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Alpha blockers

Medically reviewed by Drugs.com. Last updated on Sep 3, 2021.

Alpha blockers are a type of blood pressure medication. They lower blood pressure by preventing a hormone called norepinephrine from tightening the muscles in the walls of smaller arteries and veins. As a result, the blood vessels remain open and relaxed. This improves blood flow and lowers blood pressure.

Because alpha blockers also relax other muscles throughout the body, these medications also can help improve urine flow in older men with prostate problems.

Examples of alpha blockers

Alpha blockers are either short-acting or long-acting. Short-acting medications work quickly, but their effects last only a few hours. Long-acting medications 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.

Alpha blockers are also called alpha-adrenergic blocking agents, alpha-adrenergic antagonists, adrenergic blocking agents and alpha-blocking agents.

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

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

When alpha blockers are used

Alpha blockers typically aren't the first treatment option for high blood pressure. Instead, they're used in combination with other drugs, such as diuretics, when high blood pressure is difficult to control.

In addition to high blood pressure, doctors prescribe alpha blockers to prevent, treat or improve symptoms of an enlarged prostate (benign prostatic hyperplasia).

Side effects

When you start taking an alpha blocker, you might develop low blood pressure and dizziness, which can make you faint when you rise from a sitting or lying position. As a result, the first dose is often taken at bedtime.

Other side effects might include:

  • Dizziness
  • Headache
  • Pounding heartbeat
  • Weakness

Before taking an alpha blocker, be sure your doctor knows about other medications you take, such as beta blockers, calcium channel blockers or medications for erectile dysfunction. Alpha blockers can increase or decrease the effects of other medications you take.

Alpha blockers may improve total cholesterol. However, some research has found that long-term use of some alpha blockers can increase the risk of heart failure.

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