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Alpha Blockers vs. 5-Alpha Reductase Inhibitors

The two most common types of benign prostatic hyperplasia (BPH) or enlarged prostate medications include alpha blockers and 5-alpha reductase inhibitors (5-ARIs). If you’re living with moderate to severe BPH or have a prostate over 30cc – about as large as a ping-pong ball – your doctor may have prescribed one of these medications.1,2

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How they work

Alpha blockers and 5-ARIs work in different ways. Alpha blockers work by helping muscles around the bladder and prostate relax. This allows the free flow of urine and can help manage symptoms of BPH. 5-ARIs are a type of medication that help reduce the size of your prostate, stalling its growth and eventually causing it to shrink. This lets urine flow freely again and manages the symptoms of an enlarged prostate.3,4 

When are they prescribed?

Alpha blockers are usually the first treatment prescribed by a doctor unless the size of your prostate is quite large. Usually the medications begin to act in a few days or weeks and you should be able to see a change in your BPH symptoms. After a trial period of 4 weeks, if there’s no change, your doctor may switch your prescription and try another alpha blocker or a 5-ARI.
5-ARIs are usually prescribed to men with a larger prostate (>30cc) and can take weeks to months to show a reduction in size of the prostate. They can also be prescribed as a combination therapy with an alpha blocker. 5-ARIs are designed to shrink the prostate itself.1,5 

Common alpha blockers and 5-ARIs6-12 

You may have heard of one of these medications as a treatment to manage the symptoms of BPH: 

Alpha Blockers5-Alpha Reductase Inhibitors
Alfuzosin (Uroxatral®) Finasteride (Proscar®)
Tamsulosin (Flomax® generic) Dutasteride (Avodart®)
Silodosin (Rapaflo®)
Doxazosin (Cardura® generic)
Terazosin (Hytrin®)  


There are several considerations to bear in mind while choosing treatment with either an alpha blocker or a 5-ARI. Below is a list highlighting key benefits for each followed by some common side effects.

Alpha Blockers5-Alpha Reductase Inhibitors
Quick relief from BPH symptoms – usually in days to weeksReduces the size of the prostate (but takes three to six months to improve urine flow)
Effective in the short term (symptoms may return once medications are stopped)Effective in the long-term
 Helps potentially avoid prostate surgery


Side Effects
Dizziness, headache and fatigue (most common)
Decrease in sex drive
Erectile dysfunction, or ED (trouble getting or keeping an erection) Erectile dysfunction, or ED (trouble getting or keeping an erection)
Retrograde ejaculation: semen enters the bladder instead of releasing from the penis during ejaculation – this is more common with tamsulosin than with the other alpha blockers listed above Ejaculation disorders such as retrograde ejaculation or decreased volume of ejaculate
Dry mouth, stuffy nose and swelling of the anklesBreast disorders (painful or enlarged breasts)
Low blood pressure (rare) with certain alpha blockers such as terazosin and doxazosin 


Now that you have a better understanding of these medications, you can have a more informed discussion with your doctor about your treatment options. It’s also important to know that there are other proven and innovative treatment options for BPH. While medications can help manage symptoms of an enlarged prostate, they have to be taken consistently to work, and some don’t actually reduce the tissue causing BPH symptoms. Minimally invasive treatment options can provide lasting relief without the daily hassle of remembering to take your medication.  

A different treatment approach

Rezūm™ Water Vapor Therapy is a minimally invasive option for men 50 years or older that uses the natural energy of water vapor to shrink excess prostate tissue. Rezūm Therapy can provide long-lasting relief, and the procedure takes an average of 10 minutes.13 And with Rezūm Therapy, you can preserve your sexual function.13 
Medication is often a first-line treatment for BPH but why manage symptoms instead of treating the condition? Based on data from 947 patients, 86% of BPH patients receive Rezūm as a first-line therapy or an alternative to BPH medication.14*
Talk to your doctor about whether Rezūm Therapy is right for you.

* Data collected by or on behalf of BSC. Data on file.

Most patients report relatively minor discomfort during the Rezūm procedure. Potential risks associated with Rezūm Water Vapor Therapy include but are not limited to painful or frequent urination, blood in the urine or semen, decrease in ejaculatory volume, urinary tract infection (UTI), inability to urinate or completely empty the bladder, and urgent need to urinate. During healing, symptoms may continue or worsen. Most men require a catheter for several days post-procedure.13,15 A complete list of risk information can be found here.

Find a Doctor

Use our Doctor Finder to get in direct contact with urologists who specialize in using Rezūm Water Vapor Therapy to treat BPH. 

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  1. Lerner LB, McVary, KT, Barry MJ, et al. Management of lower urinary tract symptoms attributed to benign prostatic hyperplasia: AUA Guideline part I, initial work-up and medical management. J Urol. 2021 Oct;206(4):806-17. 
  2. What We Know About your Prostate. UT Southwestern Medical Center. Accessed May 11, 2022. 
  3. Alpha-blockers. Cleveland Clinic. Accessed April 25, 2022. 
  4. Benign Prostatic Hyperplasia (BPH). Urology Care Foundation. Accessed May 3, 2022. 
  5. Kim EH, Brockman JA, Andriole GL. The use of 5-alpha reductase inhibitors in the treatment of benign prostatic hyperplasia. Asian J Urol. 2018;5(1):28-32. 
  6. Cardura Label. U.S. Food and Drug Administration. Accessed April 25, 2022. 
  7. Hytrin Label. U.S. Food and Drug Administration. Accessed April 25, 2022. 
  8. Flomax Prescribing Information. U.S. Food and Drug Administration. Accessed April 25, 2022. 
  9. Rapaflo Prescribing Information. U.S. Food and Drug Administration. Accessed April 25, 2022. 
  10. Uroxatral Prescribing Information. U.S. Food and Drug Administration. Accessed April 25, 2022. 
  11. Proscar Tablets Patient Information. Organon Global Inc. Accessed April 26, 2022.  
  12. Avodart Consumer Medicine Information. GlaxoSmithKline plc. Accessed April 26, 2022. 
  13. McVary KT, Gittelman MC, Goldberg KA, et al. Final 5-year outcomes of the multicenter randomized sham-controlled trial of Rezūm water vapor thermal therapy for treatment of moderate-to-severe lower urinary tract symptoms secondary to benign prostatic hyperplasia. J Urol. 2021 Sep;206(3):715-24. 
  14. Data on file with Boston Scientific.  
  15. Mooney R, Goldberg K, Wong D, et al. Convective radio frequency thermal therapy for treatment of benign prostatic hyperplasia: single office experience with 255 patients over 4 years. Urol Pract. 2020 Jan;7(1):28-33. 

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