The incidence of agranulocytosis during treatment of dermatitis herpetiformis with dapsone as reported in Sweden, 1972 through 1988.

During the 17-year period 1972 through 1988, a total of seven cases of agranulocytosis associated with the use of dapsone for the treatment of dermatitis herpetiformis were reported in Sweden. The median age of the patients involved was 61 years; three of them were male. The median duration of dapsone treatment was 7 weeks and the daily prescribed dose was 100 mg. Based on sales and prescription data, the crude relative risk of agranulocytosis during dapsone treatment of dermatitis herpetiformis was 50, and the total risk was one case per 3000 patient years of exposure to dapsone. In relation to the number of new cases of dermatitis herpetiformis, agranulocytosis was estimated to develop in 1 of 240 to 425 patients receiving dapsone therapy. Patients should be instructed to seek medical care immediately in case of fever.