Potassium Iodide as a Cause of Prolonged Fever

A 73-year-old man was initially seen with a 15-year history of intermittent fevers and had been treated for culture-negative subacute bacterial endocarditis. He had been taking potassium iodide as a bronchorrheic agent for approximately the same 15-year period, and, when potassium iodide therapy was discontinued, the fever resolved and has not recurred during 2½ years of observation. The possible mechanisms of fever caused by potassium iodide and current clinical indications for potassium iodide use are described.