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Flomax

Generic name: tamsulosintam-soo-LOE-sin ]
Drug class: Alpha-adrenoreceptor antagonists

Medically reviewed by Drugs.com. Last updated on Jun 14, 2022.

What is Flomax?

Flomax is an alpha-blocker that relaxes the muscles in the prostate and bladder neck, making it easier to urinate.

Flomax is used to improve urination in men with benign prostatic hyperplasia (enlarged prostate).

Flomax is not approved for use in women or children.

Warnings

You should not use Flomax if you are allergic to tamsulosin. Do not take tamsulosin with other similar medicines such as alfuzosin (Uroxatral), doxazosin (Cardura), prazosin (Minipress), silodosin (Rapaflo), or terazosin (Hytrin).

Flomax may cause dizziness or fainting, especially when you first start taking it or when you start taking it again. Be careful if you drive or do anything that requires you to be alert. Avoid standing for long periods of time or becoming overheated during exercise and in hot weather. Avoid getting up too fast from a sitting or lying position, or you may feel dizzy.

If you stop taking Flomax for any reason, call your doctor before you start taking it again. You may need a dose adjustment.

Tamsulosin can affect your pupils during cataract surgery. Tell your eye surgeon ahead of time that you are using this medication. Do not stop using Flomax before surgery unless your surgeon tells you to.

There are many other drugs that can interact with tamsulosin. Tell your doctor about all medications you use.

Follow all directions on your medicine label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.

Before taking this medicine

You should not use Flomax if you are allergic to tamsulosin. Do not take this medicine together with similar medicines such as alfuzosin (Uroxatral), doxazosin (Cardura), prazosin (Minipress), silodosin (Rapaflo), or terazosin (Hytrin).

To make sure Flomax is safe for you, tell your doctor if you have:

  • liver or kidney disease;

  • a history of prostate cancer;

  • low blood pressure; or

  • an allergy to sulfa drugs.

Flomax can affect your pupils during cataract surgery. Tell your eye surgeon ahead of time that you are using this medicine. Do not stop using Flomax before surgery unless your surgeon tells you to.

Although this medicine is not for use in women, Flomax is not expected to harm an unborn baby. If you are a woman using this medication, tell your doctor if you are pregnant or breast-feeding.

Flomax is not approved for use by anyone younger than 18 years old.

How should I take Flomax?

Take Flomax exactly as prescribed by your doctor. Follow all directions on your prescription label. Your doctor may occasionally change your dose to make sure you get the best results. Do not take this medicine in larger or smaller amounts or for longer than recommended.

Flomax is usually taken once a day, approximately 30 minutes after a meal. Try to take this medication at the same time each day.

Do not crush, chew, or open the capsule. Swallow the capsule whole.

Flomax lowers blood pressure and may cause dizziness or fainting, especially when you first start taking it, or when you start taking it again. Call your doctor if you have severe dizziness or feel like you might pass out.

Some things can cause your blood pressure to get too low. This includes vomiting, diarrhea, heavy sweating, heart disease, dialysis, a low-salt diet, or taking diuretics (water pills). Tell your doctor if you have a prolonged illness that causes diarrhea or vomiting.

Your blood pressure will need to be checked often. You will also need to be checked for prostate cancer before and during treatment with Flomax.

You may feel very dizzy when you first wake up. Be careful when standing or sitting up from a lying position.

If you stop taking Flomax for any reason, call your doctor before you start taking it again. You may need a dose adjustment.

Store at room temperature away from moisture and heat.

Read all patient information, medication guides, and instruction sheets provided to you. Ask your doctor or pharmacist if you have any questions.

Dosing information

Usual Adult Dose for Benign Prostatic Hyperplasia:

Initial Dose: 0.4 mg orally once a day
Maximum Dose: 0.8 mg orally once a day

Comments:
-If use is discontinued or interrupted for several days at either the 0.4 mg or 0.8 mg dose, treatment should be initiated again with the 0.4 mg once a day dose.

