Medicine for the Outdoors
Medicine for the Outdoors

Dr. Paul Auerbach is the world's leading outdoor health expert. His blog offers tips on outdoor safety and advice on how to handle wilderness emergencies.

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Poison ivy (oak and sumac) season will soon arrive, and much will be written in the press about remedies for the itchy rash caused by exposure to urushiol, the resin found in these plants. In addition to the standard method of washing with soap and water, there are commercial products touted to facilitate physical removal of the oily resin, which theoretically reduces the exposure and lessens the skin reaction.

One such product is Zanfel™ Poison Ivy, Oak & Sumac Wash. Zanfel™ is sold in 1 ounce tubes, and is advertised to carry a 10 year shelf life. Instructions for use direct the user to:

1. Wet the affected area.
2. To treat a surface area of skin approximately the size of an adult hand or face, squeeze 1 and 1/2 inches of Zanfel™ from the tube into the palm of a hand. Do not use less than this amount.
3. Wet and rub both hands together for 10 seconds, working the Zanfel™ into a paste. This activates the ingredients.
4. Using both hands, rub the activated Zanfel™ onto the affected skin for 3 minutes or until there is no itching.
5. Rinse the area thoroughly with running water.
6. If itching returns, repeat the process.

The manufacturer states that Zanfel™ is "safe and effective during any stage of the allergic reaction," is "safe for face and genitals," and is "safe for children and pregnant or nursing women."

Zanfel™ is a soap mixture of ethoxylate and sodium lauroyl sarcosinate surfactants. When "activated" (worked into a paste that can be spread effectively on the skin), the soap is able to bind urushiol and thus allow it to be removed from the skin by rinsing.

Zanfel™ is unique with respect to poison ivy/oak/sumac remedies in that it is supposed to remove resin from the skin after the rash has appeared. In one study, this effect was present even at 144 hours post exposure. However, it seems logical that at some point post exposure, urushiol is no longer present in the skin and that the allergic contact dermatitis (manifested as redness, itching, swelling, and blisters), would not be lessened by Zanfel™, unless it has some direct anti-inflammatory properties. The exact duration of the period during which Zanfel™ would be expected to be effective has not been determined, but its effectiveness is likely greatest nearest the time of initial exposure to urushiol. It is possible that used within the first few hours of exposure, a reaction might be prevented.

It should be noted that relative to many other drugs and remedies on the market, there are few clinical studies using Zanfel™. While the data referenced by the company are supportive, it is possible that repeat or larger studies might be less conclusive. That having been said, there does not seem to be any harm in using this product, and there may be significant benefit. The user is cautioned that no therapy, including Zanfel™, is infallible, so that if a person suffers a serious reaction to poison ivy, oak, or sumac, physician attention may be necessary. The most potent treatment currently available is high-dose steroid administration, which should be done under the guidance of a medical professional, unless one is far from help (e.g., in the wilderness).

Anecdotally, a few of my medical colleagues have used Zanfel™, both for themselves and for patients, and have found it to be effective, in that they believe that the reaction to a known poison oak/ivy/sumac plant(s) has been lessened (in comparison to what they would have expected), and in some cases halted, after application of the product. Other providers, like myself, await their first opportunity to use Zanfel™.

Preview the 25th Anniversary & Annual Meeting of the Wilderness Medical Society, which will be held in Snowmass, Colorado July 25-30, 2008.

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About the Author

Dr. Paul S. Auerbach is the world’s leading authority on wilderness medicine.