Alpha blockers are non-habit-forming medications. They block the effects of certain hormones in the body (e.g., the stress hormones) that could lead to a rapid heartbeat.

They are called alpha blockers because they block the microscopic areas in the heart called alpha receptors. These alpha receptors are normally activated by certain chemicals in the brain, such as the hormones released during stress (e.g., adrenaline). When activated by these chemicals, the alpha receptors trigger a reaction that speeds the heart rate, increases the force of the heartbeat and constricts the blood vessels. However, this reaction cannot be triggered if the chemicals are blocked by alpha blockers from activating or binding to the alpha receptors.

Therefore, alpha blockers relieve cardiac stress by slowing the heart rate and reducing the force of heart muscle contractions (the pumping action). They also reduce blood vessel constriction in the heart, brain and other parts of the body and therefore belong to a class of drugs called vasodilators.

Because they affect stress hormones, alpha blockers result in a lowering of blood pressure (the force of blood against artery walls). However, they are less commonly used in the treatment of high blood pressure (hypertension) because they may increase the risk of heart failure with long-term use and are associated with relatively strong side effects.

The link between heart failure risk and alpha blocker use was one of the findings of the landmark ALLHAT study (Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial). The largest antihypertensive trial to date with more than 42,000 participants, ALLHAT determined that thiazide diuretics were the preferred “first line” treatment for high blood pressure because they were the most effective at also lowering the risk of heart attack, stroke and other heart diseases. Calcium channel blockers or ACE inhibitors were recommended for patients who could not take diuretics. ALLHAT also noted that many patients need a combination of multiple antihypertensive medications.

There are two types of alpha blockers, which are classified according to the type of alpha receptor that they block (alpha 1 or alpha 2):

Alpha blockers include medications such as the following: