Recently we found that 6-methylcoumarin (6-MC), a synthetic fragrance widely used in cosmetics, is capable of inducing contact photoallergy in human volunteers.1 Since exposure to 6-MC must be exceedingly common, we considered that photoallergy to 6-MC must be more common than realized. We now report a case of severe photocontact allergic reaction developing after the application of two popular sunscreens. Both contained 6-MC as an ingredient.
Report of a Case
While vacationing in Jamaica, a 22-year-old woman applied a mixture of two popular sunscreens to her face, chest, and thighs. The active ingredient in one was amyl dimethyl p-aminobenzoate (Escalol 506) and in the other it was homomenthyl salicylate (homosalate). Twenty-four hours later, she noted intense erythema and pruritus, limited to the areas pretreated with the sunscreens. By 48 hours, there was massive swelling and vesiculation, with oozing of the face, and she could not retract her eyelids.
Kaidbey KH, Kligman AM. Contact Photoallergy to 6-Methylcoumarin in Proprietary Sunscreens. Arch Dermatol. 1978;114(11):1709-1710. doi:10.1001/archderm.1978.01640230081024