Recurrent herpes labialis during isotretinoin therapy: is there a role for photosensitivity?

Isotretinoin (13-cis-retinoic acid) is one of the synthetic retinoids derived from vitamin A. Vitamin A derivatives demonstrate virucidal activity, both in vivo and in vitro. Isotretinoin has been used for the treatment of recurrent herpes simplex with encouraging results. However, we present a case with frequent attacks of herpes labialis during isotretinoin therapy for acne, who had a marked decrease in frequency of recurrences following strict use of sunscreens.