Descriptions Telmisartan and hydrochlorothiazide combination is used to treat high blood pressure (hypertension). High blood pressure adds to the workload of the heart and arteries. If it continues for a long time, the heart and arteries may not function properly. This can damage the blood vessels of the brain, heart, and kidneys, resulting in a stroke, heart failure, or kidney failure. A lower blood pressure can reduce the risk of strokes and heart attacks. Telmisartan is an angiotensin II receptor blocker (ARB). It works by blocking a substance in the body that causes the blood vessels to tighten. As a result, telmisartan relaxes the blood vessels. This lowers blood pressure and increases the supply of blood and oxygen to the heart. Hydrochlorothiazide is a thiazide diuretic (water pill). It reduces the amount of water in the body by increasing the flow of urine, which helps lower the blood pressure.