Olkem 20H 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 synergistic effect in managing hypertension, improving blood pressure control more effectively than either agent alone. Olkem 20H 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 potential side effects may include dizziness, hypotension, electrolyte imbalance, and renal function alterations. Caution is advised in patients with renal impairment, electrolyte disturbances, or hypersensitivity to sulfonamides. Regular monitoring of blood pressure, electrolytes, and renal function is recommended during therapy. Olkem 20H should be used under medical supervision to ensure optimal therapeutic outcomes.