Losartan Interactions

Losartan blocks the angiotensin II receptor, lowering aldosterone and reducing renal potassium excretion in the same way ACE inhibitors do. Concurrent potassium supplementation can drive serum potassium into the hyperkalemic range, with cardiac arrhythmia risk in patients with kidney impairment, diabetes, or heart failure.

Glycyrrhizin in licorice mimics aldosterone, causing renal sodium and water retention and potassium loss. This pseudoaldosteronism raises blood pressure and counteracts losartan's antihypertensive effect, while also producing hypokalemia that can cause weakness and arrhythmia.

Grapefruit may reduce the conversion of losartan to its active form, decreasing effectiveness.

Hawthorn produces modest blood pressure lowering (roughly 5 to 11 mmHg systolic in clinical trials) through vasodilation and mild ACE-like activity. Combined with losartan, the additive effect could occasionally cause hypotension or dizziness, particularly in people on multiple antihypertensives or those starting hawthorn at high doses.