Beta blockers act by blocking the beta adrenergic receptors in the sympathetic nervous system which results a reduction in systolic pressure, heart rate, cardiac contractility and output. Beta blockers are routinely used to treat hypertension and to reduce the risk of cardiovascular disease and stroke. Thiazide diuretics decrease active re-absorption of sodium and chloride ions by inhibiting the sodium/chloride co-transporter in the distal convoluted tubule. They also increase potassium ion loss. Thiazide diuretics decrease the blood volume by diuresis and are used in the treatment of hypertension. The combination of a beta blockers with thiazide diuretic results in additive antihypertensive effect compared to using either agent alone.