BMJ  2004;329:265 (31 July), doi:10.1136/bmj.329.7460.265

Paper

DRUG POINTS

Photo-onycholysis associated with the use of doxycycline

¹ Netherlands Pharmacovigilance Centre Lareb, Goudsbloemvallei 7, 5327 MH 's-Hertogenbosch, Netherlands, ² Herenweg 40, 2101 ML Heemstede, Netherlands

The Netherlands Pharmacovigilance Centre Lareb received five reports concerning photo-onycholysis associated with the use of doxycycline (table). All five patients used 200 mg of doxycycline a day for the prophylactic treatment of Lyme disease after tick bite. In all cases the affected nails had been exposed to the sun during the summer. All patients showed (partial) recovery after several months. To our knowledge, no other factors (either specific physical disorders or concomitant drug use) were responsible for the onycholysis in these patients.

View this table: [in this window] [in a new window]   Reports of photo-onycholysis associated with the use of doxycycline*

 

Although the association between doxycyline and onycholysis has been sparsely reported,^1-3 the circumstances of the patients we report differ from those described elsewhere. All five patients used doxycycline exclusively for the prophylactic treatment of Lyme disease; we did not find any studies that suggested a possible connection between Lyme disease and onycholysis.

The mechanism of this phototoxic reaction is not fully understood. The nail bed is relatively unprotected from sunlight and contains less melanin (implicating less ultraviolet protection) than other skin sites. Onycholysis may, therefore, be the sole expression of a photosensitivity reaction.⁴ Photosensitisation to doxycycline may be mediated by excited state oxygen singlets and free radicals, which arise because ofirradiation with ultraviolet A. This may cause selective injury to mitochondria, the preferential intracellular site of localisation of doxycycline.⁵

Borrelia burgdorferi—which causes Lyme disease—is becoming a more common coinfecting pathogen, and doctors are developing an increased knowledge and awareness concerning the potential risks of tick bites. Due to these developments, more high dosages of doxycycline may be prescribed more often. Considering the relatively good health of the patients using doxycycline for the given indication, exposure to sunlight is the likely cause of onycholysis. These patients should avoid exposure of their nails to the sun shortly after using doxycycline.

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Funding: None.

Competing interests: None declared.

References

1. Yong CK, Prendiville J, Peacock DL, Wong LT, Davidson AG. An unusual presentation of doxycycline-induced photosensitivity. Pediatrics 2000;106: E13.
2. Cavens TR. Onycholysis of the thumbs probably due to a phototoxic reaction from doxycycline. Cutis 1981;27: 53-4.[Web of Science][Medline]
3. Frank SB, Cohen HJ, Minkin W. Photo-onycholysis due to tetracycline hydrochloride and doxycycline. Arch Dermatol 1971;103: 520-1.[Abstract/Free Full Text]
4. Bruinsma W. Nail changes due to drugs. In: Bruinsma W, ed. A guide to drug eruptions. 7th ed. Amsterdam: Intermed, 2000: 26.
5. Shea CR, Olack GA, Morrison H, Chen N, Hasan T. Phototoxicity of lumodoxycycline. J Invest Pharmacol 1993;101: 329-33.

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This article has been cited by other articles:

• Croft, A. M., Jackson, C. J., Darbyshire, A. H., Hasin, T., Davidovitch, N., Cohen, D. (2006). Doxycycline for the Prevention of Tick-Borne Relapsing Fever.. NEJM 355: 1614-1615 [Full text]  
• (2004). Nailing Down Doxycycline Photosensitivity. JWatch Infect. Diseases 2004: 7-7 [Full text]  

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