Medication

Flomax

Generic name: tamsulosin

Pharmacist-reviewed drug information from the RxWiki encyclopedia.

Overview

Flomax is a prescription medication used to treat the symptoms of enlarged prostate, known medically as benign prostatic hyperplasia (BPH). Flomax belongs to a group of drugs called alpha blockers. Unlike other BPH medicines, Flomax does not shrink the prostate. It works by relaxing the muscles in the bladder and prostate so urine can flow easily.

This medication comes as a capsule that is taken by mouth once a day. It should be taken 30 minutes after the same meal each day. Swallow Flomax capsules whole. Do not crush, chew, or open Flomax capsules.

Common side effects of Flomax include runny nose, dizziness, and decreased semen amounts.

What is it used for?

Flomax is a prescription medication used to treat the symptoms of enlarged prostate, known medically as benign prostatic hyperplasia (BPH).

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

How to take it

Take Flomax exactly as prescribed by your doctor. Follow the directions on your prescription label carefully.

For the treatment of the signs and symptoms of BPH (benign prostatic hyperplasia) the recommended dose of Flomax is 0.4 mg once a day. The dose may be increased to 0.8 mg once a day (2 capsules). Your doctor will determine the best dose for you.

Warnings

Serious side effects have occurred including:

  • Decreased blood pressure when changing positions. Flomax capsules may cause a sudden drop in blood pressure upon standing, especially after the first dose or when changing doses. 
    Symptoms may include:
    • fainting
    • dizziness
    • lightheadedness

Change positions slowly from lying down to sitting up or from a sitting to a standing position until you learn how you react to Flomax capsules. If you begin to feel dizzy, sit or lie down until you feel better. If the symptoms are severe or do not improve, call your doctor.

  • Allergic reactions. Make your doctor aware of any allergic reactions you may experience while taking Flomax.
    Allergic reactions may include:
    • rash
    • itching
    • hives
  • Rare and more serious allergic reactions may also occur. Get medical help right away if you have any of the following  reactions:
    • swelling of face, tongue, or throat
    • difficulty breathing
    • blistering of the skin
  • A painful erection that will not go away. Flomax capsules can cause a painful erection (priapism), which cannot be relieved by having sex. If this happens, get medical help right away. If priapism is not treated, you may not be able to get an erection in the future.
  • Eye problems during cataract surgery. During cataract surgery, a condition called intraoperative floppy iris syndrome (IFIS) can happen if you take or have taken Flomax capsules. If you need to have cataract surgery, be sure to tell your surgeon if you take or have taken Flomax  capsules.
  • Flomax may make you dizzy or drowsy. Do not drive a car or operate machinery until you know how this medicine affects you.

Side effects

Serious side effects can occur. See "Drug Precautions" section.

Common side effects of Flomax may include:

  • headache
  • dizziness
  • runny nose
  • abnormal ejaculation
  • general weakness
  • back pain
  • diarrhea
  • upper respiratory infection
  • chest pain
  • cough
  • sleepiness
  • nausea
  • insomnia
  • decreased libido
  • tooth disorder
  • blurred vision

These are not all the possible side effects with Flomax. Tell your doctor if you have any side effect that bothers you or that does not go away.

Call your doctor for medical advice about side effects. 

Drug interactions

Tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements. Especially tell your doctor if you are taking:

  • alfuzosin (Uroxatral)
  • doxazosin (Cardura)
  • prazosin (Minipress)
  • terazosin (Hytrin)
  • warfarin (Coumadin, Jantoven)
  • cimetidine (Tagamet)
  • sildenafil (Viagra)
  • tadalafil (Cialis)
  • vardenafil (Levitra)

This is not a complete list of Flomax drug interactions. Ask your doctor or pharmacist for more information.

Pregnancy

Tell your doctor if you are pregnant or plan to become pregnant.

The FDA categorizes medications based on safety for use during pregnancy. Five categories - A, B, C, D, and X, are used to classify the possible risks to an unborn baby when a medication is taken during pregnancy.

This medication falls into category B. It is not known if Flomax will harm your unborn baby. This medication should not be taken during pregnancy. Tell your doctor if you become pregnant while taking Flomax.

Breastfeeding

Tell your doctor if you are breastfeeding or planning to breastfeed. It is not known if Flomax will harm your nursing baby.

Quick facts

Flomax should be taken 30 minutes after the same meal each day. Swallow Flomax capsules whole. Do not crush, chew, or open Flomax capsules.

Flomax can cause a decrease in semen amounts.

Flomax capsules can cause a painful erection (priapism), which cannot be relieved by having sex. If this happens, get medical help right away.

Grapefruit and grapefruit juice may interact with Flomax and lead to potentially dangerous effects. Discuss the use of grapefruit products with your doctor.

All information on this site is provided “as-is” for informational purposes only and is not a substitute for medical advice or treatment. You should consult with a medical professional if you have any questions about your health.