Myoclonus and metabolic alkalosis from licorice in antacid

A 90-year-old woman with hypertension developed metabolic alkalosis and myoclonus. Her medications included diltiazem hydrochloride, benidipine hydrochloride, kallidinogenase, procaterol hydrochloride, sennoside, dihydrocodeine phosphate, and KM powder((R)) antacid that contained 354 mg of licorice and 900 mg of sodium bicarbonate per 3.9 g of powder. Endocrinological studies showed slightly reduced plasma renin activity and normal plasma aldosterone concentration. A provisional diagnosis of licorice-induced metabolic alkalosis was established and the patient was successfully treated after correction of serum pH and cessation of the medications. Licorice-induced metabolic alkalosis must be considered in the differential diagnosis of myoclonus.