Co-Micardis 80/12.5 mg tablets contains Telmisartan 80 mg and hydrochlorothiazide 12.5 mg. Both of these substances help to control high blood pressure.(hypertension). Telmisartan belongs to a group of medicines called angiotensin II receptor antagonists. Angiotensin-II is a substance produced in your body which causes your blood vessels to narrow thus increasing your blood pressure. Telmisartan blocks the effect of angiotensin II so that the blood vessels relax and your blood pressure is lowered. Hydrochlorothiazide belongs to a group of medicines called thiazide diuretics which cause your urine output to increase leading to a lowering of your blood pressure.