Drug Interactions between digitoxin and licorice

GENERALLY AVOID: Chronic use of licorice may potentiate the risk of digitalis toxicity and other cardiovascular complications in patients treated with cardiac glycosides. Glycyrrhizic acid, a component of licorice, can induce hypokalemia, hypernatremia, edema, hypertension, and suppression of the renin-aldosterone system by virtue of its mineralocorticoid activity. In digitalized patients, electrolyte imbalance such as hypokalemia and hypomagnesemia can lead to arrhythmias, while other chronic effects of glycyrrhizic acid can compromise overall cardiovascular condition. In one case report, an 84-year-old man developed congestive heart failure secondary to digitalis toxicity shortly after he began using a Chinese herbal laxative containing licorice 400 mg and rhubarb 1600 mg three times a day. The patient had mitral regurgitation with atrial fibrillation and had been treated with digoxin and furosemide. He recovered 18 days after stopping both digoxin and the herbal laxative.

MANAGEMENT: Patients should consult a healthcare provider before taking any herbal or alternative medicine. In general, chronic use of licorice and licorice-containing products should be avoided in patients treated with cardiac glycosides.