Alpha blockers are a type of blood pressure medicine. They stop a hormone called norepinephrine from tightening the muscles in the walls of smaller arteries and veins. So the blood vessels remain open and relaxed. This improves blood flow and lowers blood pressure.

Alpha blockers also relax other muscles in the body. So the medicines sometimes are used to treat symptoms of other conditions, such as an enlarged prostate.

Other names for alpha blockers are:

• Alpha-adrenergic blocking agents.
• Alpha-adrenergic antagonists.
• Adrenergic blocking agents.
• Alpha-blocking agents.
• Alpha-1 blockers.

Types of alpha blockers

Alpha blockers may be short acting or long acting.

• Short-acting medicines work quickly. But their effects last only a few hours.
• Long-acting medicines take longer to work. But their effects last longer.

The alpha blocker that’s best for you depends on your health and the condition being treated.

Examples of alpha blockers used to treat high blood pressure include:

• Doxazosin (Cardura).
• Prazosin (Minipress).
• Terazosin (Tezruly).

When alpha blockers are used

Alpha blockers usually aren’t the first treatment for high blood pressure. Instead, they’re used with other medicines, such as diuretics, when high blood pressure is hard to control.

Alpha blockers also may help improve urine flow in older men with an enlarged prostate, also called benign prostatic hyperplasia.

Side effects

When you start taking an alpha blocker, you might have low blood pressure and dizziness. This may make you faint when you stand after sitting or lying down. You might be told to take your first dose at bedtime.

Other possible side effects are:

• Headache.
• Fast or pounding heartbeat.
• Weakness.

Before taking an alpha blocker, tell your healthcare team about all the medicines you take. Alpha blockers may affect how some other medicines work. Make sure you tell your healthcare team if you take beta blockers, calcium channel blockers, or medicines for erectile dysfunction.

Alpha blockers may improve total cholesterol. But some studies show that long-term use of some alpha blockers might increase the risk of heart failure. Talk with your healthcare team if you have questions about the medicines you take.