, as Pell explains, the urushiol binds to proteins in the membrane of your skin cells and interferes with their ability to communicate with other cells. It tricks your immune system into regarding your own skin cells as foreign. Urushiol is not an irritant burning your skin, Pell adds. The rash is actually a result of your own immune system attacking your own skin cells. […] Ten to 15 percent of people are immune to poison ivy and will never have a rash. Repeated contact however will not give you immunity, in fact just the opposite, Pell explains. The rashes get worse and worse as your immune system gets better and better at recognizing urushiol.

• #41 Poison ivy can work itchy evil on your skin — here’s how

  https://www.asbmb.org/asbmb-today/science/090821/how-poison-ivy-works

  Poison ivy is not poisonous. It carries an oily sap on its leaves and stems called urushiol, which is irritating to most peoples skin. In fact, 85% to 90% of people are allergic to poison ivys urushiol to some degree, while the rest lack sensitivity to this oil. […] When the oil gets into your skin, your immune systems sensor cells recognize urushiol as foreign to your body. These sensor cells then call in protector cells to the area, warning them of the invasion. The protector cells defend your body against the intruder by attacking the urushiol in the skin. Unfortunately, some of your bodys normal skin cells are casualties of this war, which is what leads to the itchiness and swelling of a poison ivy rash. […] This rash is a type of allergic contact dermatitis in the same family as the rashes some people get from wearing jewelry or metal belt buckles or from using certain fragrances or cosmetics.

• #42 Everything you need to know about poison ivy | News | Des Moines University

  https://www.dmu.edu/blog/2019/08/everything-you-need-to-know-about-poison-ivy/

  Not everybody has a poison ivy sensitivity, but make no mistake, you can absolutely develop one at any time. Many people have made the claim that they are immune to poison ivy only to find out later, even at ages 50 and 60, that they have developed a horrible reaction to it. […] Fluid from poison ivy blisters does not contain urushiol and cannot cause a rash. The rash doesn’t spread; it just erupts at different times based on the amount of urushiol, the thickness of the skin, and where it spreads when you rub or scratch your skin. […] If you do want to treat it, skip the home remedies for poison ivy and go see your doctor. It’s unlikely that over-the-counter steroid creams are going to have the potency necessary to improve symptoms. […] If the case is bad enough, your doctor might prescribe systemic steroids. It’s important to note that there is no difference in the bioavailability of a shot versus pills; in other words, the pills work just as well as a shot.

• #43 3 Causes of Poison Ivy & How To Treat It | Vujevich Dermatology

  https://www.vucare.com/2019/09/20/causes-of-poison-ivy/

  Poison ivy rash is caused by urushiol oil. Eighty to 90 percent of people exposed to 50 micrograms of urushiol (thats less than one grain of table salt!) develop a rash. But, some people see no reaction from contact with urushiol oil. […] Sensitivity to urushiol oil can change over your lifetime. Children who developed the rash as a child may completely lose their sensitivity to the oil. Likewise, adults who never had the rash as a child may develop a sensitivity to the oil.

• #44 Poison Ivy and the Immune System | HowStuffWorks

  https://science.howstuffworks.com/life/botany/poison-ivy2.htm

  The allergic reaction to poison ivy is known as delayed hypersensitivity. Unlike immediate hypersensitivity, which causes an allergic reaction within minutes of exposure to an antigen, delayed hypersensitivity reactions don’t emerge for several hours or even days after the exposure. […] Most people don’t have a reaction the first time they touch poison ivy, but develop an allergic reaction after repeated exposure. Everyone has a different sensitivity, and therefore a slightly different reaction, to poison ivy. Sensitivity usually decreases with age and with repeat exposures to the plant.

• #45 A poison ivy primer | Smithsonian Institution

  https://www.si.edu/stories/poison-ivy-primer

  In humans, contact with poison ivy causes a reaction known as a cell-mediated immune response. Basically, as Pell explains, the urushiol binds to proteins in the membrane of your skin cells and interferes with their ability to communicate with other cells. It tricks your immune system into regarding your own skin cells as foreign. Urushiol is not an irritant burning your skin, Pell adds. The rash is actually a result of your own immune system attacking your own skin cells. […] Ten to 15 percent of people are immune to poison ivy and will never have a rash. Repeated contact however will not give you immunity, in fact just the opposite, Pell explains. The rashes get worse and worse as your immune system gets better and better at recognizing urushiol.

