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Nov 11, 2020
4 min read

Tamsulosin side effects: things to consider

Tamsulosin helps relax the muscles of the prostate and bladder. This can allow the urethra to expand and improve the flow of urine, alleviating urinary symptoms caused by an enlarged prostate.


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.

If you’ve been prescribed tamsulosin (brand name Flomax) for benign prostatic hyperplasia (BPH), you might be wondering about potential side effects.

Although studies show that tamsulosin is a safe and effective medication, all drugs can have the potential for adverse effects. Talk to your healthcare professional if you would like more drug information, but here some of the side effects to be aware of when taking tamsulosin.

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What is tamsulosin?

Tamsulosin (brand name Flomax) is part of a class of medications known as alpha-blockers (α-blockers). It is FDA-approved to treat benign prostatic hyperplasia (BPH), also known as an enlarged prostate. This is a common condition that affects about half of all men between the ages of 51 and 60 and over 70% of men older than 60 (AUA-a, 2020; Narayan, 2005).

The prostate gland is located at the bladder’s base and surrounds the ureter, the tube that carries urine from the bladder out of the body via the penis. As your prostate gets larger, it can put pressure on the urethra, leading to lower urinary tract symptoms (LUTS). A classic symptom of BPH is needing to pee more often, especially at night. 

Other symptoms of BPH include difficulty starting urination, weak urine flow, straining when urinating, and starting/stopping frequently during urination (AUA-a, 2020). Tamsulosin helps relax the muscles of the prostate and bladder. This can allow the urethra to expand and improve the flow of urine, alleviating urinary symptoms caused by an enlarged prostate (DailyMed, 2015). 

Other examples of alpha blockers include prazosin (brand name Minipress), silodosin (brand name Rapaflo), alfuzosin (brand name Uroxatral), terazosin (brand name Hytrin), and doxazosin (brand name Cardura).

Tamsulosin side effects

Common side effects of tamsulosin include (DailyMed, 2015):

  • Dizziness or lightheadedness
  • Headache
  • Runny nose, stuffy nose, or other “common cold” symptoms
  • Abnormal ejaculation, such as ejaculation failure
  • Drowsiness
  • Diarrhea
  • Intraoperative floppy iris syndrome, something that can occur during cataract surgery or glaucoma surgery 

Serious side effects of tamsulosin can include (UpToDate, n.d.):

  • Chest pain (angina)
  • Low blood pressure or fainting (syncope), especially when standing from a sitting position (also known as orthostatic hypotension)
  • Priapism, or a painful erection that lasts more than four hours
  • A severe allergic reaction with skin rash, swelling, and trouble breathing; if you have a history of an allergy to sulfonamide (“sulfa”) drugs, you may also have an allergic reaction to tamsulosin 

This is not a comprehensive list. Seek medical advice from your healthcare provider or pharmacist for more information about potential tamsulosin side effects. 

Lastly, tamsulosin has potential drug interactions with several different medicines, like phosphodiesterase-5 (PDE5) inhibitors used to treat erectile dysfunction) and drugs that block the liver enzymes needed to break down tamsulosin. Let your healthcare professional know if you are taking any other medications, whether over-the-counter or prescription drugs. 

Tamsulosin side effects in elderly people

In the last few years, there has been some controversy about whether tamsulosin increases the risk of dementia in the elderly.

A 2018 study published in the journal Pharmacoepidemiology and Drug Safety examined Medicare data about men taking tamsulosin over a period of six years (2006-2012). The researchers found those men had a “significantly higher” risk of developing dementia than men who didn’t take the drug (Duan, 2018).

However, a 2019 study published in the Journal of Urology pointed out several limitations with the Duan, et al. study. Using records from the National Health Insurance Database, South Korean researchers looked for a connection between α-blocker use and dementia in the adult Korean population with BPH between 2011 and 2017—they didn’t find one. The authors concluded that benign prostatic hyperplasia medication is not associated with a risk of dementia (Tae, 2019). It does not seem that tamsulosin definitively increases the risk of dementia in the elderly, but more research is needed. 

Tamsulosin side effects long term

A 2005 study examined the long-term safety and effectiveness of tamsulosin, looking at a group of men who had been taking tamsulosin for six years. The researchers found that some of the most common adverse effects included infection, accidental injury, runny nose, pain, and sore throat; other reported side effects included abnormal ejaculation, syncope, and orthostatic hypotension (Narayan, 2005).

Interestingly, the side effects declined over the six-year period, with the highest levels occurring in the first two years of treatment. In fact, less than 5% of men reported these adverse effects after the first two years of treatment (Narayan, 2005).  

In summary, people taking tamsulosin to treat BPH urinary symptoms continued to have safe and well-tolerated relief of their symptoms for up to six years.  

Flomax side effects after stopping

If you stop taking tamsulosin (brand name Flomax) for a few days, talk with a healthcare provider before starting again. Some people develop low blood pressure when they resume taking tamsulosin. Your provider may have you restart at the lowest dose to prevent side effects (UpToDate, n.d.).


  1. American Urology Association (AUA-a). (2020). Urology Care Foundation: What is benign prostatic hyperplasia? Retrieved on Sep. 8, 2020 from
  2. American Urology Association (AUA-b). (2020). Urology Care Foundation: What are kidney stones? Retrieved on Sep. 8, 2020 from 
  3. DailyMed. (2015). Tamsulosin hydrochloride capsule. Retrieved on Sep. 8, 2020 from   
  4. Duan, Y., Grady, J. J., Albertsen, P. C., & Helen Wu, Z. (2018). Tamsulosin and the risk of dementia in older men with benign prostatic hyperplasia. Pharmacoepidemiology and Drug Safety, 27(3), 340–348. Retrieved from Retrieved from 
  5. Narayan, P., & Tunuguntla, H. S. (2005). Long-term efficacy and safety of tamsulosin for benign prostatic hyperplasia. Reviews in Urology, 7 Suppl 4(Suppl 4), S42–S48. Retrieved from
  6. Tae, B., Bum Sik Tae Department of Urology, Jeon, B., Byeong Jo Jeon Department of Urology, Choi, H., Hoon Choi Department of Urology, et al. (2019). α-Blocker and Risk of Dementia in Patients with Benign Prostatic Hyperplasia: A Nationwide Population Based Study Using the National Health Insurance Service Database. Retrieved from
  7. UpToDate. (n.d.). Tamsulosin: Drug information. Retrieved on Sep. 8, 2020 from