Desensitization to trimethoprim/sulfamethoxazole in HIV-infected patients

Trimethoprim-sulfamethoxazole (T/S) is an effective and important prophylactic medication for HIV-infected patients that must frequently be discontinued because of allergic reactions.

Our objective was to assess the safety, the frequency of success, and the duration of desensitization to T/S in HIV-infected patients.

We studied oral desensitization with T/S of patients with a history of allergy to the medication and longitudinal follow-up. Twenty-eight men with a history of T/S-induced skin rashes were studied. Mean age was 35 years (range, 26 to 50 years). Mean CD4 count was 89 cells/mm3 (range, 0/mm3 to 210/mm3). Patients were seen every 4 to 6 weeks. Mean follow-up was 19.07 weeks (range 2 to 81 weeks).

After 32 weeks, 23 of 28 (82%) patients were successfully desensitized (four had rashes develop, and one could not continue for personal reasons). Of the 23 patients who were successfully desensitized, six were known to have subsequently discontinued T/S (four had rashes; two discontinued on the advice of their personal primary physicians). Six patients were lost to follow-up. One patient died of pulmonary Kaposi's sarcoma. Ten patients are taking the medication regularly without any problems.

T/S desensitization is a simple, safe and effective means to provide it for most patients with a history of "allergic" rashes.