• #46 Allergic reactions caused by poison ivy | Gouvernement du Québec

  https://www.quebec.ca/en/health/health-issues/a-z/allergic-reactions-caused-by-poison-ivy

  Symptoms may be more severe in people who have had a significant allergic reaction to poison ivy in the past. […] Note that antihistamines (drugs used to treat allergies) do not directly affect allergic reactions to poison ivy. These drugs aim to reduce or eliminate the effects of histamine, but the poison ivy does not cause the release of this substance. […] The urushiol in the sap, which is responsible for allergic reactions, is an oily substance that does not evaporate. It can therefore remain poisonous for several months.

• #47 Urushiol-induced contact dermatitis – Wikipedia

  https://en.wikipedia.org/wiki/Urushiol-induced_contact_dermatitis

  Urushiol-induced contact dermatitis is caused by contact with a plant or any other object containing urushiol oil. The oil adheres to almost anything with which it comes in contact, such as towels, blankets, clothing, and landscaping tools. Clothing or other materials that touch the plant and then, before being washed, touch the skin are common causes of exposure. […] Urushiol is fat-soluble, penetrating the stratum corneum of the skin, then binding to Langerhans cells in the epidermis. The affected cells then migrate to lymph nodes, where T cells become activated, then return to the skin where they stimulate an urushiol-activated dermatitis. The toxic effect is indirect, mediated by an induced immune response. The oxidized urushiols act as haptens, chemically reacting with, binding to, and changing the shape of integral membrane proteins on exposed skin cells.

• #48 Poison Ivy – Skin Disorders – Merck Manual Consumer Version

  https://www.merckmanuals.com/home/skin-disorders/itching-and-dermatitis/poison-ivy

  Poison ivy is an allergic contact dermatitis that causes a very itchy rash caused by exposure to the oil urushiol, which coats the leaves of poison ivy plants. […] About 50 to 70% of people are sensitive to the plant oil urushiol contained in poison ivy, poison oak, and poison sumac. Similar oils are also present in the shells of cashew nuts; the leaves, sap, and fruit skin of the mango; and Japanese lacquer. Once a person has been sensitized by contact with these oils, subsequent exposure causes a rash (allergic contact dermatitis). […] The oils are quickly absorbed into the skin and tightly stick to skin, to clothing, to items such as outdoor tools or equipment, and to pet fur for long periods of time and can still cause the rash. Smoke from burning plants also contains the oil and may cause a reaction in certain people.

• #49 Everything you need to know about poison ivy | News | Des Moines University

  https://www.dmu.edu/blog/2019/08/everything-you-need-to-know-about-poison-ivy/

  Urushiol can transfer from the plant to something that a person then touches. For example, urushiol is oftentimes transferred from pets: Your dog walks through poison ivy, gets urushiol on its fur, you pet the dog, you get poison ivy. […] The amazing thing about urushiol is that it can remain allergenic on clothing for up to 10 years! That’s right you can get urushiol on your jeans, put them in a drawer and pull them out years later and still get a blistering rash from the leftover urushiol. […] A particularly cruel aspect of poison ivy is that the rash can take anywhere from 24 hours to seven days to develop. This leads to the misconception that the rash spreads. The timing with which poison ivy symptoms erupt depends on three things: The amount of urushiol involved, The thickness of the skin involved, The sensitivity of the person exposed.

• #50 Poison Ivy, Oak, and Sumac Rash – Stanford Medicine Children’s Health

  https://www.stanfordchildrens.org/en/topic/default?id=poison-ivy-oak-and-sumac-rash-85-P00306

  Poison ivy, oak, and sumac rash is caused by the body’s reaction to an oil in the plants called urushiol. […] The plants make an oil called urushiol. Urushiol gets on your skin if you touch the plants. […] Urushiol can stay active on any surface for a year or more and still cause skin rash. […] The rash cannot be spread from person to person by touching the blisters, or from the fluid inside the blisters. But oil that remains on skin, clothes, or shoes can be spread to another person and cause a rash.

• #51 Everything you need to know about poison ivy | News | Des Moines University

  https://www.dmu.edu/blog/2019/08/everything-you-need-to-know-about-poison-ivy/

  Urushiol can transfer from the plant to something that a person then touches. For example, urushiol is oftentimes transferred from pets: Your dog walks through poison ivy, gets urushiol on its fur, you pet the dog, you get poison ivy. […] The amazing thing about urushiol is that it can remain allergenic on clothing for up to 10 years! That’s right you can get urushiol on your jeans, put them in a drawer and pull them out years later and still get a blistering rash from the leftover urushiol. […] A particularly cruel aspect of poison ivy is that the rash can take anywhere from 24 hours to seven days to develop. This leads to the misconception that the rash spreads. The timing with which poison ivy symptoms erupt depends on three things: The amount of urushiol involved, The thickness of the skin involved, The sensitivity of the person exposed.

