Management of adverse reactions to prophylactic trimethoprim-sulfamethoxazole in patients with human immunodeficiency virus infection

Background: In hospitals attended by patients with human immunodeficiency virus infection, adverse reactions are often observed to trimethoprim-sulfamethoxazole, particularly cutaneous reactions. Given the importance of this drug for prophylaxis we have attempted to establish a desensitization or tolerance protocol so that patients can continue the drug without repeated adverse reactions. Methods: We studied 34 HIV patients with adverse cutaneous reactions to trimethoprim-sulfamethoxazole, slight to moderate in nature but not life-threatening. Skin tests (prick and intradermal) were done in an attempt to rule out a mechanism of hypersensitivity. Subsequently, trimethoprim-sulfamethoxazole was administered orally in increasing doses beginning with trimethoprim, 0.2 mg, and sulfamethoxazole, 1 mg. The same dose was repeated after 12 hours and then doubled every 24 hours until the therapeutic dose was achieved. If adverse reactions appeared we maintained the last dose administered and administered antihistamines until the reactions cleared or improved. Results: None of the patients had positive skin tests (immediate or delayed). Twenty-seven patients were satisfactorily desensitized. After a follow-up of 3 months, 25 patients were still incident-free on trimethoprim-sulfamethoxazole prophylaxis, and 19 returning for check-ups at 6 months could still tolerate the drug well. Conclusions: Our data indicate that patients with adverse reactions to trimethoprim-sulfamethoxazole can continue prophylactic treatment after oral desensitization.