Facts & Fiction About Poison Oak and Ivy

Poison Oak and Ivy Facts

Poison Oak (Rhus diversiloba), poison ivy (Rhus toxicodendron L.), and poison sumac (Rhus toxicodendron V.) emit the poisonous, oily irritant urushiol (pronounced oo-roo-she-all) on the plant's stem, roots, branches, and leaves. The urushiol chemically "locks on" to skin proteins within 20 minutes after exposure to the plants (including dormant plants or long-dead prunings), contaminated clothes or tools, or even contaminated pets.

Contact with this annoying oil produces a rash in three out of four people. The rash can begin within a few hours after contact, or it can start three to five days later. The rash starts with itchiness and swelling, followed by a reddish inflammation of tiny pimples. Blisters then form and couple in a chain-like reaction. A clear fluid oozes from the blisters. This fluid then hardens to a yellowish crust. Left untreated, the rash (a typical histamine response) will last three to five weeks.

Poison oak, ivy, sumac and other members for the Rhus family grow in all portions of the North American continent (except Nevada, Alaska, and Hawaii) at elevations below 4,000 feet with a rainfall above 8 inches per year. These plants are a significant cause of workers' compensation claims in the United States. They are also the source of considerable distress to outdoor recreationalists and hobbyists.

Questions and Answers

  1. WHAT CAN I DO TO RELIEVE THE RASH?

    There is no cure for the rash once it begins, only relief of the symptoms. Avoid further contact with the plant oil if possible.

    Minor itching, pain, oozing, and swelling can be relieved with over-the-counter anti-itch treatments that contain zinc acetate, zinc oxide, or hydrocortisone. In severe cases a practitioner can prescribe antihistamine creams, tablets, or shots.

  2. DO THE BLISTERS CAUSE THE RASH TO SPREAD?

    No. The blisters are the body's natural allergic reaction to poisonous plants. If the blisters break and ooze, the fluid does not contain the oil that cause spreading. Oil from the original contact with the plant will continue spreading for the first 1 or 2 days. If new areas of rash appear after 3 days, you are getting re-exposed to the plant oil, most likely from contaminated clothing, tools, or even your pets.

  3. HOW LONG WILL THE RASH LAST?

    Mild cases can last 5 to 12 days. More severe cases can last up to 30 days or longer.

  4. CAN I GET THE RASH FROM SOMEONE ELSE?

    Generally speaking, no. Once the rash appears (i.e. within 1-3 days), the original oil has all bonded to the victim's skin, so it can't be spread to others.

  5. HOW LONG DOES THE URUSHIOL OIL LAST?

    The oil does not evaporate and can remain active for a year or longer after being picked up on tools, clothing, animal fur, etc.

  6. SHOULD I BREAK THE BLISTERS?

    Never break the blisters! An open blister can easily become infected and lead to blood poisoning. If the blisters break, cover loosely with a sterile bandage. In severe cases, contact your practitioner.

  7. I'VE NEVER GOTTEN THE RASH BEFORE. CAN I GET IT NOW?

    Yes, you can begin getting the rash at any time during your life. Three out of four people are sensitive to poison oak and ivy. Sensitivity is just a matter of being exposed enough times until the body becomes allergic to the poison oil.

  8. SHOULD I WRAP OR COVER THE RASH WITH BANDAGES?

    Air is helpful to healing any wound. If you cover the rash with a sterile bandage, cover loosely to allow healing oxygen to reach the surface of the skin. It is important to keep the rash very clean; changing the sterile bandage frequently reduces the risk of infection. Seek medical attention if rash becomes red, feverish, or shows other signs of infection.

  9. ARE DEAD PLANTS SAFE TO TOUCH?

    No. The poison oil remains toxic and does not evaporate. All parts of the living or dead poison plants, including the roots, contain the urushiol oil. Be especially careful of dead vines on firewood and leafless vines in the winter.

  10. DO I NEED TO CLEAN URUSHIOL OIL FROM CLOTHING AND TOOLS?

    Yes. The poison oil will remain active on these articles and can cause a rash months, or even years, later. Removal of the oil with a thorough cleansing is important to avoid contaminating unsuspecting victims in the future.

  11. CAN I GET THE RASH FROM MY PETS?

    Yes. Since the animals' fur protects their skin from the poison oil, they won't get a rash. However, the oil will remain on their fur and will contaminate you when you touch them. Removal of the poison oil from your pet with an effective cleanser will help avoid contaminating you and your family with an unwanted and unexpected rash.

  12. IS IT POSSIBLE TO GET A RASH BY BREATHING THE SMOKE OF BURNING POISON PLANTS?

    Yes. Urushiol is carried in the smoke from burning leaves or brush. If you think you have inhaled the oil, see your practitioner immediately; this can be a very serious condition. In several states it is illegal to burn poison plants. NEVER BURN THEM! Avoid breathing the smoke.

  13. DOES BLEACH REMOVE THE URUSHIOL OIL OR HELP HEAL THE RASH?

    No. Bleach may appear to be a quick fix to poison plant rash. However, bleach removes the top layer(s) of your skin. Using it can irritate your skin and in the process weaken it so that the rash may become worse, or it could lead to an infection. Your skin may then become more sensitive to getting the rash in the future.

References

  1. The majority of this handout was provided by Tec Laboratories, Inc. Albany, Oregon 97321, 1-800-ITCHING, www.teclabsinc.com. Makers of Tecnu, Outdoor Skin Cleanser; CalaGel, Medicated Anti-itch Gel; and CortiCool, 1.0% Hydrocortisone Anti-itch Gel.