• #52 Poison Ivy – Skin Disorders – Merck Manual Consumer Version

  https://www.merckmanuals.com/home/skin-disorders/itching-and-dermatitis/poison-ivy

  Poison ivy is an allergic contact dermatitis that causes a very itchy rash caused by exposure to the oil urushiol, which coats the leaves of poison ivy plants. […] About 50 to 70% of people are sensitive to the plant oil urushiol contained in poison ivy, poison oak, and poison sumac. Similar oils are also present in the shells of cashew nuts; the leaves, sap, and fruit skin of the mango; and Japanese lacquer. Once a person has been sensitized by contact with these oils, subsequent exposure causes a rash (allergic contact dermatitis). […] The oils are quickly absorbed into the skin and tightly stick to skin, to clothing, to items such as outdoor tools or equipment, and to pet fur for long periods of time and can still cause the rash. Smoke from burning plants also contains the oil and may cause a reaction in certain people.

• #53 Poison ivy, oak, and sumac: When does the rash appear?

  https://www.aad.org/public/everyday-care/itchy-skin/poison-ivy/rash-appear

  Every part of these plants the leaves, stem, vines, flowers, and roots contains an oil called urushiol (yur-oo-shee-aal). When this oil touches your skin, it can cause an allergic reaction. Anyone who develops an allergic reaction gets a rash. […] When you use a lawnmower or trimmer to get rid of these plants, you break the plants into thousands of tiny pieces, which become airborne. If several tiny pieces land on you or someone else, many rashes can develop. This can cause a serious allergic reaction. […] When you burn these plants, their toxic oil gets into the air. The airborne particles can: Land on anyones skin, including yours, and lead to a rash. Cause a serious (or life-threatening) reaction when you and anyone else in the area breathes in the toxic smoke.

• #54 Poison Ivy Rash, Poison Oak, Poison Sumac: Symptoms, Causes & Treatment

  https://my.clevelandclinic.org/health/diseases/10655-poison-plants-poison-ivy–poison-oak–poison-sumac

  Some situations increase your risk of problems if youre exposed to poison ivy, poison oak or poison sumac. […] When poisonous plants burn, they release urushiol into the air. You may develop a rash on your face from coming into contact with the smoke or on the lining of your nasal passages, mouth and throat from inhaling the smoke. […] Poison ivy rashes cause mild (but annoying) symptoms that go away within a week or two. Rarely, a skin rash can last for longer than a month. […] Poison oak and poison sumac rashes should go away within one to two weeks.

• #55 Poison Ivy Rash: Pictures, Symptoms, and Treatment

  https://www.healthline.com/health/outdoor-health/poison-ivy-pictures-remedies

  If you come into contact with poison ivy that is burning, you may inhale plant compounds. This can lead to irritation in the lungs, airways, and eyes. […] A poison ivy rash will only develop on skin that comes into contact with the plants oils. However, you can transfer the oil to other parts of your body if urushiol remains on your hands.

• #56 Poison Ivy Rash, Poison Oak, Poison Sumac: Symptoms, Causes & Treatment

  https://my.clevelandclinic.org/health/diseases/10655-poison-plants-poison-ivy–poison-oak–poison-sumac

  A poison ivy rash on your skin usually looks like red, itchy bumps. […] Poison oak rash and poison sumac rash look the same as poison ivy rash. This is because urushiol oil causes the same allergic reaction no matter which poisonous plant you touch. […] No matter how long it takes for a rash to appear, it usually comes in stages and peaks within one to 14 days of exposure. However, symptoms can develop as long as 21 days after initial exposure to urushiol oil for those whove never been in contact with it before. […] It may look like your rash is spreading, but youre actually developing new rashes on areas of skin that came into contact with urushiol oil. […] You cant get a poison ivy rash by touching another persons rash. But you could develop a rash if you touch the oil on another persons body or clothes.

