Doxycycline-induced photo-onycholysis

Journal of Drugs in Dermatology,  Dec, 2003  by Lisa A Carroll,  Anne E Laumann

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ABSTRACT

An uncommon manifestation of phototoxicity, photo-onycholysis results in the separation of the distal nail from the nail bed. Photo-onycholysis may follow the use of various medications or may occasionally be idiopathic. We present a case of photo onycholysis in a patient treated with doxycycline for acne vulgaris.

Introduction

Photo-onycholysis is a phototoxic reaction resulting in the separation of the distal nail from the nail bed. Photo onycholysis may occur after the administration of multiple medications. Occasionally, photo-onycholysis may be idiopathic.

Case Report

A 19 year-old fair-skinned Caucasian female started treatment with doxycycline 100 mg BID in mid-August for acne vulgaris. In late August, she developed a blistering sunburn affecting her face, chest, and extremities after spending a full day on the beach in Chicago. At the beach, the patient's fingernails became painful, especially while swimming. This fingernail pain resolved the next day. In the following weeks, the fingernail pain recurred whenever the patient bumped her nails into objects. At a clinic visit in late September, all 10 fingernails were tender upon palpation. The nails were a light tan color, but were attached distally. By mid October, distal onycholysis had become apparent. On physical examination in mid October, the distal 1/3 to 2/3 of all 10 fingernails exhibited half-moon shaped onycholysis with resultant yellow white nail discoloration. There were no nail pits or oil spots, The toenails appeared normal except for onycbolysis of the right 3rd toenail. Physical examination otherwise was unremarkable.

This patient, with no pertinent past medical history, was not taking any medications other than doxycycline at the time of her blistering sunburn and subsequent photo-onycholysis. Doxycycline was discontinued in late September. The patient's photo-onycholysis resolved as her nails regrew. She now has normal, attached nails.

Discussion

Onycholysis has many potential causes, including cutaneous disease (psoriasis), congenital conditions (pachyonychia congenital systemic disease (hypothyroidism), drugs, trauma, or nail infection (1). It may also be idiopathic. Photo-onycholysis is an uncommon manifestation of phototoxicity involving separation of the distal nail from the nail bed. Photo-onycholysis is a well-recognized complication of the administration of the tetracyclines, in particular demethylcblortetracycline (2-4). Orentriech reviewed the incidence of phototoxicity in a group of 108 patients taking demethylchlortetracycline. He found that 27 patients experienced exaggerated sunburn-like reactions suggestive of photosensitivity and 7 patients experienced onycholysis with accompanying abnormal skin reactions (4). Other tetracyclines, including doxycycline (5,6,7), tetracycline (5,8,11). minocycline (12), and oxytetracycline (13) have more rarely been reported to induce photo-onycholysis, Photo-onycholysis may also follow the use of fluoroquinoloncs, (5,14) psoralens (5,16), oral contraceptives (17), chlorazepate dipotasslum (18), quinine (19), and benoxaprofen (20,21). Occasionally, photo-onycholysis has no apparent cause.

Photo-onycholysis usually appears after at least 2 weeks of exposure to the offending medication. Photo-onycholysis secondary to a medication usually occurs in association with a generalized phototoxic reaction but it can occur in the absence of a skin reaction (5). The time between the photosensitive skin manifestation and onset of photo-onycholysis may vary from a few days to six weeks (4,5,22). The onycholysis often affects the distal third of the nail with some sparing of the lateral margins. Pain preceding photo-onycholysis has only been reported with the use of tetracycline derivatives and PUVA (23,24). The mechanism of photo-onycholysis is uncertain. Lewis and Montgomery, who investigated the histopatbologic effects of solar radiation on the nailbed over 50 years ago, found greater elastic tissue degeneration in the nailbed than in adjacent glabrous skin. They felt that this indicated that the nail-plate offers only poor protection m the nailbed from sunlight exposure and may even concentrate the sun's rays (25,26). Photo-onycholysis appears to be caused by UVA light, since experiments have shown that only long wave UVA is transmitted through nails to any significant extent (27). The prognosis for photo-onycholysis is good. with improvement of the nails in 2 to 3 months and complete resolution of the onycholysis within 1 year.

The diagnosis of photo-onycholysis secondary to doxycycline in our patient was based on the occurrence of a sunburn after one to two weeks of treatment with doxycycline, with subsequent onycholysis occurring within three to four weeks of the phototoxic skin erythema. The occurrence of onycbodynia in this patient also supports a diagnosis of doxycycline-induced photo-onycholysis since onychodynia has only been reported to occur in patients with onycholysis secondary to tetracyclines and PUVA. Although the patient did have onycholysis affecting the third right toenail with a clear history of injury to that nail, there was no history of fingernail trauma. Finally, the patient lacked the stigmata of psoriasis. As expected, the patient's onycholysis resolved with regrowth of normal nails.