Alopecia areata is hair loss caused when the immune system attacks hair follicles, where hair growth begins. Contact immunotherapy may be the most effective treatment for severe alopecia areata.footnote 1 A common medicine used is
DPCP, a liquid, is “painted” on the scalp once a week. The
concentration of the solution is increased at each treatment session until a
mild allergic reaction occurs. Hair growth may appear
within 3 months of beginning treatment.