Phototoxic dermatitis is the reaction developing in the sun-exposed areas after systemic intake of a photosensitive agent. The phototoxic reactions that develop with oral drugs resemble sun-burn. The reaction regresses with hyperpigmentation after discontinuation of the drug. Photo-onycholysis and pseudoporphyria are the rare outcomes of drug-related phototoxicity. The main drugs responsible for phototoxic reactions and photo-onycholysis are tetracyclines (particularly doxycyclin and demeclocycline), non-steroidal anti-infl ammatory drugs (propionic acid derivatives) and fl uoroquinolones. Doxycycline is a member of the tetracycline group of antibiotics that are commonly preferred for the treatment of acne vulgaris. In this paper, a 12-year-old female patient who had used rifampicine and doxycycline for brucellosis and who had developed phototoxic dermatitis is presented. There was brown discoloration in the distal part of her all hand nails. On her dermatologic examination, there was a patchy lesion which contained pale, erythematous scabs with irregular borders that were dry and adherent in some sites on her nose and cheeks. In addition, she had brown pigmentation on the distal parts of her hand nails. Biopsy was evaluated as phototoxic dermatitis. The discoloration on her nails was accepted as being photooncholysis. We presented this case due to the rarity of doxycycline-related phototoxic reactions and photo-onycholysis

Keywords: Doxycycline, Photo-onycholysis, Phototoxic dermatitis, Photosensitivity