Severe, reversible neutropenia during high-dose mebendazole therapy for echinococcosis

Two patients receiving oral high-dose mebendazole therapy for echinococcosis were found to have severe, reversible neutropenia, apparently due to marrow suppression; platelets and RBCs were also reversibly suppressed in one. High blood levels of mebendazole (239 ng/mL) in one patient may have resulted in the neutropenia and several toxic side effects, as well as a striking shrinkage of the patient's pulmonary and liver cysts. Neutropenia with high-dose mebendazole therapy may occur in up to 5% of patients and may be much more common than previously recognized. The WBC count should be monitored frequently during the first several weeks of therapy. Further experience will be needed to determine whether neutropenia is related to mebendazole levels.