A markedly seasonal dermatitis, characterized by erythema, edema, vesiculation, and crusting, occurs among American Indians. The possibility of preventing it by administration of methoxsalen was studied in 13 members of a group of Chippewa Indians living in Minnesota. The course of the dermatitis during two-week periods of medication with methoxsalen was compared with its course during periods of placebo administration. The results showed that regardless of medication most patients improved under limited controlled exposure to sunlight whereas in outpatients methoxsalen, in a dosage of two 10-mg. capsules per day by mouth, caused a worsening of the condition in six of the nine patients evaluated. Lactose produced a variety of responses in 10 patients. Since the most important etiological factor in the dermatitis was exposure to sunlight, the wearing of wide-brimmed hats and other protective covering was advised as the logical method of prevention and treatment.
Schenck RR. CONTROLLED TRIAL OF METHOXSALEN IN SOLAR DERMATITIS OF CHIPPEWA INDIANS. JAMA. 1960;172(11):1134-1137. doi:10.1001/jama.1960.03020110018005