• #57 Poison ivy, oak, and sumac: What does the rash look like?

  https://www.aad.org/public/everyday-care/itchy-skin/poison-ivy/what-rash-looks-like

  While it may look like the rash is spreading, what’s most likely happening is that you’re developing one or more new rashes. This happens because you either got urushiol (the oil from these plants that causes the rash) on more than one area of your skin. […] If your new rash appears near the current rash, it can look like the rash is spreading. […] Many people also mistakenly believe that when they touch their rash, they can spread the rash from one part of their body to another. You cannot spread the rash. […] How long you have a rash depends on whether you’ve had a rash from one of these plants before. Here’s the general rule: Previous rash from poison ivy, oak, or sumac: The rash tends to last 1 to 14 days before it clears on its own. […] Never had a rash from poison ivy, oak, or sumac: You can have a rash for 21 days or longer before it goes away.

• #58 Everything you need to know about poison ivy | News | Des Moines University

  https://www.dmu.edu/blog/2019/08/everything-you-need-to-know-about-poison-ivy/

  Urushiol can transfer from the plant to something that a person then touches. For example, urushiol is oftentimes transferred from pets: Your dog walks through poison ivy, gets urushiol on its fur, you pet the dog, you get poison ivy. […] The amazing thing about urushiol is that it can remain allergenic on clothing for up to 10 years! That’s right you can get urushiol on your jeans, put them in a drawer and pull them out years later and still get a blistering rash from the leftover urushiol. […] A particularly cruel aspect of poison ivy is that the rash can take anywhere from 24 hours to seven days to develop. This leads to the misconception that the rash spreads. The timing with which poison ivy symptoms erupt depends on three things: The amount of urushiol involved, The thickness of the skin involved, The sensitivity of the person exposed.

• #59 Outsmarting Poison Ivy and Other Poisonous Plants | FDA

  https://www.fda.gov/consumers/consumer-updates/outsmarting-poison-ivy-and-other-poisonous-plants

  First comes the itching, then a red rash, and then blisters. These symptoms of poison ivy, poison oak, and poison sumac can emerge any time from a few hours to several days after exposure to the plant oil found in the sap of these poisonous plants. The culprit: the urushiol oil. […] The rash will occur only where the plant oil has touched the skin, so a person with poison ivy cant spread it on the body by scratching. It may seem like the rash is spreading if it appears over time instead of all at once. But this is either because the plant oil is absorbed at different rates on different parts of the body or because of repeated exposure to contaminated objects or plant oil trapped under the fingernails. Even if blisters break, the fluid in the blisters is not plant oil and cannot further spread the rash.

• #60 Outsmarting Poison Ivy and Other Poisonous Plants | FDA

  https://www.fda.gov/consumers/consumer-updates/outsmarting-poison-ivy-and-other-poisonous-plants

  First comes the itching, then a red rash, and then blisters. These symptoms of poison ivy, poison oak, and poison sumac can emerge any time from a few hours to several days after exposure to the plant oil found in the sap of these poisonous plants. The culprit: the urushiol oil. […] The rash will occur only where the plant oil has touched the skin, so a person with poison ivy cant spread it on the body by scratching. It may seem like the rash is spreading if it appears over time instead of all at once. But this is either because the plant oil is absorbed at different rates on different parts of the body or because of repeated exposure to contaminated objects or plant oil trapped under the fingernails. Even if blisters break, the fluid in the blisters is not plant oil and cannot further spread the rash.

• #61 Poison ivy – oak – sumac rash Information | Mount Sinai – New York

  https://www.mountsinai.org/health-library/injury/poison-ivy-oak-sumac-rash

  The rash is caused by skin contact with the oils (resin) of certain plants. The oils most often enter the skin rapidly. […] The reaction can vary from mild to severe. In rare cases, the person with the rash needs to be treated in the hospital. The worst symptoms are often seen during days 4 to 7 after coming in contact with the plant. The rash may last for 1 to 3 weeks.

• #62 Poison Ivy, Oak, and Sumac Rash

  https://www.massgeneral.org/condition/poison-ivy-poison-oak

  Poison ivy, poison oak, and poison sumac are types of American plants. They each grow in different parts of the country. The plants cause allergic contact dermatitis in most people who touch them. The rash is caused by the bodys reaction to an oil in the plants called urushiol. […] The plants make an oil called urushiol. This oil gets on your skin if you touch the plants. And its easily spread from the plants to other objects. These include garden tools, clothing, toys, and pet fur. You can also inhale it from smoke if the plants are burned. Urushiol can stay active on any surface for a year or more and still cause skin rash. The rash doesnt show up right away. But you can spread the oils around your body without knowing it. […] Poison ivy, oak, and sumac rash is not contagious. It cant be spread from person to person by touching the blisters, or from the fluid inside the blisters. But oil that remains on skin, clothes, or shoes can be spread to another person and cause a rash. […] The rash is caused by a reaction to an oil in the plants called urushiol. […] Treatment is done to reduce itching. Itching can be treated with lotion, cream, or medicine by mouth. […] In some cases, you may need urgent treatment if you have a severe reaction and swelling.

