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Generic Flomax for enlarged prostate

yael coopermananna brooks

Reviewed by Yael Cooperman, MD, written by Anna Brooks

Last updated: May 12, 2021
6 min read


If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.

Flomax, sold under the generic name tamsulosin, is part of a drug class called alpha blockers.

Alpha is short for alpha-adrenergic receptors. Blocking these receptors causes muscles in the prostate gland and bladder to relax, allowing for a freer flow of urine (Nachawati, 2020).

Tamsulosin may be prescribed on its own or paired with another type of drug called 5-alpha reductase (5-AR) inhibitors. Examples of 5-AR inhibitors are finasteride (brand name Propecia; see Important Safety Information) for hair loss and dutasteride––another prostate medication. Tamsulosin is also available in a combined pill with dutasteride under the brand names Jalyn, Combodart, and Duodart. 



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Generic Flomax for benign prostatic hyperplasia (BPH)

BPH is a medical condition more commonly known as an enlarged prostate. Men’s prostates have two growth stages. The first occurs during puberty, and the second begins in their mid-20s and continues throughout life. 

During this second growth period, the prostate can grow in such a way that it presses against the urethra (the tube that carries urine), making it difficult to urinate. This may result in thickening of the bladder walls, which can cause even more problems (NIDDK, 2014).

The exact reason BPH happens isn’t fully understood, however, we do know the majority of men who live long enough will have it. Autopsies have shown 8% of men in their thirties showed signs of BPH compared to 50% in their fifties, and 80% in their eighties (Patel, 2014).

Despite the condition being labelled benign, that doesn’t mean it can’t cause troublesome. In BPH, benign means not malignant (an example of malignant is prostate cancer).

Symptoms of BPH

There is no cure for BPH, but its symptoms can be treated. Symptoms of BPH are also referred to as lower urinary tract symptoms (LUTS).

LUTS fall into two categories. Voiding symptoms include hesitancy, straining, or a weak stream when urinating. Storage symptoms include a sense of urgency, frequent urination, and waking up in the middle of the night to pee (Kapoor, 2012).

Not all men with BPH develop LUTS. For some, a small enlargement may go unnoticed. For others, treatment is necessary. Not all LUTS are caused by BPH, so it’s important to talk with a healthcare provider or urologist if you’re experiencing symptoms.

Other uses for tamsulosin

Tamsulosin may also be prescribed off-label to treat other related medical conditions.

One is kidney stones, which happens when stagnant urine crystallizes. Most small stones pass unnoticed, but large ones can get stuck traveling from the kidneys to the bladder. Kidney stones cause extreme pain, cramping, and bloody urine. If left untreated, stones can lead to an infection.

Researchers have found a higher percentage of patients taking tamsulosin were able to expel stones compared to those taking a placebo. In addition, those who expelled stones were able to get rid of them faster. Patients taking tamsulosin also had a lower need for painkillers while waiting for stones to pass (Al-Ansari, 2010). 

Another condition generic Flomax can help treat is prostatitis or inflammation of the prostate. Prostatitis differs from an enlarged prostate, though some symptoms overlap. Prostatitis is sometimes the result of a bacterial infection, but can have other causes. It’s usually temporary, though some men develop chronic cases. 

One condition that’s especially difficult to treat is chronic nonbacterial prostatitis (CNP), also known as chronic pelvic pain syndrome (CPPS). Like BPH, there’s cure-all but symptoms can be treated. Studies have demonstrated tamsulosin is superior to placebo at reducing pain and urinary symptoms (Nickel, 2004).

Tamsulosin may be prescribed off-label to women with LUTS. Current research implies it is particularly effective in relieving issues related to voiding (Meyer, 2012). 

Side effects of Flomax

Tamsulosin is well-tolerated by most people, with few reporting adverse effects. The most common side effects of this drug include (Medline Plus, n.d.):

  • Drowsiness
  • Insomnia
  • Weakness
  • Back pain
  • Diarrhea
  • Runny or stuffy nose
  • Pain or pressure in the face
  • Sore throat, cough, fever, chills, and other flu-like symptoms
  • Blurred vision
  • Difficulty ejaculating

A small percentage of those taking tamsulosin experience postural hypotension. Postural hypotension is a sudden drop in blood pressure when standing up from a sitting or lying down position.

It can cause dizziness, lightheadedness, or even fainting (DailyMed, n.d.). If these symptoms are severe or don’t stop on their own, reach out to a medical professional for advice.

During clinical trials, between eight and 18% of patients experienced abnormal ejaculation (DailyMed, n.d.). These numbers increased with higher doses of tamsulosin.

