A case of hyperdynamic shock caused by trimethoprim-sulfamethoxazole in which no tumor necrosis factor or features of anaphylaxis were detected.

An unusual acute hypotensive syndrome has been observed in association with administration of trimethoprim-sulfamethoxazole (TMP-SMZ) to patients with human immunodeficiency virus (HIV) infection. In the 11 cases that have been reported, the syndrome differs from classic anaphylaxis and resembles septic shock. Mediation by tumor necrosis factor (TNF) has been hypothesized, but the mechanism has not been characterized with cytokine assays, and no invasive hemodynamic measurements have been reported. We describe a case of recurrent hyperdynamic shock--without classic features of anaphylaxis, without detectable IgE antibodies against TMP or SMZ, and without detectable levels of TNF--involving an HIV-infected patient rechallenged with TMP-SMZ.