What Medications Are Used to Treat an Enlarged Prostate (BPH)?

Alpha Blockers Relax Smooth Muscle in the Prostate

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You may have heard that Flomax, which is taken for treatment of enlarged prostate, or benign prostatic hypertrophy (BPH), can cause vision problems over time. You may also be wondering about the efficacy and safety of BPH drugs in more general terms.

Alpha Blockers: How Do Alpha Blockers Work?

Alpha blockers work by relaxing the smooth muscle tissue in your prostate and at the opening to your bladder.

When this muscle tissue relaxes, it is easier for your urine to flow. This may help if you have difficulty starting to urinate and a weak urine stream.

Alpha blockers can start working within two to three days, and may relieve your urinary symptoms in about two to three weeks. However, these medications do not stop your prostate gland from continuing to enlarge.

Available alpha blockers include:

  • Cardura (doxazosin)
  • Flomax (tamsulosin)
  • Hytrin (terazosin)
  • Uroxatral (alfuzosin)

What Are the Side Effects of Alpha Blockers?

Side effects may vary with the specific medication you are taking and will go away when you stop the medication. Each alpha blocker has slightly different side effects, which are usually mild, including:

  • Weakness or tiredness
  • Low blood pressure
  • Lightheadedness and dizziness
  • Stuffy or runny nose
  • Headaches
  • Stomach aches or pains

You may also notice less semen when you ejaculate. The alpha blockers may cause retrograde ejaculation, which is the ejaculation of all or some of your semen into your bladder instead of out through your penis.

Although you may find this upsetting, it is not harmful.

You may not be able to use an alpha blocker if you have erectile dysfunction and are using a medication to treat your condition. An alpha blocker can lower your blood pressure to unhealthy levels if you take it along with a mediation to treat erectile dysfunction, such as Viagra (Sildenafil), Levitra (vardenafil) or Cialis (tadalafil).

Does Flomax Cause Eye Problems?

The alpha blockers, including Flomax, do not affect vision or eye health. However, an eye problem called the floppy iris syndrome can occur in men who are taking or who have recently taken Flomax when they are having cataract surgery. Your eye surgeon (ophthalmologist) can make modifications in your cataract surgery, if needed.

5-Alpha Reductase Inhibitors: How Do 5-Alpha Reductase Inhibitors Work?

The 5-alpha reductase inhibitors work by interfering with the effect of specific male hormones (androgens) on your prostate. This may slow the growth of your prostate and can even cause your prostate to get smaller, which may help improve BPH symptoms.

Men with larger prostates may have a greater benefit from these medications than do men with smaller prostates. But, for some men, size (of the prostate that is) does not matter, and the 5-alpha reductase inhibitors may not give satisfactory results even if your prostate gets smaller.

The 5-alpha reductase inhibitors work slowly, and they may take up to six months before you notice any improvement.

Available 5-alpha reductase inhibitors include:

  • Avodart (dutasteride)
  • Proscar (finasteride)

What Are the Side Effects of 5-Alpha Reductase Inhibitors?

Side effects of the 5-alpha reductase inhibitors are uncommon, and these medications appear to be safe and well tolerated.

Side effects include:

  • Difficulty getting an erection
  • Decreased desire to have sex (decreased libido)
  • Smaller amount of semen releases during ejaculation
  • Tenderness or enlargement of the breasts

Avodart and Proscar can be taken with medications for erectile dysfunction.

5-Alpha Reductase Inhibitors and PSA

Both Avodart and Proscar lower prostate-specific antigen (PSA) levels in your blood. Your doctor needs to know if you are taking one of these medications so she can properly interpret your PSA test results. This is important because PSA levels are used to detect early-stage prostate cancer.

Can I Take Both an Alpha Blocker and a 5-alpha Reductase Inhibitor?

Depending on your symptoms and the size of your prostate, your doctor may recommend a combination of an alpha-blocker with a 5-alpha reductase inhibitor.

The combination of the two types of medications may help your symptoms more than either medicine alone.

More Information


AUA Practice Guidelines Committee. AUA guideline on management of benign prostatic hyperplasia. Chapter 1: Diagnosis and treatment recommendations. Journal of Urology 2003, 170:530–547.

McConnell JD, et al. The long-term effect of doxazosin, finasteride, and combination therapy on the clinical progression of benign prostatic hyperplasia. New England Journal of Medicine 2003, 349:2387–2398.

Roehrborn CG, et al. The effects of dutasteride, tamsulosin and combination therapy on lower urinary tract symptoms in men with benign prostatic hyperplasia and prostatic enlargement: 2-year results from the CombAT study. Journal of Urology 2008, 179:616–621.

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