How does this medication work? What will it do for me?

Tamsulosin belongs to a group of medications known as alpha 1A receptor antagonists. It is used to treat symptoms of enlarged prostate (benign prostatic hyperplasia [BPH]).

As the prostate gland enlarges, it can put pressure on the urethra, the tube that carries urine away from the bladder to be expelled. This causes a weak urine stream or a feeling of not being able to empty the bladder completely. Tamsulosin helps to relax the muscles in the prostate and the opening of the bladder. This helps the stream of urine to flow more freely and the bladder to be emptied completely.

Tamsulosin does not shrink the prostate gland. Therefore, although symptoms are improved with treatment, prostate surgery may still be needed some time in the future if the prostate gland continues to enlarge.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

Each hard gelatin, sustained-release capsule with an orange-coloured body and olive-coloured cap, with a black line at the top of the cap and of the body, imprinted with the code "TSL 0.4" with black ink on the cap and filled with white to off-white pellets, contains tamsulosin HCl 0.4 mg. Nonmedicinal ingredients: methacrylic acid-ethyl acrylate copolymer (polysorbate 80, sodium lauryl sulphate), microcrystalline cellulose, talc and triethylcitrate; shell: black iron oxide, FD&C Blue No. 2, gelatin, red iron oxide, titanium dioxide, and yellow iron oxide; imprinting ink: antifoam, black iron oxide, shellac glaze, and soya lecithin.

How should I use this medication?

The recommended dose for tamsulosin is 0.4 mg once daily. Depending on response, your doctor may recommend increasing the dose to 0.8 mg once daily.

The dose should be taken approximately 30 minutes after the same meal each day.

Swallow the capsules whole with a small amount of fluid. Do not crush, chew, or open the capsule.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important that this medication be taken exactly as prescribed by your doctor. If you miss a dose, skip the missed dose and continue on with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

If doses are missed for several days at either the 0.4 mg or 0.8 mg dose, therapy should be restarted at the 0.4 mg dosage.

Store this medication at room temperature and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take this medication if you:

  • are allergic to tamsulosin or any ingredients of the medication
  • are taking certain medications that are removed from the body by the liver such as:
    • clarithromycin
    • ketoconazole
    • nefazodone
    • protease inhibitors (e.g., lopinavir, ritonavir)
This medication is not intended for use by women or children.

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • abnormal ejaculation
  • constipation
  • decreased sexual drive or performance
  • diarrhea
  • dizziness or lightheadedness
  • headache
  • itching and hives
  • nausea
  • stuffy or runny nose
  • trouble sleeping
  • unusual weakness
  • vomiting

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • dizziness when rising from a lying or sitting position
  • fast, pounding heart beat
  • fainting
  • vision changes

Stop taking the medication and seek immediate medical attention if any of the following occur:

  •  priapism (painful, persistent erection of the penis that is not relieved by sexual activity)
  • signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)
  • signs of a severe skin reaction such as blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Allergy: Some people who are allergic to sulfonamide antibiotics also experience allergic reactions to tamsulosin. Before you take tamsulosin, inform your doctor about any previous adverse reactions you have had to medications, especially sulfamethoxazole. Contact your doctor at once if you experience signs of an allergic reaction such as skin rash, itching, difficulty breathing, or swelling of the face and throat.

Drowsiness/reduced alertness: Tamsulosin may cause drowsiness or dizziness, affecting your ability to drive or operate machinery. Avoid these and other hazardous tasks until you have determined how this medication affects you.

Eye surgery: People who will be undergoing cataract or glaucoma surgery should tell their doctor that they are taking tamsulosin. Your surgeon may advise you to temporarily stop taking the medication before the surgery.

Liver function: Liver disease or reduced liver function may cause this medication to build up in the body, causing side effects. If you have liver problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Orthostatic hypotension: People taking tamsulosin may experience orthostatic hypotension, which is low blood pressure upon arising. If you experience dizziness or weakness, sit or lie down until the symptoms have disappeared. Fainting is the most severe symptom of orthostatic hypotension. If you experience fainting, contact your doctor as soon as possible.

Priapism: Tamsulosin may cause priapism, which is a painful and persistent erection of the penis that is unrelieved by sexual activity. This condition can lead to damage to the penis or impotence if it is not treated quickly. If you suspect that you have these symptoms, call your doctor or go to the emergency room as soon as possible.

Prostate cancer: Prostate cancer and BPH cause many of the same symptoms. These two diseases frequently coexist. An evaluation should be done to rule out prostate cancer before tamsulosin therapy is started.

Pregnancy: Tamsulosin is not recommended for women, including pregnant women.

Breast-feeding: Tamsulosin is not recommended for women, including breast-feeding women.

Children: This medication is not recommended for children.

What other drugs could interact with this medication?

There may be an interaction between tamsulosin and any of the following:

  • abiraterone
  • alpha/beta agonists (e.g., epinephrine, norepinephrine)
  • alpha agonists (e.g., clonidine, methyldopa)
  • other alpha blockers (e.g., alfuzosin, doxazosin, prazosin)
  • amiodarone
  • aprepitant
  • "azole" antifungals (e.g., fluconazole, itraconazole, ketoconazole)
  • barbiturates (e.g., phenobarbital, pentobarbital)
  • beta-adrenergic blockers (e.g., atenolol, propranolol, sotalol)
  • boceprevir
  • bosentan
  • calcium channel blockers (e.g., amlodipine, diltiazem, nifedipine, verapamil)
  • carbamazepine
  • cimetidine
  • conivaptan
  • cyclosporine
  • deferasirox
  • desipramine
  • dexamethasone
  • grapefruit juice
  • haloperidol
  • HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., delaviridine, efavirenz, etravirine, nevirapine)
  • HIV protease inhibitors (e.g., indinavir, lopinavir, nelfinavir, ritonavir)
  • macrolide antibiotics (e.g., clarithromycin, erythromycin, telithromycin)
  • medications for erectile dysfunction (e.g., sildenafil, tadalafil, vardenafil)
  • metronidazole
  • mifepristone
  • mitotane
  • monoamine oxidase inhibitors (MAOIs; e.g., moclobemide, phenelzine, rasagiline, selegiline, tranylcypromine)
  • nefazodone
  • norfloxacin
  • oxcarbazepine
  • peginterferon Alfa-2b
  • phenytoin
  • primidone
  • rifabutin
  • rifampin
  • quinidine
  • sertraline
  • silodosin
  • simeprevir
  • St. John's wort
  • telaprevir
  • tetracycline
  • tocilizumab

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.