Trimethoprim-Sulfamethoxazole-Induced Pancytopenia: A Case Report.

Pancytopenia is defined as a decrease in all three myeloid cell lines, usually from a precipitating factor such as an autoimmune condition, prescription drug, or several other factors. The etiology of pancytopenia can be determined through laboratory testing, a peripheral blood smear, and a thorough history and physical examination. Trimethoprim-sulfamethoxazole (TMP/SMX, also known by the brand name of Bactrim® or Septra®) is known to cause pancytopenia in rare cases. Still, it has yet to be fully explored or explained in the literature. We present a case of TMP/SMX-induced pancytopenia that swiftly resolved with cessation of the drug and repletion of platelets. This report aims to serve as an example of a severe case of TMP/SMX-induced pancytopenia, its presentation, and medical treatment in the acute care hospital setting.