Finasteride vs. Flomax: Comparison of Effectiveness

Published February 8th, 2021 by Erik Rivera
Fact Checked by
Camille Freking
Medically Reviewed:
Gerardo Sison
Updated Date: Jun 23rd, 2022

As men age, they are more likely to suffer from medical conditions resulting from changing hormone levels in their bodies, including enlarged prostate.

Also known as benign prostatic hyperplasia (BPH), the condition can cause a number of uncomfortable urinary symptoms that get worse with age. 

Two popular medications that have shown significant improvements for the treatment of urinary BPH symptoms include finasteride and Flomax.

If you are considering taking either medication, you’ll be interested to read the comparison of effectiveness between the two here.

Finasteride vs. Flomax Overview

Finasteride is a generic prescription medication that is sold under the brand name Proscar.

The Food and Drug Administration (FDA) recommends finasteride be taken orally at a dose of 1 mg or 5 mg per day, depending on which condition is being treated. 

Flomax is a brand name prescription medication that is sold under the generic name tamsulosin.

The drug is taken orally once per day regardless of which medical therapy it is being used for.

Finasteride vs. Flomax Conditions Treated

Finasteride and Flomax are both used for the treatment of symptoms of benign prostatic hyperplasia, also known as enlarged prostate, in adult men.

In addition to treating symptoms of benign prostatic hyperplasia, finasteride is also used for the treatment of male pattern baldness, while Flomax may be used to treat stones in the male urinary tract. 

Benign prostatic hyperplasia

Benign prostatic hyperplasia is a common medical condition that affects men as they age.

The condition can range in severity from mild to severe, and symptoms tend to get worse with age.

However, the size of your prostate is not the determining factor in terms of the severity of your symptoms.

It is possible to have relatively minor prostate enlargement and experience severe urethral symptoms or significant prostate enlargement with only minor symptoms.

There are many urethral symptoms of BPH because the prostate is so close to the urethra. 

Urology symptoms of benign prostatic hyperplasia include:

  • Frequent need to urinate
  • Urgent need to urinate
  • Weak urine stream
  • Urinary retention
  • Urine stream that stops and starts
  • Inability to empty the bladder completely
  • Nighttime urination (nocturia)
  • Difficulty starting to urinate
  • Dribbling following urination

Male pattern baldness

Male pattern baldness is a hereditary condition that occurs in an estimated 50 million men in the United States and tends to get worse with age.

The condition is characterized by a receding hairline and thinning hair that occurs primarily on the crown of the head.

Male pattern baldness is caused by an increase in the levels of a hormone called dihydrotestosterone (DHT), which causes the hair follicles to shrink, pushing out existing hair and preventing growth of new hair.

DHT is the same hormone that causes benign prostatic hyperplasia, which is why there is some overlap in medications that treat the conditions.

Finasteride is often used in combination therapy with minoxidil and DHT-blocking shampoo with saw palmetto, caffeine, and other hair-boosting ingredients.

Urinary stones

Urinary stones occur when minerals in concentrated urine form stones through the process of crystallization.

They most commonly occur as a result of incomplete emptying of the bladder, which can occur due to benign prostatic hyperplasia or nerve damage in the vicinity of the bladder. 

However, urinary stones can also occur as a result of bladder inflammation, use of catheters, or the development of kidney stones that travel into the bladder.

Men over the age of 50 are the most likely to have bladder stones.

Symptoms associated with urinary stones include pain during urination, lower abdominal pain, difficulty urinating or interrupted urine flow, cloudy or abnormally dark-colored urine, frequent urination, and blood in the urine.

Finasteride vs. Flomax Drug Class and Treatment Mechanisms

While both finasteride and Flomax are used for the treatment of benign prostatic hyperplasia in men, the medications work differently and have different treatment mechanisms.

Finasteride works to shrink the size of the enlarged prostate, while Flomax works in other ways to relieve the symptoms associated with the condition and improve quality of life.

Flomax and finasteride belong to two different classes of prescription drugs. Flomax, belongs to a class of drugs called alpha blockers.

Alpha blockers like Flomax are commonly used for the treatment of high blood pressure and prostate problems in men, and also include the drugs doxazosin, terazosin, and alfuzosin. 

Medications in this class of drugs work by preventing the hormone norepinephrine from causing smooth muscle contractions in the walls of the smaller veins and arteries in the body.

By blocking the action of norepinephrine, the blood vessels remain relaxed and open, which helps to lower blood pressure and improve blood flow. 

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As a byproduct of this effect, other muscles in the body, such as those in the urinary tract, remain relaxed, which helps to reduce the urinary symptoms associated with benign prostatic hyperplasia.

While Flomax can relieve urinary symptoms associated with enlarged prostate, it should be noted that the medication does not work to reduce the size of the prostate.

