Uses

What is tamsulosin used for?

Tamsulosin is commonly used to treat benign prostatic hyperplasia (BPH), a condition where the prostate gland is enlarged but not cancerous. When the prostate gets larger than usual, it pinches the urethra. This may lead to problems with your bladder muscles and urination (peeing).

Tamsulosin is used to help reduce the following symptoms of BPH.

  • Frequent need to pee
  • Urgent need to pee
  • Waking up overnight to pee 
  • Trouble getting your flow of urine to start or stop
  • Urine stream that is weak, dribbles, or pauses
  • Feeling like your bladder is not empty after you pee

Tamsulosin may also be used for other conditions as determined by your healthcare provider.

How does tamsulosin work (mechanism of action)?

Tamsulosin is an alpha blocker. It works to relax the smooth muscles in your prostate and bladder. This makes it easier to pee and improves the flow of urine.

How is tamsulosin supplied (dosage forms)?

Tamsulosin is available as Flomax and generic tamsulosin in the following dosage forms that are taken by mouth.

  • 0.4 mg oral capsule

How should I store tamsulosin?

Store tamsulosin at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place. 

Side Effects

What are the most common side effects of tamsulosin?

The most common side effects of tamsulosin are listed below. Tell your healthcare provider if you have any of these side effects that bother you.

  • Dizziness
  • Runny nose or stuffy nose
  • Less semen than usual or other problems with ejaculation
  • Headache
  • Infection, such as colds
  • Feeling unusually weak or tired
  • Diarrhea
  • Back pain
  • Cough
  • Drowsiness
  • Trouble sleeping

There may be other side effects of tamsulosin that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of tamsulosin?

While less common, the most serious side effects of tamsulosin are described below, along with what to do if they happen.

Low Blood Pressure Upon Standing. Tamsulosin may cause a sudden drop in blood pressure upon standing up from a seated or lying position (orthostatic hypotension). This side effect is more common after the first dose of tamsulosin and after changes in dose. To help avoid injury, be careful not to get up too quickly. If you feel dizzy, sit or lie down right away until the dizziness stops, then take your time getting up again. Tell your healthcare provider if you have any of the following symptoms.

  • Dizziness, feeling lightheaded, or fainting upon standing
  • Blurred vision
  • Confusion
  • Feeling weak 

Painful, Prolonged Erection (Priapism). Tamsulosin may cause an unwanted erection that is persistent, painful, and that may occur without sexual arousal. Priapism may cause permanent damage to the penis. Stop taking tamsulosin and get emergency help right away if you have any of the following symptoms of priapism. 

  • Erection lasting for more than 4 hours 
  • Erection that is unrelated to sexual stimulation
  • Painful or tender penis

Severe Allergic Reactions. Tamsulosin may cause allergic reactions, which can be serious. Stop using tamsulosin and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Warnings & Precautions

Who should not take tamsulosin?

Allergies to Ingredients. People who are allergic to any of the following should not take tamsulosin.

  • Flomax
  • Tamsulosin
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific tamsulosin products they stock.

What should I know about tamsulosin before taking it?

Do not take tamsulosin unless it has been prescribed to you by a healthcare provider. Take it as prescribed.

Do not share tamsulosin with other people, even if they have the same condition as you. It may harm them.

Tamsulosin may cause dizziness. Do not drive or do other activities that require coordination until you know how tamsulosin affects you.

Keep tamsulosin out of the reach of children.

Do not chew, crush, or open tamsulosin capsules.

Tamsulosin is commonly used to treat benign prostatic hyperplasia (BPH), which is non-cancerous enlargement of the prostate. In some cases, BPH can occur at the same time as prostate cancer. Your healthcare provider may recommend getting tested for prostate cancer before you start tamsulosin and getting regular screenings thereafter. 

What should I tell my healthcare provider before taking tamsulosin?

Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if tamsulosin is right for you.

In particular, make sure that you discuss any of the following.

