Contact and photocontact allergy to sunscreens.

Patch and photopatch test studies in 23 patients with reactions to sunscreen preparations revealed 17 photopatch and 38 patch test-positive reactions. The offending allergens could be traced in 18 of the 23 patients. Allergy to PABA was demonstrated in 11 patients, 5 of whom had photocontact allergy. Photocontact allergy to oxybenzone was seen in 3 patients, while 8 were sensitive to cinnamates, and 2 of these had a photocontact allergy. Six patients were sensitive to the PABA-derivatives octyldimethyl-PABA and amyldimethyl-PABA and the ester glyceryl PABA, 2 of whom had a photocontact allergy. None of the 3 patients with benzocaine sensitivity, including 2 with a photocontact allergy, reacted to the PABA-ester. Eight patients were sensitive to different cinnamates, including 2 cases of photocontact allergy. In one patient sensitivity to two azo-naphthol dyes, contained in a sunscreen preparation, was confirmed. Five other patients had positive skin test reactions to different sunscreen preparations but the offending allergen could not be traced. Thirteen of the 23 patients had chronic light sensitive disorders such as polymorphic light eruption (PMLE) or persistent light reactivity (PLR). Sunscreen sensitivity appears to be more common than previously reported.