The poisonous sap produced by poison oak and ivy is called urushiol ("oo roo she all"). It penetrates the skin and bonds to proteins in cell membranes in 10-15 minutes. It does not dissolve in water, is difficult to wash off and can remain toxic for a long time. Unwashed clothes may retain their toxicity for over a year. The good news is that urushiol is located inside the plant, so mere contact with the plant is unlikely to result in a skin reaction. The bad news is that damage to any part of the fragile plant releases the toxin. Wind and chewing insects cause enough damage to release the toxin. If you ride against or fall into a patch of poison oak or ivy, you damage the plant and are exposed. Up to 85% of the population is allergic to urushiol. You can be exposed to the sap from direct contact with the plant or with urushiol on clothing, gear or your bicycle. The blistering, oozing rash is caused by the body's T-cells destroying the urushiol molecule and surrounding cell material.
If you find yourself exposed or come across a rider who is exposed, act quickly (remember, the oil bonds in 10-15 minutes). Washing after 15 minutes will probably not prevent the outbreak but may prevent further contamination of other areas. Once the urushiol is removed from the skin, you cannot transmit the toxin to other people, i.e. the rash is not contagious. Even the liquid in the blisters will not transmit the rash.
First Aid for the Field
- Wash the contact areas with lots of cool water.
- Wipe the skin with rubbing (isopropyl) alcohol, available at any pharmacy or supermarket, then rinse with cool water. Alcohol prep pads are inexpensive, more easily carried than liquid alcohol and may work as well.
- Alcohol removes the skin's protective barrier - don't further expose yourself because the urushiol will penetrate faster.
- Tecnu and Zanfel are reported to be effective products to decontaminate skin. Don't forget to clean gear and equipment without re-contaminating yourself.
When to Worry
See a doctor immediately if you or a rider:
- Shows immediate swelling or has trouble breathing (anaphylaxis).
- Has a history of severe reactions.
- Has severe, uncontrollable itching.
- Has a rash on the face or genitals or on more than 30% of the body.
- Is exposed to the smoke of burning poison oak or ivy.
Things Not to Do
- Do not burn poison oak or ivy leaves. The smoke is toxic.
- Don't put your fingers in your eyes, ears, nose, or mouth. Don't eat, and don't touch your genitals (bathroom breaks) until your hands are decontaminated.
- Don't wash the skin with bleach - its vapors are irritating and it inflames the skin.
- Don't use products with jewelweed, topical antihistamines, benzocaine, neomycin or bacitracin, which can cause their own allergic reactions. Over the counter hydrocortisone (1%) is not effective.
- Wash all your gear. Wear non-latex disposable gloves (the resin can penetrate latex/rubber). Use grease-cutting dish soap or alcohol for solid objects, and machine wash clothing with regular detergent, unless the urushiol is so heavy it turned black, in which case you must throw it out.
- Avoid soaps with moisturizers and oils when showering. Clean under fingernails, where urushiol can hide and be distributed by scratching.
- There are a variety of home treatments, including topical use of Burrows solution, baking soda, oatmeal baths, calamine lotion, and kaolin. Oral OTC antihistamines are generally not effective. Severe cases may require prescription antihistamines, topical corticosteroids or oral steroid medication. See your doctor immediately for these if needed.
is an Emergency Medical Technician and an Outdoor Emergency Care instructor for the National Ski Patrol. He welcomes your questions on first aid practices.