Systemic photoprotection.

At present, three classes of compounds are used as systemic photoprotective agents, but only for specific indications, not for general use in healthy individuals. Beta-carotene prevents or lessens photosensitivity in most patients with erythropoietic protoporphyria and in some patients with other photosensitivity diseases. The antimalarial drugs can clear up skin lesions in patients with polymorphous light eruption and solar urticaria who cannot obtain relief with topical sunscreens and in some patients with porphyria cutanea tarda. Oral psoralens and controlled exposure to sunlight or artificial sources of UVA radiation can increase tolerance to sunlight in fair-skinned individuals and in certain patients with vitiligo or polymorphous light eruption.