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.

The recommended dose for tamsulosin controlled-release tablets is 0.4 mg once daily, taken with or without food taken at the same time each day.

The tablets must be swallowed whole. Do not crush or chew the tablets.

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, take it as soon as possible and continue with your regular schedule. If you remember the day after your scheduled 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.

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

Each yellow, biconvex, oval-shaped film coated tablet, engraved with "T04" on one side and plain on the other, contains 0.4 mg of tamsulosin hydrochloride. Nonmedicinal ingredients: colloidal silicon dioxide, magnesium stearate, microcrystalline cellulose and polyethylene oxide; Opadry coating: hydroxypropyl methylcellulose, polyethylene glycol, titanium dioxide, iron oxide red, and iron oxide yellow.

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 ketoconazole

This medication is not intended for use by women or children.

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 performance
• diarrhea
• dizziness or lightheadedness
• headache
• nausea
• stuffy or runny nose
• 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 heartbeat
• fainting

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)
• severe skin rash, itching, and hives
• signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)

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.

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: During eye surgery for cataracts, people who take or have taken tamsulosin are at risk for developing a condition called Intraoperative Floppy Iris Syndrome (IFIS). This condition can lead to eye damage. If you are planning to have an operation on your eye, inform your doctor if you are taking or have taken 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.

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

• abiraterone
• aldesleukin
• aliskiren
• alpha/beta-agonists (e.g., epinephrine, norepinephrine)
• alpha-agonists (e.g., clonidine, methyldopa)
• other alpha-blockers (e.g., alfuzosin, doxazosin, prazosin, silodosin)
• amiodarone
• angiotensin converting enzyme inhibitors (ACEIs; captopril, ramipril)
• angiotensin receptor blockers (ARBs; e.g., candesartan, irbesartan, losartan)
• antipsychotics (e.g., cariprazine, chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, risperidone)
• apomorphine
• aprepitant
• "azole" antifungals (e.g., fluconazole, itraconazole, ketoconazole)
• barbiturates (e.g., butalbital, phenobarbital)
• beta-adrenergic blockers (e.g., atenolol, carvedilol, propranolol, sotalol)
• brimonidine
• bromocriptine
• bupropion
• calcium channel blockers (e.g., amlodipine, diltiazem, nifedipine, verapamil)
• cimetidine
• cinacalcet
• clomipramine
• cobicistat
• conivaptan
• darifenacin
• decongestant cold medications (e.g., ephedrine, phenylephrine, pseudoephedrine)
• decongestant eye drops and nasal sprays (e.g., naphazoline, oxymetazoline, xylometazoline)
• dexmedetomidine
• diazoxide
• dinutuximab
• diuretics (water pills; e.g., furosemide, hydrochlorothiazide, triamterene)
• dronedarone
• duloxetine
• eplerenone
• fluoxetine
• general anesthetics (medications used to put people to sleep before surgery)
• grapefruit juice
• guanfacine
• HIV protease inhibitors (e.g., atazanavir, darunavir, lopinavir, ritonavir)
• hydralazine
• imipramine
• letermovir
• levodopa
• macrolide antibiotics (e.g., clarithromycin, erythromycin)
• mifepristone
• mirabegron
• monoamine oxidase inhibitors (MAOIs; e.g., phenelzine, rasagiline, selegiline, tranylcypromine)
• morphine
• nirmatrelvir
• nitrates (e.g., nitroglycerin, isosorbide dinitrate, isosorbide mononitrate)
• obinutuzumab
• paroxetine
• peginterferon alfa-2b
• pentoxifylline
• phosphodiesterase 5 inhibitors (e.g., sildenafil, tadalafil, vardenafil)
• pramipexole
• primidone
• certain protein kinase inhibitors (e.g., bortezomib, ceritinib, crizotinib, idelalisib, imatinib, nilotinib, palbociclib, ribociclib)
• riociguat
• ropinirole
• rotigotine
• sacubitril
• spironolactone
• terbinafine
• tizanidine
• tretinoin

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.