Phototoxic Reaction to Oral Terbinafine Due to Tinea Capitis in a Child

An 18-month-old boy developed a phototoxic skin reaction to oral terbinafine, used to treat a Microsporum canis fungal scalp infection, after sun exposure. The reaction manifested as erythematous plaques on the scalp, ears, and face, resembling subacute lupus erythematosus. Despite the reaction, terbinafine treatment continued due to persistent fungal infection, with sun exposure strictly avoided. The skin lesions regressed with corticosteroid cream, and immunological tests were negative. This case highlights the rare occurrence of terbinafine-induced photosensitivity and the importance of advising patients about potential sun exposure risks during treatment.