Abnormalities included decreased ejaculate, failure to ejaculate, and retrograde ejaculation––also known as a dry orgasm. The last is when semen is released backward into the bladder rather than exiting the body. While it isn’t dangerous, it can be a cause of infertility. 

Some side effects can be a sign of something more serious, such as an allergic reaction. Contact your healthcare provider immediately if you experience any of the following when taking tamsulosin (Medline Plus, n.d.):

  • Priapism, a painful erection that lasts for hours
  • Skin rash, itching, or hives
  • Swelling anywhere around the head, such as the face, eyes, lips, tongue, or throat
  • Swelling in the extremities, such as the arms, hands, feet, ankles, or lower legs

Overdoses are rare but do happen. Signs of an overdose may include:

  • Dizziness
  • Fainting
  • Blurry vision
  • Upset stomach
  • Headache

Generic Flomax precautions

Before taking tamsulosin, be sure to tell your healthcare provider if you have any of the following (Medline Plus, n.d.):

  • Allergies to drugs, including tamsulosin and sulfa medications
  • A history of prostate cancer
  • Liver or kidney disease

Tamsulosin is not FDA-approved for use by women, but can be prescribed off-label. Tamsulosin should not be taken by women who are pregnant, could become pregnant, or who are breastfeeding.

If you’re having any sort of surgery (including dental surgery), tell a healthcare provider or dentist beforehand that you’re taking tamsulosin.

Generic Flomax can cause a condition called intraoperative floppy iris syndrome (IFIS). All alpha blockers can cause this, however, tamsulosin appears to be the most problematic. IFIS can also lead to complications during cataract surgery.

Some research suggests the effects on the eye from tamsulosin can last for years––even after stopping treatment (Gani, 2012). If you’re having eye surgery, tell your ophthalmologist if you are currently or have ever taken tamsulosin.

Drug interactions

Always tell your healthcare provider about any prescription drugs or over-the-counter medications you’re taking, including vitamins, supplements, and herbal products. Be sure to mention any of the following (Medline Plus, n.d.): 

Your prescriber may wish to monitor you for specific side effects, alter your dose, or prescribe a different treatment if you’re taking any of the above medications.

Dosage, storage, and cost

Generic tamsulosin is inexpensive, with the average cost of $10–$17 for a 30-day supply if not covered by insurance (GoodRx, n.d.).

Tamsulosin is typically prescribed in 0.4 mg daily doses. For patients not responding, the dose may be increased up to 0.8 mg daily (DailyMed, n.d.).

Tamsulosin should be stored at room temperature, away from heat and moisture. Do not keep tamsulosin in the bathroom. Keep tamsulosin and all drugs out of sight and reach of children (Medline Plus, n.d.


  1. Al-Ansari, A., Al-Naimi, A., Alobaidy, A., Assadiq, K., Azmi, M. D., & Shokeir, A. A. (2010). Efficacy of tamsulosin in the management of lower ureteral stones: A randomized double-blind placebo-controlled study of 100 patients. Urology, 75(1), 4–7.
  2. DailyMed (n.d.) FLOMAX- tamsulosin hydrochloride capsule Retrieved 11 November, 2020 from
  3. Gani, J., Perlis, N., & Radomski, S. B. (2012). Urologic medications and ophthalmologic side effects: A review. Canadian Urological Association Journal = Journal De l’Association Des Urologues Du Canada, 6(1), 53–58.
  4. GoodRX (n.d.) Tamsulosin Generic Flomax. Generated interactively: Retrieved 1 November, 2020 from
  5. Kapoor, A. (2012). Benign prostatic hyperplasia (Bph) management in the primary care setting. The Canadian Journal of Urology, 19 Suppl 1, 10–17. Retrieved from
  6. MedlinePlus (n.d.). Tamsulosin. Retrieved 20 November, 2020, from
  7. Meyer, L. E., & Brown, J. N. (2012). Tamsulosin for voiding dysfunction in women. International Urology and Nephrology, 44(6), 1649–1656.
  8. Nachawati D, Patel J. Alpha Blockers. [Updated 2020 Aug 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Retrieved from:
  9. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). (2014). Prostate enlargement (benign prostatic hyperplasia). Retrieved Dec. 6, 2020 from
  10. Nickel, J. C., Narayan, P., McKAY, J., & Doyle, C. (2004). Treatment of chronic prostatitis/chronic pelvic pain syndrome with tamsulosin: A randomized double blind trial. Journal of Urology, 171(4), 1594–1597.
  11. Patel, N. D., & Parsons, J. K. (2014). Epidemiology and etiology of benign prostatic hyperplasia and bladder outlet obstruction. Indian Journal of Urology: IJU: Journal of the Urological Society of India, 30(2), 170–176.

Yael Cooperman is a physician and works as a Senior Manager, Medical Content & Education at Ro.