Angiotensin II Receptor Blockers (ARBs) are drugs most often prescribed for people who experience side effects with ACE inhibitors. They are used to treat high blood pressure and heart failure. Rather than lowering levels of angiotensin II (as ACE inhibitors do), angiotensin II receptor blockers prevent this chemical from having any effects on the heart and blood vessels. The blood vessels are relaxed, which increases the supply of blood and oxygen to the heart muscle. The blood pressure is also reduced. (Also known as Angiotensin-2 Receptor Antagonists).