• #63 Having a Poison Ivy Reaction | DCSI Florida DermatologyHaving a Poison Ivy Reaction | DCSI Florida Dermatology

  https://www.mydcsi.com/conditions/skin/inflammatory-skin/poison-ivy-reaction/

  Poison ivy causes an allergic reaction in most people. An allergic reaction to poison ivy is a type of contact dermatitis caused by exposure to urushiol, the oily resin in the plant’s leaves, stems, and roots. When urushiol touches the skin, it binds to skin cells and triggers an immune response in the body, leading to a reaction that manifests as an itchy, red rash with blisters. […] The severity of the reaction can vary depending on the individual’s sensitivity to urushiol, but it is generally considered an allergic contact dermatitis. The reaction typically starts within 12 to 48 hours after exposure and can last from a few days to several weeks. […] A systemic poison ivy reaction occurs when the urushiol oil from poison ivy is absorbed into the bloodstream, causing an allergic reaction throughout the body rather than just at the site of contact. This type of reaction can cause widespread rashes, swelling, and other symptoms beyond the area of exposure. In severe cases, it can lead to symptoms such as difficulty breathing, fever, and swelling of the face or throat, which require immediate medical attention. Systemic reactions are rare but can occur, especially if large amounts of urushiol are involved or if the individual is highly sensitive to it.

• #64 Having a Poison Ivy Reaction | DCSI Florida DermatologyHaving a Poison Ivy Reaction | DCSI Florida Dermatology

  https://www.mydcsi.com/conditions/skin/inflammatory-skin/poison-ivy-reaction/

  Poison ivy causes an allergic reaction in most people. An allergic reaction to poison ivy is a type of contact dermatitis caused by exposure to urushiol, the oily resin in the plant’s leaves, stems, and roots. When urushiol touches the skin, it binds to skin cells and triggers an immune response in the body, leading to a reaction that manifests as an itchy, red rash with blisters. […] The severity of the reaction can vary depending on the individual’s sensitivity to urushiol, but it is generally considered an allergic contact dermatitis. The reaction typically starts within 12 to 48 hours after exposure and can last from a few days to several weeks. […] A systemic poison ivy reaction occurs when the urushiol oil from poison ivy is absorbed into the bloodstream, causing an allergic reaction throughout the body rather than just at the site of contact. This type of reaction can cause widespread rashes, swelling, and other symptoms beyond the area of exposure. In severe cases, it can lead to symptoms such as difficulty breathing, fever, and swelling of the face or throat, which require immediate medical attention. Systemic reactions are rare but can occur, especially if large amounts of urushiol are involved or if the individual is highly sensitive to it.

• #65 Having a Poison Ivy Reaction | DCSI Florida DermatologyHaving a Poison Ivy Reaction | DCSI Florida Dermatology

  https://www.mydcsi.com/conditions/skin/inflammatory-skin/poison-ivy-reaction/

  Poison ivy causes an allergic reaction in most people. An allergic reaction to poison ivy is a type of contact dermatitis caused by exposure to urushiol, the oily resin in the plant’s leaves, stems, and roots. When urushiol touches the skin, it binds to skin cells and triggers an immune response in the body, leading to a reaction that manifests as an itchy, red rash with blisters. […] The severity of the reaction can vary depending on the individual’s sensitivity to urushiol, but it is generally considered an allergic contact dermatitis. The reaction typically starts within 12 to 48 hours after exposure and can last from a few days to several weeks. […] A systemic poison ivy reaction occurs when the urushiol oil from poison ivy is absorbed into the bloodstream, causing an allergic reaction throughout the body rather than just at the site of contact. This type of reaction can cause widespread rashes, swelling, and other symptoms beyond the area of exposure. In severe cases, it can lead to symptoms such as difficulty breathing, fever, and swelling of the face or throat, which require immediate medical attention. Systemic reactions are rare but can occur, especially if large amounts of urushiol are involved or if the individual is highly sensitive to it.

