Olvance H 20 Tablet is a combination antihypertensive medication containing Hydrochlorothiazide 12.5 mg and Olmesartan Medoxomil 20 mg. Hydrochlorothiazide is a thiazide diuretic that promotes the excretion of sodium and water by inhibiting sodium reabsorption in the distal convoluted tubules of the kidneys, thereby reducing blood volume and lowering blood pressure. Olmesartan Medoxomil is an angiotensin II receptor blocker (ARB) that selectively inhibits the binding of angiotensin II to the AT1 receptor, preventing vasoconstriction and aldosterone secretion, which results in vasodilation and decreased blood pressure. The combination of these two agents provides a complementary mechanism of action for effective management of hypertension. Olvance H 20 is indicated for the treatment of essential hypertension to reduce the risk of cardiovascular events such as stroke and myocardial infarction. It is generally well tolerated, but patients should be monitored for potential side effects including electrolyte imbalances, hypotension, dizziness, and renal function alterations. It is contraindicated in patients with hypersensitivity to either component, severe renal impairment, or during pregnancy. Regular blood pressure monitoring and periodic laboratory tests are recommended during therapy to ensure efficacy and safety.