By Medically reviewed by Hello Doktor Medical Panel


What is Flomax® (tamsulosin) used for?

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.

How should I take Flomax® (tamsulosin)?

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.

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

How do I store Flomax® (tamsulosin)?

Flomax® is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store Flomax® in the bathroom or the freezer. There may be different brands of Flomax® that may have different storage needs. It is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush Flomax® down the toilet or pour them into a drain unless instructed to do so. It is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Precautions & warnings

What should I know before using Flomax® (tamsulosin)?

Before using this drug, tell your doctor if:

  • You are pregnant or breastfeeding. This is because, while you are expecting or feeding a baby, you should only take medicines on the recommendation of a doctor.
  • You are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, such as herbal and complementary medicines.
  • You have allergy with any of active or inactive ingredients of Flomax® or other medications.
  • You have any other illnesses, disorders, or medical conditions.

Do not take this medicine together with similar medicines such as alfuzosin (Uroxatral), doxazosin (Cardura), prazosin (Minipress), silodosin (Rapaflo), or terazosin (Hytrin).

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.

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

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

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®.

Is it safe during pregnancy or breastfeeding?

There are no adequate studies in women for determining risk when using Flomax® during pregnancy or while breastfeeding. Please always consult with your doctor to weigh the potential benefits and risks before taking Flomax®. Flomax® is pregnancy risk category B, according to the US Food and Drug Administration (FDA).

FDA pregnancy risk category reference below:

  • A=No risk
  • B=No risk in some studies
  • C=There may be some risk
  • D=Positive evidence of risk
  • X=Contraindicated
  • N=Unknown

Side effects

What side effects can occur from Flomax® (tamsulosin)?

Common 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)
  • Decreased interest in sex

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
  • 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

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

Not everyone experiences these side effects. There may be some side effects not listed above. If you have any concerns about a side-effect, please consult your doctor or pharmacist.


What drugs may interact with Flomax® (tamsulosin)?

Flomax® may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs, and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval.

Product that may interact with this drug is blood pressure medicine.

Does food or alcohol interact with Flomax® (tamsulosin)?

Flomax® may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with Flomax® (tamsulosin)?

Flomax® may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works. It is important to always let your doctor and pharmacist know all the health conditions you currently have.

Health conditions that may interact with this drug are:

  • Liver or kidney disease
  • A history of prostate cancer
  • Low blood pressure
  • An allergy to sulfa drugs


The information provided is not a substitute for any medical advice. You should ALWAYS consult with your doctor or pharmacist before using Flomax® (tamsulosin).

What is the dose of Flomax® (tamsulosin) for an adult?

Usual Adult Dose for Benign Prostatic Hyperplasia:

Initial Dose: The recommended dose is 0.4 mg orally once a day.

Maximum Dose: The recommended dose is 0.8 mg orally once a day.

What is the dose of Flomax® (tamsulosin) for a child?

The dosage has not been established in pediatric patients. It may be unsafe for your child. It is always important to fully understand the safety of the drug before using. Please consult with your doctor or pharmacist for more information.

How is Flomax® (tamsulosin) available?

Flomax® is available in the following dosage forms and strengths:

  • Capsule: tamsulosin hydrochloride 0.4mg

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

What should I do if I miss a dose?

If you miss a dose of Flomax®, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.

Hello Health Group does not provide medical advice, diagnosis or treatment.

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Review Date: July 19, 2017 | Last Modified: December 19, 2019

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