• #66 Poison Ivy Rash: Pictures, Symptoms, and Treatment

  https://www.healthline.com/health/outdoor-health/poison-ivy-pictures-remedies

  Poison ivy rash is caused by contact with poison ivy, a plant that grows almost everywhere in the United States. The sap of the poison ivy plant, also known as Toxicodendron radicans, contains an oil called urushiol. This is the irritant that causes an allergic reaction and rash. […] The allergic reaction caused by poison ivy is known as contact dermatitis. It happens when your skin comes into contact with an irritant, such as urushiol. […] The rash may begin appearing within 12 hours; it can take a few days to fully develop. Its severity depends on how much urushiol you get on your skin. […] A severe poison ivy allergy causes severe swelling, difficulty breathing, and blisters that become inflamed and infected. […] A bacterial infection is a common complication of a poison ivy rash. Repeated scratching can cause microscopic breaks in the skin. Bacteria can make their way into the breaks, and an infection can develop.

• #67 Content – Health Encyclopedia – University of Rochester Medical Center

  https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=90&contentid=p01917

  Poison ivy rash is an itchy, allergic reaction to poison ivy. […] This means the body’s immune system releases certain chemicals that cause a skin reaction. […] Poison ivy has an oil called urushiol. This oil causes the allergic skin reaction. […] The rash may become infected from bacteria. This is often spread from under the fingernails while scratching. […] Poison ivy, oak, and sumac cause an allergic skin reaction. The reaction is caused by oil from the plant. […] The fluid from the blisters doesnt make poison ivy spread. But oil on the skin can cause a rash if wiped on another person.

• #68 Thinking Big about Poison Ivy – Rhody Today

  https://www.uri.edu/news/2013/08/thinking-big-about-poison-ivy/

  Poison Ivy, Sumac and Oak are the most common cause of allergic reaction in the United States. These are plants in the Toxicodendron genus. […] The symptoms are caused by a chemical, urushiol, present in the sap. This is easily contacted from damaged or broken plants, even from dead or decaying plant material or from surfaces that have contacted the chemical, such as clothing, tools and pets. It is also easily contacted from the smoke of burning Poison Ivy plants. This allergy producing chemical can remain active on plant material and surfaces for years. […] The rash can occur from a few hours after exposure up to many days later depending on previous exposures and reactions. Symptoms can continue to develop/persist for up to 21 days. […] The vesicles (blisters) of Poison Ivy dermatitis can become infected and require treatment with antibiotics. Inhaled smoke from burning plants can cause lung irritation and severe respiratory symptoms. Rarely, the immune reaction to urushiol can cause kidney damage.

• #69 Poison Ivy Rash, Poison Oak, Poison Sumac: Symptoms, Causes & Treatment

  https://my.clevelandclinic.org/health/diseases/10655-poison-plants-poison-ivy–poison-oak–poison-sumac

  A poison ivy rash on your skin usually looks like red, itchy bumps. […] Poison oak rash and poison sumac rash look the same as poison ivy rash. This is because urushiol oil causes the same allergic reaction no matter which poisonous plant you touch. […] No matter how long it takes for a rash to appear, it usually comes in stages and peaks within one to 14 days of exposure. However, symptoms can develop as long as 21 days after initial exposure to urushiol oil for those whove never been in contact with it before. […] It may look like your rash is spreading, but youre actually developing new rashes on areas of skin that came into contact with urushiol oil. […] You cant get a poison ivy rash by touching another persons rash. But you could develop a rash if you touch the oil on another persons body or clothes.

• #70 Everything you need to know about poison ivy | News | Des Moines University

  https://www.dmu.edu/blog/2019/08/everything-you-need-to-know-about-poison-ivy/

  First and foremost, you need to know that the stuff that makes a poison ivy plant so miserable is called urushiol. This is the oil that elicits the scratchy rash that those of us who’ve come to know and hate the Devil Plant remember so well. Urushiol is present in the toxicodendron family of plants and is found on the leaves, in the stems, the roots and even the berries of the plants. Poison ivy (Toxicodendron radicans and toxicodendron rydbergii), poison oak (Toxicodendron diversilobum and toxicodendron pubescens), and poison sumac (toxicodendron vernix) plants all produce urushiol; you won’t be able to differentiate the specific plant you brushed up against by the rash it produces. But here’s the thing it doesn’t really matter. Each of these three plants all make urushiol, and it’s the urushiol that makes you miserable.

