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What Are Alpha Blockers?


Updated June 09, 2014

Senior's hand holding prescription pills
Steven Errico/Photographer's Choice RF/Getty Images

Alpha blockers are a type of medicine sometimes used to treat high blood pressure. They are not usually used alone, and many patients are more familiar with alpha blockers because they are used to treat other illnesses, including:

  • Enlarged Prostate (benign prostatic hypertrophy)
  • Pheochromocytoma (a type of hormone-secreting tumor)
  • Peripheral artery disease (poor circulation, usually in the legs)

While other medicines are usually tried before considering alpha blockers, for some patients they represent an important treatment option.

How Alpha Blockers Work:

Alpha blockers, also called alpha adrenergic blocking agents, work by interferring with the transfer of messages to specific parts of the body. Like other "blocker" medications, alpha blockers attach themselves to molecules in the body that serve as receptors for certain chemical messages. Because the chemical message is then prevented from reaching its target, it is said to be blocked.

Alpha blockers block targets called alpha receptors, which are found on blood vessels, in the prostate, and in special blood pressure sensors called baroreceptors.

Patients are usually told to take alpha blockers before bed.

Names of Common Alpha Blockers:

Many different alpha blockers are available. Some commonly prescribed alpha blockers include:

  • Doxazosin (Cardura)
  • Phentolamine
  • Tamsulosin (Flomax)
  • Terazosin

Other alpha blockers are availabe, both within the U.S. and around the world. However, the vast majority of prescriptions in the U.S. are for the drugs listed above. Other types of alpha blockers are used mainly in special circumstances or controlled hospital settings.

Side Effects of Alpha Blockers:

Alpha blockers tend to be well tolerated, but have some important side effects. These include:

  • Dizziness
  • Fainting
  • Low blood pressure
  • Sudden blood pressure changes when standing after sitting

In addition to these side effects, an important research study called the ALLHAT Study found that long-term use of alpha blockers seems to increase the risk of heart failure. While this risk is real, it is small, and the main reason that alpha blockers are not used as "first choice" drugs is that, unlike other high blood pressure medicines, they have not been shown to reduce the risk of stroke and heart attack.


Only you and your doctor can decide on a proper medication for treatment of high blood pressure. Be sure to notify your doctor if you are pregant or breastfeeding, and to supply the names of any other medicines and/or suppliments you are taking. Remember to include over-the-counter medicines like aspirin or Advil and herbal/natural suppliments.

  1. About.com
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  3. High Blood Pressure
  4. Treatment & Monitoring
  5. Alpha Blockers for Hypertension/High Blood Pressure

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