Use: Treatment of the signs and symptoms of benign prostatic hyperplasia (BPH)

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

If you miss your doses for several days in a row, contact your doctor before restarting the medication.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What to avoid

Flomax may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert. Avoid getting up too fast from a sitting or lying position, or you may feel dizzy. Get up slowly and steady yourself to prevent a fall.

Dizziness or severe drowsiness can cause falls, accidents, or severe injuries.

To prevent dizziness, avoid standing for long periods of time or becoming overheated during exercise and in hot weather.

Drinking alcohol can increase certain side effects of Flomax.

Flomax side effects

Get emergency medical help if you have signs of an allergic reaction ro Flomax: hives, rash, itching; difficulty breathing; swelling of your face, lips, tongue, or throat.

Stop using this medicine and call your doctor at once if you have:

  • a light-headed feeling, like you might pass out;

  • penis erection that is painful or lasts 4 hours or longer; or

  • severe skin reaction--fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain, followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.

Common Flomax side effects may include:

  • dizziness, drowsiness, weakness;

  • nausea, diarrhea;

  • headache, chest pain;

  • abnormal ejaculation, decreased amount of semen;

  • back pain;

  • blurred vision;

  • tooth problems;

  • fever, chills, body aches, flu symptoms;

  • runny or stuffy nose, sinus pain, sore throat, cough;

  • sleep problems (insomnia); or

  • decreased interest in sex.

This is not a complete list of side effects and others may occur. Tell your doctor about any unusual or bothersome side effect. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect Flomax?

Tell your doctor about all medicines you use, and those you start or stop using during your treatment with Flomax, especially:

  • blood pressure medicine.

This list is not complete. Other drugs may interact with tamsulosin, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.

Popular FAQ

Does Flomax make you pee more?

Taking Flomax should cause you to more completely empty the bladder each time you pee. This results in fewer trips to the bathroom. Flomax decreases the symptoms of BPH, which include:

  • Starting and stopping the stream of urine
  • Dribbling after urination
  • A sudden strong need to urinate
  • Frequent urination
  • The sensation that the bladder is not empty after urination
  • Having trouble passing urine despite pushing and straining
  • Waking up at night to urinate

How quickly does Flomax work?

Flomax reaches its peak 4 to 5 hours after taking a dose on an empty stomach. The peak occurs 7 to 8 hours after taking a dose with food. It may take up to 5 days to see an effect on urine flow.

Does Flomax help with kidney stones?

Although it is not FDA-approved for this use, Flomax may be used to treat kidney stones. The American Academy of Family Physicians recommends the use of alpha blockers, such as Flomax, to treat kidney stones in some cases. It’s been shown to help:

  • Pass a stone that is larger than 5 millimeters
  • Decrease the time it takes to pass a stone
  • Reduce the need to go to the hospital

Can I stop taking Flomax after TURP?

It depends on whether or not you have symptoms of BPH after TURP (transurethral resection of the prostate). Your doctor may tell you to continue Flomax while the catheter is in place to aid with emptying your bladder. Depending on symptoms, you may need to continue taking Flomax long-term.

Does Flomax lower blood pressure?

Flomax may lower blood pressure when changing positions. This can happen when moving from a sitting position to a standing position. Flomax more specifically targets the receptors on the prostate than the receptors on blood vessels. Be sure to let your doctor know if you are taking other drugs for high blood pressure.

Do I have to take Flomax forever?

Flomax is usually taken long-term. If your doctor prescribes it and it is working for you, you will likely continue taking it forever. Your doctor will continue to monitor your symptoms of BPH. It’s important to keep all of your follow-up appointments.

Why is Flomax given at night?

Flomax should be taken at the same time each day, about 30 minutes after a meal, such as dinner.

Flomax can cause a drop in blood pressure when moving from sitting to standing. Symptoms may include feeling dizzy, lightheaded or fainting. If you have these symptoms, you may wish to take Flomax at bedtime. If Flomax doesn’t cause these problems for you, you may take it in the morning.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Flomax only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.