• #71 Poison Ivy Rash, Poison Oak, Poison Sumac: Symptoms, Causes & Treatment

  https://my.clevelandclinic.org/health/diseases/10655-poison-plants-poison-ivy–poison-oak–poison-sumac

  A poison ivy rash on your skin usually looks like red, itchy bumps. […] Poison oak rash and poison sumac rash look the same as poison ivy rash. This is because urushiol oil causes the same allergic reaction no matter which poisonous plant you touch. […] No matter how long it takes for a rash to appear, it usually comes in stages and peaks within one to 14 days of exposure. However, symptoms can develop as long as 21 days after initial exposure to urushiol oil for those whove never been in contact with it before. […] It may look like your rash is spreading, but youre actually developing new rashes on areas of skin that came into contact with urushiol oil. […] You cant get a poison ivy rash by touching another persons rash. But you could develop a rash if you touch the oil on another persons body or clothes.

• #72 Poison Ivy – Skin Disorders – Merck Manual Consumer Version

  https://www.merckmanuals.com/home/skin-disorders/itching-and-dermatitis/poison-ivy

  Poison ivy is an allergic contact dermatitis that causes a very itchy rash caused by exposure to the oil urushiol, which coats the leaves of poison ivy plants. […] About 50 to 70% of people are sensitive to the plant oil urushiol contained in poison ivy, poison oak, and poison sumac. Similar oils are also present in the shells of cashew nuts; the leaves, sap, and fruit skin of the mango; and Japanese lacquer. Once a person has been sensitized by contact with these oils, subsequent exposure causes a rash (allergic contact dermatitis). […] The oils are quickly absorbed into the skin and tightly stick to skin, to clothing, to items such as outdoor tools or equipment, and to pet fur for long periods of time and can still cause the rash. Smoke from burning plants also contains the oil and may cause a reaction in certain people.

• #73 From leaf to itch — Harvard Gazette

  https://news.harvard.edu/gazette/story/2016/09/from-leaf-to-itch/

  Researchers from Harvard Medical School and Boston Childrens Hospital are among the first to trace poison ivys molecular path, following the effect from leaf to burning itch and pointing a potentially soothing way forward. […] Investigators led by Assistant Professor of Microbiology and Immunobiology Florian Winau were able to do what previous teams hadnt managed: illuminate the role of a key molecule called CD1a in a chain reaction that begins when the shiny leaf touches the skin. […] The findings, published last month in Nature Immunology, took advantage of mice engineered to produce the molecule by colleagues at Kyoto University, which enabled observation of the entire inflammatory pathway for the first time. […] When urushiol comes into contact with Langerhans cells in the skin, the Langerhans cells load urushiol on CD1a molecules that activate the immune systems T cells. The T cells produce interleukin 17 and interleukin 22, which cause inflammation and itchiness. […] Researchers eased the rash experimentally by using an antibody that interfered with communication between the CD1a molecule and T cells.

• #74 From leaf to itch — Harvard Gazette

  https://news.harvard.edu/gazette/story/2016/09/from-leaf-to-itch/

  Researchers from Harvard Medical School and Boston Childrens Hospital are among the first to trace poison ivys molecular path, following the effect from leaf to burning itch and pointing a potentially soothing way forward. […] Investigators led by Assistant Professor of Microbiology and Immunobiology Florian Winau were able to do what previous teams hadnt managed: illuminate the role of a key molecule called CD1a in a chain reaction that begins when the shiny leaf touches the skin. […] The findings, published last month in Nature Immunology, took advantage of mice engineered to produce the molecule by colleagues at Kyoto University, which enabled observation of the entire inflammatory pathway for the first time. […] When urushiol comes into contact with Langerhans cells in the skin, the Langerhans cells load urushiol on CD1a molecules that activate the immune systems T cells. The T cells produce interleukin 17 and interleukin 22, which cause inflammation and itchiness. […] Researchers eased the rash experimentally by using an antibody that interfered with communication between the CD1a molecule and T cells.

• #75 From leaf to itch — Harvard Gazette

  https://news.harvard.edu/gazette/story/2016/09/from-leaf-to-itch/

  Researchers from Harvard Medical School and Boston Childrens Hospital are among the first to trace poison ivys molecular path, following the effect from leaf to burning itch and pointing a potentially soothing way forward. […] Investigators led by Assistant Professor of Microbiology and Immunobiology Florian Winau were able to do what previous teams hadnt managed: illuminate the role of a key molecule called CD1a in a chain reaction that begins when the shiny leaf touches the skin. […] The findings, published last month in Nature Immunology, took advantage of mice engineered to produce the molecule by colleagues at Kyoto University, which enabled observation of the entire inflammatory pathway for the first time. […] When urushiol comes into contact with Langerhans cells in the skin, the Langerhans cells load urushiol on CD1a molecules that activate the immune systems T cells. The T cells produce interleukin 17 and interleukin 22, which cause inflammation and itchiness. […] Researchers eased the rash experimentally by using an antibody that interfered with communication between the CD1a molecule and T cells.

