ABSTRACT
Phototoxicity implies direct photodamage to the skin while the term photoallergy implies an immune mechanism. The frequently used antihistamine diphenhydramine has rarely been reported to cause photoallergy. The responsible wavelengths were found to be in the ultraviolet B (UVB) range. Griseofulvin is well known to induce phototoxicity. Photoallergy to this agent was suggested by passive humoral transfer of sensitivity in one report. The most commonly reported drugs capable of causing photoallergic reactions are the sulfonamides, chlorpropamide, chlorpromazine, promethazine, hydrochlorothiazide, chlorothiazide, chlordiazepoxide, calcium cyclamate, tolbutamide, and griseofulvin. Triclosan is a widely used antibacterial agent in bar soaps and deodorants. Three fragrance ingredients have been associated with photoallergic contact dermatitis: musk ambrette, 6-methylcoumarin, and sandalwood oil. Para-aminobenzoic acid was the first chemical used as a sunscreen. It was the most widely used active agent in sunscreens in the 1960s and early 1970s. Few systemic drugs that produce photosensitivity have been reported to cause photoallergic contact dermatitis.
