Hersle K, Mobacken H, Sloberg K, Thilander H
Br J Dermatol. 1982 Jan;106(1):77-80. doi: 10.1111/j.1365-2133.1982.tb00904.x.
A double-blind study of twenty-eight patients with severe oral lichen planus treated with etretinate (75 mg daily) or a placebo for 2 months, showed that the oral retinoid had a marked beneficial effect. Nine non-responders who had received only placebo then entered an open cross-over study and they responded well to etretinate. Etretinate thus provided effective symptomatic relief for severe oral lichen planus, but side-effects were common, and six patients stopped treatment because of them.