Planned Eye Surgery. Taking tamsulosin may raise the risk of eye problems during or after cataract or glaucoma surgery. Tell your healthcare provider if you are planning to have eye surgery. They may recommend that you wait until after the surgery is over to start tamsulosin.

Severe Kidney Problems. Tell your healthcare provider if you have kidney problems now or in the past. It is not known if tamsulosin is safe to take if you have severe kidney problems. Your healthcare provider may not recommend tamsulosin if your kidneys are not working as well as they should be.

Severe Liver Problems. Tell your healthcare provider if you have liver problems now or in the past. They may not prescribe tamsulosin if your liver is not working as well as it should be. It is not known if tamsulosin is safe to take if you have severe liver problems.

Low Blood Pressure. Taking tamsulosin may cause brief episodes of low blood pressure, which may result in dizziness or fainting. If you already have low blood pressure, this side effect may be more severe or more likely to occur. Tell your healthcare provider if you have problems with low blood pressure. They can determine if tamsulosin is safe for you to take.

Other Medicines and Supplements. Tamsulosin may interact with other medicines and supplements. Before taking tamsulosin, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Sulfa Allergy. While rare, some people that have a sulfa allergy may also be allergic to tamsulosin. A sulfa allergy is a rash or more serious reaction to sulfa, or sulfonamide, medicines. Examples of sulfa medicines include sulfamethoxazole, sulfadiazine silver, or sulfasalazine. Tell your healthcare provider if you have any allergies to medicines. They can help you decide if it is safe for you to take tamsulosin.

Pregnancy. It is not known if or how tamsulosin could affect pregnancy or an unborn baby. Tell your healthcare provider if you are or plan to become pregnant.

Breastfeeding. It is not known if tamsulosin passes into breast milk. Tell your healthcare provider if you are breastfeeding or plan to breastfeed.

Interactions

Does tamsulosin interact with foods or drinks?

Your healthcare provider may recommend limiting or avoiding grapefruit while taking tamsulosin. Eating grapefruit or drinking grapefruit juice can increase your risk of side effects from tamsulosin. Grapefruit and grapefruit juice may raise the blood levels of tamsulosin. 

You should take tamsulosin about 30 minutes after the same meal each day. For example, you can take tamsulosin about 30 minutes after you eat breakfast each day.

It is unknown if drinking alcohol will affect tamsulosin. The risk of side effects, such as dizziness and low blood pressure, may be increased if you drink alcohol while taking tamsulosin.

Does tamsulosin interact with other medicines (drug interactions)? 

Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. 

In particular, make sure to discuss if you are using any of the following before taking tamsulosin.

  • A medicine for high blood pressure
  • A medicine in the same drug class as tamsulosin (alpha blocker), such as doxazosin (Cardura) or prazosin (Minipress) 
  • Ketoconazole, which is a medicine used for fungal infections
  • Erythromycin (Ery-Tab and others), which is a medicine used for bacterial infections
  • Paroxetine (Paxil), which is a medicine used for depression, anxiety, or other mental health conditions
  • Terbinafine, which is a medicine used for fungal infections
  • Cimetidine (Tagamet HB), which is a medicine used for heartburn
  • Warfarin (Jantoven), which is a blood thinner medicine for blood clots
  • A type of medicine called a phosphodiesterase-5 (PDE-5) inhibitor, such as sildenafil (Viagra, Revatio, and others), tadalafil (Cialis and others), or vardenafil (Levitra, Staxyn), which are used for erectile dysfunction or pulmonary arterial hypertension

Some other medicines may alter the blood levels of tamsulosin. Tell your healthcare provider about all medicines that you take or have recently taken.

This may not be a complete list of medicines that can interact with tamsulosin. Always check with your healthcare provider.

Does Tamsulosin (Flomax) interact with other drugs you are taking?
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Overdose/Missed Dose

What should I do if I accidentally take too much tamsulosin?

If you or someone else has taken too much tamsulosin, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of tamsulosin?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses. 

If you miss tamsulosin for several days, call your healthcare provider for advice.

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