Efficacy of topical sensitizers in the treatment of alopecia areata

It has been more than 2 decades since the first report of the use of dinitrochlorobenzene to induce hair growth in 2 patients with alopecia areata. Other topical sensitizers, namely squaric acid dibutylester and diphenylcyclopropenone, have been used with variable success. This article reviews the efficacy and safety of the use of topical sensitizers in the treatment of alopecia areata.