Co-Olesta Tab is a prescription drug used to treat hypertension, commonly known as high blood pressure. By combining the two active ingredients hydrochlorothiazide B.P and olmesartan medoxomil USP, this medicine lowers blood pressure which also lowers the risk of heart attacks and strokes. Olmesartan medoxomil is a member of the angiotensin II receptor blocker (ARB) drug class. It works by selectively inhibiting the activity of the hormone angiotensin II, which constricts blood vessels. Olmesartan medoxomil induces the blood vessels to relax and widen, promoting smoother blood flow throughout the body by preventing the binding of angiotensin II to its receptors. By allowing the blood vessels to relax, the heart is put under less stress and blood pressure is lowered.