Dermatitis Associated with Poison Ivy

How the Skin Rash (Dermatitis) starts?

A poison ivy rash is a form of contact dermatitis caused by an allergic reaction to the resins (oily sap) of the poison ivy, oak, or sumac plant. It will usually begin to appear 1 to 2 days after coming in contact with urushiol (say: oo-roo-shee-ohl). The affected area will get red and swollen. A day or so later, small blisters will begin to form, and the rash will become very itchy. Avoid scratching the blisters during this time. Bacteria from under your fingernails can get into the blisters and cause an infection. After about a week, the blisters will start to dry up and the rash will start to go away. In severe cases, where the poison ivy rash covers large parts of the body, it may last much longer.

What does Poison Ivy look like?Â

Poison Ivy Poison ivy is the most common and widespread plant of the three. It is characterized by its leaves, which have three or five serrated-edge, pointed leaflets. Its leaves assume bright colors in the fall, turning yellow and then red. Poison ivy grows as a vine or free-standing plant in the East, Midwest, and South and as a shrub in the far northern and western United States, including the Great Lakes and Canada.

 What does Poison Oak plant look like?

Poison Oak Poison Oak has three oak-like leaves and grows as a low shrub in the East and as both low and high shrubs in the West, where it is most prevalent. Poison oak produces whitish flowers from August to November that dry and can remain for many months. In the fall, the leaves assume bright colors, turning yellow and then red.Â

What does Poison Sumac plant look like?

Poison Sumac Poison sumac has seven to 13 staggered leaflets with one on the tip of the plant and grows as a shrub or small tree. It is found mainly in the eastern United States, growing in peat bogs and swamps. Poison sumac is distinguished from nonpoisonous sumac by the location of its fruit, which grows between the leaf and the branch as opposed to the ends of the branches. Â

How does poison ivy cause a rash?

The poison ivy plant contains an oil called urushiol (say: oo-roo-shee-ohl). Most people are allergic to urushiol. If you are allergic to it and you get it on your skin, you’ll develop an itchy, red rash. You can get the oil on your skin by:

  • touching the poison ivy plant
  • touching any clothing, including shoes, that have come in contact with the plant.
  • touching any gardening tools that may have the oil on it.
  • touching any outdoor pets that have been around poison ivy and have gotten the oil on their hair.
  • burning the poison ivy plant. The oil from the plant is carried in the smoke.

How it is Treated?

  • The skin should be washed thoroughly with soap and cool water as soon as possible following exposure. Because the resin enters skin quickly, it must be washed off completely within 30 minutes to prevent a reaction. Scrub under the fingernails with a brush to prevent spreading of the resin to other parts of the body by touching or scratching. (Use cool water to wash skin. Warm water opens pores and may allow urushiol to penetrate deeper into the skin causing a more severe reaction.)
  • Calamine Lotion and topical hydrocortisone cream may be applied to the skin to help decrease itching and blistering.
  • Zanfel Wash For Poison Ivy, Oak & Sumac (Urushiol), available over-the-counter can lessen the severity of the rash following exposure to poison ivy.
  • Antihistamines, such as Benadryl (diphenhydramine) help relieve itching and can be mildly sedating. Bathing in tepid water with Aveeno Soothing Bath Treatment may also soothe itchy skin. Aluminum acetate (Domeboro solution) soaks can also be helpful to dry the rash and reduce itch.
  • Ivy Block is a barrier cream, available over-the-counter, that can reduce skin exposure to poison ivy.
  • Some people have severe allergic reactions to these plants and can have swelling in the throat, breathing problems, weakness, dizziness and bluish lips. If any of these reactions occur, seek emergency medical care.

How to protect oneself from Poison Ivy?

  • Learn to identify poison ivy, oak, and sumac to avoid exposure.
  • Cover skin with clothing (long sleeves, long pants, shoes, and socks) when walking in the woods or in areas where these plants may grow.
  • Use barrier cream such as Ivy Block or Stokoguard when working in areas where poison ivy is present.
  • Be aware of resins carried by pets.
  • Wash exposed skin thoroughly with soap and cool water as soon as possible following exposure.
  • Also, keep your hands away from your eyes, mouth and face.
  • Wash the clothing and shoes of the exposed person with soap and hot water. Resin can linger on these surfaces for days.
  • May and June are the best times to apply control measures to these poison plants, but it can be done any time of the year.
  • Burning can be dangerous and is not recommended for disposal or as a control measure because the toxic oil from the plant can be carried in smoke.
  • Spraying the foliage with glyphosate (sold under the trade names of Roundup or Kleenup and others) is recommended.
  • Remember that the vine left on the tree or fence still has oil in it so be careful if you pull the vine down. Even if the vine is brown and looks dead, it still may have oil in it.

Myths versus Facts

Myth: Scratching poison ivy blisters will spread the rash.
Fact: The fluid in the blisters willl not spread the rash. Before blisters form, the rash can only be spread by unbound urushiol. Avoid scratching of blisters. Fingernails may carry bacteria that could cause an infection.

Myth: Poison ivy rash is “contagious.”
Fact: The rash is a reaction to urushiol. The rash cannot pass from person to person after the urushiol binds.

Myth: After the first time, I can’t get poison ivy again.
Fact: Although not everyone reacts to poison ivy upon first or subsequent exposures, people generally become more sensitized with each contact and may react more severely to subsequent exposures. In addition, the reaction may last longer.

Myth: Once allergic, always allergic to poison ivy.
Fact: A person’s sensitivity changes over time, even from season to season. People who were sensitive to poison ivy as children may not be allergic as adults.

Myth: Dead poison ivy plants are no longer toxic.
Fact: Urushiol remains active for up to five years. Never handle dead plants that look like poison ivy without proper protection.


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