Hydroxychloroquine sulfate and other antimalarial drugs have been used successfully as adjunctive therapy for patients with cutaneous lesions of dermatomyositis over the past 20 years. An increased incidence of cutaneous reactions to hydroxychloroquine has been postulated to occur in patients with dermatomyositis.

To determine if adverse cutaneous eruptions due to hydroxychloroquine are more common in patients with dermatomyositis than in those with cutaneous lupus erythematosus.

Retrospective, age-, sex-, and race-matched case-control study.

University-affiliated practice.

The study comprised 42 patients with dermatomyositis (39 adults) and 39 age-, sex-, and race-matched adult patients with lupus erythematosus.

Presence or absence of documented drug eruption due to hydroxychloroquine exposure.

Of 39 patients, 12 (31%) with dermatomyositis developed a cutaneous reaction to hydroxychloroquine. Among age-, sex-, and race-matched patients with cutaneous lupus erythematosus, only 1 developed a cutaneous reaction to hydroxychloroquine. None of the reactions observed in our patients resulted in serious morbidity or mortality. Additionally, 4 patients with dermatomyositis who reacted to hydroxychloroquine were treated with oral chloroquine phosphate, 2 of whom also reacted to chloroquine phosphate.

When contemplating antimalarial therapy for dermatomyositis, both the physician and the patient should recognize that non-life-threatening cutaneous reactions may occur in approximately one third of patients and that perhaps one half of those who react to hydroxychloroquine will also react to chloroquine.