Poison Ivy Withstands Washing

Abstract

PURPOSE: Poison ivy dermatitis is an allergic skin reaction that plagues outdoor athletes and coaches. No study has yet examined the ideal time to wash off poison ivy after skin exposure. This study hypothesized that the published but untested assertion that poison ivy dermatitis can be avoided with washing within 15 minutes of exposure was true. METHODS: To evaluate this hypothesis, muddled poison ivy was applied to the skin in 8 tape- marked squares. Investigators washed areas, with soapy water, at seven time points: immediately, 5, 10, 15, 30, 45, and 60 minutes. The control square was not washed. Pruritus and erythema were measured daily for 10 days. RESULTS: For allergic subjects, erythema and pruritus developed on all exposed areas except those washed immediately. Erythema was considerably worse on forearms, and increased with more time between the exposure and the washing. Washing 10 minutes after exposure produced less overall erythema (10 day sum) than washing after 60 minutes (p=0.03) CONCLUSIONS:This study represents the first report that only immediate washing after exposure will prevent poison ivy dermatitis. The results demonstrate that washing a poison ivy exposed area will not prevent dermatitis unless washing occurs immediately after contact has been made. Although earlier washing will reduce the severity of the reaction, primary preventative techniques (such as wearing clothing or using barrier creams) are recommended.