What is Diovan HCT (hydrochlorothiazide and valsartan)? Hydrochlorothiazide is a thiazide diuretic (water pill) that helps prevent your body from absorbing too much salt, which can cause fluid retention. Valsartan is an angiotensin II receptor antagonist. Valsartan keeps blood vessels from narrowing, which lowers blood pressure and improves blood flow.
Hydrochlorothiazide and valsartan is a combination medicine used to treat high blood pressure (hypertension). Hydrochlorothiazide and valsartan may also be used for purposes not listed in this medication guide.