Hyzaar contains a combination of hydrochlorothiazide and losartan. Hydrochlorothiazide is a thiazide diuretic (water pill) that helps prevent your body from absorbing too much salt, which can cause fluid retention.
Losartan is a angiotensin II receptor antagonist. Losartan keeps blood vessels from narrowing, which lowers blood pressure and improves blood flow.
Hyzaar is used to treat high blood pressure (hypertension). It is also used to lower the risk of stroke in certain people with heart disease.