An immune reaction caused by light rays changing medications in the blood to allergic substances.
A contact dermatitis produced by the interaction between ultraviolet light rays and topically applied chemicals such as sunscreens, perfumes, phenothiazines, sulfonamides, and some components in soaps. Sunlight changes the structure of these chemicals, causing them to become allergens. An eczematous rash results. Avoiding the inciting agent is preventive; topical corticosteroid drugs provide relief from the rash.