Oral desensitization to trimethoprim-sulfamethoxazole in a patient with acquired immunodeficiency syndrome.

Intravenous administration of trimethoprim-sulfamethoxazole (TMS) on three occasions resulted in fever, rash, and wheezing in a 30-year-old man with acquired immunodeficiency syndrome with Pneumocytis carinii pneumonia. Pentamidine administration produced fever, severe myositis, and clinical deterioration, and therefore, desensitization to TMS was attempted. This was done with low doses of oral suspension and then intravenous administration during a period of 60 hours. The patient reacted with fevers, arthralgia, and erythema that cleared 4 days after the desensitization was completed. This single case of successful desensitization to TMS in a patient with acquired immunodeficiency syndrome suggests that the oral route may be useful in similar situations when this drug is urgently needed.