Generic Name: tamsulosin (tam soo LOE sin)
Brand Name: Flomax
Medically reviewed by Sophia Entringer, PharmD. Last updated on Dec 28, 2020.
What is tamsulosin?
Tamsulosin (Flomax) is an alpha-blocker that relaxes the muscles in the prostate and bladder neck, making it easier to urinate.
Tamsulosin is used to improve urination in men with benign prostatic hyperplasia (enlarged prostate).
Tamsulosin is not FDA approved for use in women or children.
You should not use this medication 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).
Tamsulosin 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 this medicine 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 tamsulosin before surgery unless your surgeon tells you to.
There are many other drugs that can interact with this medicine. 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 tamsulosin if you are allergic to it. Do not take tamsulosin together with similar medicines such as alfuzosin (Uroxatral), doxazosin (Cardura), prazosin (Minipress), silodosin (Rapaflo), or terazosin (Hytrin).
To make sure tamsulosin 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.
Tamsulosin can affect your pupils during cataract surgery. Tell your eye surgeon ahead of time that you are using this medicine. Do not stop using tamsulosin before surgery unless your surgeon tells you to.
Although this medicine is not for use in women, tamsulosin 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.
This medicine is not approved for use by anyone younger than 18 years old.
How should I take tamsulosin?
Take tamsulosin exactly as it was prescribed for you. 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.
Tamsulosin 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 a capsule. Swallow the capsule whole.
Tamsulosin 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 tamsulosin.
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 tamsulosin 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.
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
-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
Tamsulosin 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 tamsulosin.
Tamsulosin side effects
Get emergency medical help if you have signs of an allergic reaction to tamsulosin: 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 tamsulosin side effects may include:
low blood pressure;
dizziness, drowsiness, weakness;
headache, chest pain;
abnormal ejaculation, decreased amount of semen;
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 tamsulosin?
Tell your doctor about all medicines you use, and those you start or stop using during your treatment with, 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.
More about tamsulosin
- Side Effects
- During Pregnancy
- Dosage Information
- Patient Tips
- Drug Images
- Drug Interactions
- Compare Alternatives
- Support Group
- Pricing & Coupons
- En Español
- 422 Reviews
- Drug class: antiadrenergic agents, peripherally acting
- Other brands
Related treatment guides
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use tamsulosin only for the indication prescribed.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
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