• #76 Urushiol – Wikipedia

  https://en.wikipedia.org/wiki/Urushiol

  In most individuals, urushiol causes an allergic skin rash on contact, known as urushiol-induced contact dermatitis. […] To cause an allergic dermatitis reaction, the urushiol is first oxidized to create two double-bonded oxygens on the chemical. It then reacts with a protein nucleophile to trigger a reaction within the skin. Dermatitis is mediated by an acquired immune response. Urushiol is too small to directly activate an immune response. Instead, it attaches to certain proteins of the skin, where it acts as a hapten, leading to a type IV hypersensitivity reaction. […] After being absorbed by the skin, it is recognized by the immune system’s dendritic cells, otherwise called Langerhans cells. These cells then migrate to the lymph nodes, where they present the urushiol to T-lymphocytes and thus recruit them to the skin, and the T-lymphocytes cause pathology through the production of cytokines and cytotoxic damage to the skin. This causes the painful rash, blisters, and itching.

• #77 Poison Ivy, Oak, and Sumac Allergies: Symptoms, Diagnosis, Treatment

  https://www.webmd.com/allergies/poison-ivy-oak-sumac

  Poison ivy, poison oak, and poison sumac are three of the most common causes of allergic contact dermatitis in North America. Some experts estimate that three out of four people are sensitive to the chemical found in these plants, although the degree of sensitivity varies. Some people are very sensitive and will have a quick reaction upon contact with a small amount of urushiol. For those who are less sensitive, exposure to a large amount of urushiol is necessary before a reaction develops. […] An allergy to a poison plant is diagnosed based on the typical pattern of symptoms and the appearance of the rash. […] An allergic reaction to a poison plant cannot be cured, but the symptoms can be treated. You may take cool showers and apply an over-the-counter lotion — such as calamine lotion — to help relieve the itch. If your reaction is more severe or involves mucus membranes (membranes found in the eyes, nose, mouth, and genitals), you may need a prescription drug, such as prednisone, to help control the reaction. Topical steroid prescription ointments are very helpful for the itch and inflammation. […] Most rashes caused by poison ivy, poison oak, or poison sumac are mild and last from five to 12 days. In severe cases, the rash can last for 30 days or longer.

• #78 Poison Ivy – Skin Disorders – Merck Manual Consumer Version

  https://www.merckmanuals.com/home/skin-disorders/itching-and-dermatitis/poison-ivy

  Doctors base the diagnosis of poison ivy dermatitis on the characteristic rash and on the person’s exposure to urushiol oil. […] The most effective treatment is with corticosteroids. Small areas of rash are treated with strong corticosteroids applied to the skin, such as triamcinolone, clobetasol, or diflorasone. However, if the face and genitals are affected, strong corticosteroids should not be used or should be used only for short periods of time because they can otherwise damage this delicate skin. People with large areas of rash or significant facial swelling are given corticosteroids taken by mouth. […] Recognizing and avoiding the plants is the best prevention. Poison ivy plants (Toxicodendron radicans) grow throughout the United States except Alaska, Hawaii, and parts of the West Coast, as well as in Eastern Canada, Mexico, Central America, Bermuda and the Bahamas.

• #79 Toxicodendron Contact Dermatitis: A Case Report and Brief Review

  https://pmc.ncbi.nlm.nih.gov/articles/PMC7733371/

  The combination of itching, the linear configuration of the lesions, and a history of recent exposure to the plant is essentially pathognomic. […] The rash and related symptoms can last a month or more, with or without treatment. […] Key to preventing TCD is the ability to recognize these plants and, thus, avoid contact with them. […] Once the immune system is triggered by the penetration of the oily resin, however, no amount of washing can help. […] While there is no entirely satisfactory treatment for TCD other than the tincture of time, longer-course glucocorticoid therapy, such as triamcinolone or prednisone, has been shown to be effective in relieving symptoms associated with TCD. […] The risks and benefits of all treatments, along with the understanding that the problem will eventually resolve on its own, with or without treatment, should always be discussed with each patient to assist the individual in making an informed decision regarding the treatment plan.

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