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Erythema on dorsa of hands, nail changes in patients with acne
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A 14-year-old girl presents to your office with concern about a rash on her hands. The rash started 3 days ago and was initially tender. Physical exam shows erythematous patches over the dorsa of the hands, accentuated over the second and third MCP joints bilaterally (Figure 1). She is currently on doxycycline 100 mg twice a day and tretinoin 0.05% cream every night at bedtime for acne vulgaris. She is otherwise healthy and taking no other medications. She is a pitcher for her school’s softball team and had a tournament the weekend before presenting to your office. The tournament was in town; she denies recent travel.
Carrie C. Coughlin
Marissa J. Perman
Your next patient is a 15-year-old boy who presents with nail changes. A few weeks ago, he started noticing color change of all of his fingernails and lifting of the nail plates from the nail beds. Physical exam shows subungual hemorrhage and onycholysis of the fingernails (Figure 2). The nails are all affected distally; the proximal nails and nail folds remain normal. He denies recent illness or travel. He takes doxycycline 100 mg twice daily for acne. He is otherwise healthy. He runs track; the season started 1 month ago.
Can you spot the rash?
Diagnosis: Phototoxicity (sunburn and photo-onycholysis) secondary to doxycycline.
Case Discussion
Tetracycline antibiotics are commonly used in dermatology. Their anti-inflammatory properties and few serious side effects have made them the mainstay of oral treatment of acne. Additionally, they are effective in treating rosacea, cutaneous staphylococcal infections and several systemic infections. Of the tetracyclines, demeclocycline is the most photo-sensitizing and is not routinely prescribed by dermatologists.
Figure 1. Erythema of the dorsa of the hands of a 14-year-old girl following exposure to sunlight while on doxycycline.
Photo courtesy of Yan AC
Doxycycline and minocycline are the most commonly prescribed tetracyclines by US dermatologists. Doxycycline is much more likely to be photosensitizing for patients than minocycline. Photosensitizing effects include exaggerated sunburn and onycholysis, as well as a polymorphous light eruption-like rash. The phototoxic effects are presumed to be dose-related, but even low-dose doxycycline can trigger photo-onycholysis.
Photo-onycholysis due to medications is a phototoxic reaction. Psoralens and fluoroquinolone antibiotics are other common causes of photo-onycholysis. Nail changes can be seen concurrently while taking a predisposing medication or after stopping the medication.
Medication induced nail changes take several forms. For example, onycholysis is distal separation of the nail plate from the nail bed, as seen in the second patient. Proximal separation of the nail from the nail bed, classically seen after coxsackievirus/enterovirus infections, is called onychomadesis. Pigmentary changes in nails can be seen in photo-onycholysis due to doxycycline, and minocycline can induce hyperpigmentation of the nail beds.
Figure 2. Onycholysis, hyperpigmentation and subungual hemorrhage of the nails of a 15-year-old boy on doxycycline.
Photo courtesy of Yan AC
Several other classes of medications, including antiretrovirals, can cause alterations of pigment in nails. Chemotherapy can cause horizontal, dystrophic ridges (Beau’s lines), onycholysis, onychomadesis and paronychia.
The half-life of immediate-release doxycycline is 18 to 22 hours. Thus, patients who are taking doxycycline for acne treatment are often advised to stop the medication the week before an anticipated prolonged sun exposure (such as vacations to the beach or ski trips). Clearly, this is not an option for patients taking the medication for treatment of infections, so counseling of the potential photo-induced side effects is important. Moreover, patients should be warned that indoor tanning beds can produce similar phototoxic effects in patients taking doxycycline.
In sum, given the widespread use of tetracyclines, especially doxycycline, physicians should be aware of the potential phototoxic side effects of doxycycline and counsel patients appropriately.
References:
Badri T. Acta Dermatovenerol Alp Panonica Adriat. 2004;13:135-136.
Carrie C. Coughlin, MD, is a resident in the division of dermatology, Washington University School of Medicine, St. Louis. She can be reached at ccoughli@dom.wustl.edu.
Marissa J. Perman, MD, is an attending physician at The Children’s Hospital of Philadelphia.