Leukocytosis and left shift associated with quinidine fever

Fever is a well-known side effect of quinidine therapy, but an elevated white blood cell count is considered unusual. Two patients are described who had leukocytosis or a marked left shift in the white blood cell count (or both) in association with quinidine fever. Neither patient had evidence of infection. In each of these patients, the temperature and white blood cell count returned to normal within two days after quinidine was discontinued. Although infection should always be considered in a patient with fever, leukocytosis, and a left shift, these may also appear in association with quinidine therapy.