Underrecognized phototoxicity from prolonged doxycycline therapy: a case highlighting early nail involvement

Abstract

A 27-year-old man developed photo-onycholysis and a facial phototoxic rash after taking doxycycline, cefuroxime and aceclofenac for about 40 days following incision and drainage of a wrist abscess. He had no other illness. The wound healed well and his laboratory results were unremarkable, but several fingernails turned reddish-brown and became so tender that light pressure was painful, and both cheeks developed erythematous maculopapular lesions. The toenails were normal. There was no separation of the nail plate, no pitting and no subungual debris, so the usual morphological clues to photo-onycholysis were absent. Other causes were excluded clinically, and of the three drugs he had taken only doxycycline is an established cause of this reaction. Causality assessment using the Naranjo scale gave a score of 5, indicating a probable adverse drug reaction. All three drugs were stopped and the patient was counselled about ultraviolet A protection and nail care; the rash and the nail changes settled over eight weeks without progressing to detachment. Two aspects of the case deserve emphasis. The nail changes were inflammatory and painful but pre-lytic, a stage at which the diagnosis is easily missed, and the reaction occurred during a north Indian winter rather than in summer or in a returning traveller, which is the setting of most published reports. The case is also a reminder that a short course would have sufficed after drainage of an uncomplicated abscess, and that the reaction would not have occurred had the prescription been stopped on time.