Digoxin Interactions

Licorice (Glycyrrhiza glabra) contains glycyrrhizin, which inhibits the renal enzyme 11-beta-hydroxysteroid dehydrogenase type 2 and produces mineralocorticoid-like potassium loss. The resulting hypokalemia increases the heart's sensitivity to digoxin, raising the risk of digoxin toxicity and dangerous arrhythmias.

St. John's wort revs up a gut transporter that digoxin depends on for absorption, so combining them quietly drains digoxin from the bloodstream. Because digoxin has so little room to spare, that drop can leave the drug too weak to control your heart.

Glycyrrhizin in licorice inhibits the kidney enzyme 11-beta-hydroxysteroid dehydrogenase type 2, producing a state of apparent mineralocorticoid excess that causes sodium retention and potassium loss. The resulting low potassium makes the heart more sensitive to digoxin and can trigger toxic arrhythmias even when serum digoxin levels look normal.

Hawthorn (Crataegus) shares digoxin's cardiac target and can cross-react with the immunoassays used to monitor digoxin, so a serum level may read falsely high or low. Controlled testing shows little change in how much digoxin reaches the bloodstream, so the practical concerns are additive cardiac effects and confounded lab monitoring rather than altered absorption.

Dairy is a dietary source of calcium, and calcium status modestly influences how digoxin acts on the heart. The dietary-dairy effect is minor on its own; the more relevant scenario is large stacked calcium loads (dairy plus supplements plus calcium-containing antacids) or intravenous calcium in a hospital setting. Milk proteins may also slightly reduce digoxin absorption from oral doses, but the effect is small and usually not clinically meaningful.

There is no major direct chemical clash between alcohol and digoxin, but alcohol works indirectly to make digoxin less safe. Alcohol can trigger irregular heart rhythms (so-called holiday heart) and, along with diuretics, deplete potassium and magnesium. Because digoxin has a narrow safety margin, those electrolyte shifts make the heart more sensitive to it and raise the risk of digoxin toxicity. Heavy drinking can also worsen the heart failure digoxin is meant to treat.