Photocontact dermatitis from P-aminobenzoic acid.

A 6-year-old girl with xeroderma pigmentosum was contact and photocontact sensitized to PABA which had been used as a sunscreening agent. The activating wavelengths for photocontact dermatitis were in long-wave ultraviolet light. The experimental photocontact sensitization was not induced in guinea pigs. Although PABA is the most effective and harmless sunscreening agent for normal skin, it could induce photocontact sensitivity especially in diseased or damaged skin.