Losartan Products | Cleanchem - Losartan is an angiotensin II receptor blocker (ARB) used to treat hypertension, diabetic nephropathy, and heart failure. It works by blocking the action of angiotensin II, resulting in vasodilation and reduced blood pressure. It is well-tolerated and has fewer side effects than ACE inhibitors, particularly avoiding cough. Losartan also has protective effects on the kidneys.