Poison ivy: How effective are available treatments?
In this study, only one treatment approach significantly reduced pruritus. Three approaches were often associated with recurrences of rash or symptoms.
We assumed that an average of 4 categories of treatment would be tried (eg, topical corticosteroids, systemic corticosteroids, topical antihistamines, and other topical agents), and that the mean number of days until resolution would be 21, with a standard deviation (SD) of 4 days. Setting power at 80% and alpha at .05, we calculated it would take 105 patients per group (N=420) to detect a difference of 2 days in time until resolution.
RESULTS
Over the 5-year study period, 36 clinicians identified 186 patients who expressed an interest in the study, and they transmitted the patient contact information to the research team. Patients were seen in a traditional primary care setting. All 186 patients were enrolled by phone. However, only 89 completed and returned their diaries and signed consent forms; of these, 60% were female, 92% were white, 4% were black, 4% were American Indians, 2% were Hispanic, and 7% had diabetes mellitus.
Five practices contributed data on numbers of poison ivy encounters per month and total encounters per month for the year 2013. They included an inner city academic practice in central Oklahoma and a rural community health center, a suburban private practice, and 2 private practices in a town of 30,000 in eastern Oklahoma. The largest average number of encounters occurred between April and August.
The distribution of enrolled-patient visits by month and season corresponded roughly to the proportions of all patient visits for poison ivy, with 1% occurring in the winter, 35% in the spring, 55% during the summer, and 9% in the fall. Virtually all study participants (92%) complained of pruritus and had erythema (91%) and papules (87%). Forty-nine percent had vesicles or bullae. The area of the body most often affected was the head/face/neck, 61%, followed by the trunk, 56%; legs, 54%; and arms, 22%.
From the date of initial clinical consultation, the mean/median (SD; range) duration of symptoms and signs were: pruritus, 10.9/9 days (7.1; 0-43); erythema, 13.7/13 days (7.7; 0-42); papules, 10.1/9.5 days (6.5; 0-37); and vesicles, 5.3/5 days (4.1; 0-15). The mean/median (SD; range) duration of any symptom or sign was 14.4/13.5 days (8; 1-43). Rashes with vesicles tended to last longer (16.1 vs 12.9 days), but this difference did not reach statistical significance.
Treatments used by patients before and after their primary care visit are shown in TABLE 1. Seventy-three percent of patients had tried something from one treatment category before consulting a clinician, and 31% had tried something from more than one category. They were most likely to have used a topical antipruritic, astringent, or low-potency corticosteroid, or a combination of these. Clinicians always recommended some treatment and, in 76% of cases, treatments from more than one category. They most often prescribed oral or parenteral corticosteroids (81% of the time), sometimes in combination with a high-potency topical corticosteroid (25% of the time) or oral antihistamine (31%).
