The Osarten H 12.5 mg/20 mg Tablet combines two medications. It aids in the management of hypertension in a variety of ways. Olmesartan and hydrochlorothiazide are the two medications that make up the Osarten H 12.5mg/20mg Tablet. It is typically used when blood pressure cannot be adequately controlled by a single medication. Olmesartan facilitates easier blood flow by relaxing and enlarging your blood vessels. Your blood pressure will drop as a result. As a diuretic (water pill), hydrochlorothiazide lowers blood pressure by increasing urine production. Controlling your blood pressure lowers your chances of kidney issues, heart attacks, and strokes. For the medication to work, it must be taken as directed on a regular basis.