Finasteride belongs to a class of drugs called 5-alpha reductase inhibitors, which also includes Avodart (dutasteride).

The body uses the 5-alpha reductase enzyme to convert testosterone in the body into a substance called DHT.

When DHT in the body rises, they contribute to enlargement of the prostate and hair loss in men who are genetically predisposed to male pattern baldness.

Finasteride lowers the levels of DHT in the body, causing the size of the prostate to shrink for as long as the medication is taken.

As a result, urinary symptoms associated with benign prostatic hyperplasia are typically diminished as the prostate shrinks.

Finasteride vs. Flomax Comparison of Effectiveness

Numerous studies have been conducted that compare the effectiveness of finasteride vs. Flomax. 

One study, conducted over the course of 24 weeks, found  that the two medications were equally effective in the long term treatment of urinary symptoms associated with benign prostatic hyperplasia; however, Flomax was found to be a better option for short term treatment.

The study also demonstrated that finasteride is associated with significantly more side effects and adverse events than Flomax.

Another study, conducted over the course of one year, found that Flomax resulted in greater improvements in total urinary symptoms than finasteride, with study participants treated with Flomax reporting a 37 percent reduction in symptoms while participants using finasteride reported a 31 percent reduction in symptoms.

The study also found that Flomax worked faster to improve urinary symptoms, particularly symptoms of urgency and needing to use the bathroom more frequently.

This study found that both treatments were well tolerated and had a comparable incidence of adverse events and side effects.

Finasteride vs. Flomax Side Effects

Finasteride and Flomax are both generally well tolerated by patients who use the drugs for the treatment of benign prostatic hyperplasia and suffer from lower urinary tract symptoms including decreased urinary flow, altered flow rate, and incontinence.

However, like all medications, they are associated with the risk of certain side effects.

Flomax is generally found to cause fewer and less severe side effects than Flomax, but both medications can cause reduction in sexual arousal or desire, particularly when first beginning treatment.

Regardless of whether a patient is taking Flomax or finasteride, adverse effects are most likely to occur at the beginning of treatment and disappear or diminish over the course of several days or weeks.

Clinical trials have shown that finasteride does not increase the risk of prostate cancer.

Finasteride side effects

The use of finasteride for the treatment of benign prostatic hyperplasia is associated with more side effects than the use of the medication for the treatment of male pattern baldness because of the higher dose of the drug taken for the treatment of enlarged prostate gland.

A common mild side effect of finasteride can include:

  • Sexual side effects such as ejaculation disorder or reduced ejaculate
  • Trouble getting or keeping an erection (erectile dysfunction)
  • Decreased sex drive (sexual dysfunction)
  • Breast enlargement and tenderness to the touch
  • Skin rash

While most of the side effects caused by finasteride are mild, some patients may experience severe or potentially life threatening side effects.

Patients experiencing any of the following side effects should contact a doctor right away and should contact 911 if their symptoms feel life threatening.

  • Lumps or pain in your breasts
  • Swelling of your lips, tongue, throat, or face
  • Nipple discharge
  • Depression

Flomax side effects

Like finasteride, the use of Flomax is associated with the potential for side effects, including some that could be serious or potentially life threatening.

Most patients tolerate Flomax use well and have mild side effects that diminish over time. Compared to finasteride, Flomax has fewer side effects, and those side effects are less likely to be severe. 

Common side effects associated with Flomax include:

  • Dizziness
  • Abnormal ejaculation
  • Runny nose
  • Sexual side effects, including:
    • Difficulty with ejaculation
    • Failure to ejaculate
    • Ejaculation of semen into the bladder instead of out of the body

The following side effects associated with Flomax are rare, but they are potentially life-threatening. Make sure to seek immediate medical attention or call 911 if you experience any of the following symptoms:

  • Orthostatic hypotension, or low blood pressure that occurs when you go from sitting to standing or lying down to sitting or standing. The condition may cause dizziness, fainting, or lightheadedness.
  • Serious skin reactions, including raised welts, fever, facial swelling, difficulty breathing, or Stevens-Johnson syndrome.
  • Priapism, or painful erection lasting four hours or longer that is not relieved by having sex.
  • Intraoperative floppy iris syndrome, a complication of surgery that is performed for cataracts or glaucoma in patients who are being treated with Flomax.
  • Allergic reaction, as evidenced by rash, hives, itching, difficulty breathing, or swelling of the face, throat, or tongue.


Finasteride and Flomax both offer effective long-term treatment options for urinary symptoms associated with benign prostatic hyperplasia; however, Flomax may provide better short term relief of symptoms.

Both medications are well tolerated but do have the potential to cause troublesome side effects, including sexual side effects.

If you are disruptive side effects, schedule a follow-up for medical advice from your urologist or healthcare provider. 

Both medications are sold by prescription only and are available in generic and brand name forms at your local pharmacy.

Research, Studies and Sources:

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