Prostate Medication

5 Alpha-Reductase Inhibitors: BPH Treatment

Benign prostatic hyperplasia (BPH) is a condition that affects a significant number of men.

The symptoms can be uncomfortable, making it difficult to urinate normally, as well as causing sexual dysfunction.

The risk for benign prostatic hyperplasia significantly increases with age.

By the age of 40, only 8% of men will experience signs that are associated with this condition1.

Benign prostatic hyperplasia affects the prostate gland. As the condition develops, the prostate gland of the patient becomes enlarged.

This can affect the functioning of the urinary tract and bladder. The result may be urinary tract symptoms, including urinary retention, and erectile dysfunction.

What are 5-Alpha Reductase Inhibitors?

5-Alpha Reductase Inhibitors is a term used to describe a family of pharmaceutical drugs, often prescribed to men diagnosed with benign prostatic hyperplasia.

These drugs target specific chemicals in the patient’s body to potentially reduce the size of the prostate. It should, however, be noted that not all of these drugs will effectively help to treat the enlarged prostate.

Some of these drugs, instead only work to assist in reducing the severity of the symptoms.

Different types of 5-Alpha Reductase Inhibitors have been developed in the last few years2.

Male patients are advised to gain more insight and select the drug type that would yield the best results for their specific condition.

The two main options that male patients may be provided with when using a 5-Alpha Reductase Inhibitor include3:

  • Dutasteride, most commonly sold under the brand name Avodart.

  • Finasteride marketed as either Proscar or Propecia.

How do 5 Alpha Reductase Inhibitors work?

Men who are considering the use of 5-Alpha Reductase Inhibitors should know about the options available. They should also have an understanding of how these drugs work as well.

The male body contains a specific enzyme that is called 5-alpha-reductase. This enzyme helps the body convert the testosterone into a different hormone, known as dihydrotestosterone (DHT). Both of these hormones play essential roles in the male body.

Medications like Finasteride and Dutasteride contain chemicals that act against the function of the 5-alpha-reductase enzyme.

When the function of this enzyme is inhibited, it means less testosterone in the male body will be converted into dihydrotestosterone.

This means there will be more testosterone hormones in the male patient’s body. Meanwhile, the amount of dihydrotestosterone circulating will start to decline with the continued use of the 5-Alpha reductase inhibitor.

Dihydrotestosterone might be useful for specific functions in the body. Still, it is essential to note that this particular hormone may contribute to two common issues in the male population.

The two conditions commonly associated with elevated DHT levels in the male body include:

In addition to these risk factors, it is also important to take note that a high level of DHT might increase the risk of prostate cancer.

Thus, the use of a 5-Alpha reductase inhibitor could also act as a means of prostate cancer prevention among men who are at an elevated risk for prostate cancer.

Types of 5 Alpha Reductase Enzymes

It is vital to take note that there are two types of 5-alpha-reductase enzymes present in the human body. Not all of the pharmaceutical drugs used in the treatment of benign prostatic hyperplasia will inhibit the functioning of both enzyme types.

The two forms of these enzymes include:

  • 5-alpha-reductase enzyme type 1

  • 5-alpha-reductase enzyme type 2

Dutasteride is a pharmaceutical drug known to interact with both of these enzymes. Finasteride, on the other hand, only interact with the 5-alpha-reductase enzyme type 1.

Due to the impact the drug has on both of these enzyme types, clinical trials have not provided enough evidence to prove this as a more effective way of reducing the conversion of testosterone to dihydrotestosterone, compared to Finasteride.

It is important also to take note that Dutasteride is sometimes combined with another drug, known as Tamsulosin. This drug is sold under the brand name Jalyn.

Tamsulosin is classified as an Alpha-Blocker and helps to assist in causing a relaxing effect in specific muscles. The muscles that are relaxed include those found at the neck of the bladder and the prostate’s muscles.

A drug like Jalyn will usually be offered to a man who experiences more noticeable symptoms with their prostate gland and urinary tract. The relaxation of the prostate gland and the bladder neck muscles might help to alleviate these symptoms at a more significant level.

Urination may improve faster and more effectively when using a drug that combines both a 5-Alpha reductase inhibitor and alpha-blockers.

Tamsulosin is sometimes given to the male patient as a separate drug. The drug does come with its range of side-effects that male patients do need to be aware of.

Flomax is not only used for male patients with benign prostatic hyperplasia. There are cases where Flomax is prescribed for women who experience urinary tract symptoms.

Are they effective in treating BPH?

Apart from understanding how these drugs work, men should know if they are effective treatment options for benign prostatic hyperplasia.

Fortunately, several studies have been conducted in the past to provide men an overview of how effective the use of 5-alpha reductase inhibitors is.

We will consider a few of these studies to provide a more accurate overview of what male patients should expect if they decide to take advantage of a drug like Finasteride or Dutasteride.

The first study4 we want to look at here was published in the Asian Journal of Urology. The study was conducted by researchers at the Washington University School of Medicine. The idea was to test the efficacy of both 5-alpha reductase inhibitors that are currently available.

Several previous studies were included in the compilation of this paper. The researchers concluded that the use of 5-alpha reductase inhibitors seemed to produce an effective reduction in serum DHT levels among men who have been diagnosed with benign prostatic hyperplasia.

This is the primary goal of the medication, which does mean the use of a 5-alpha reductase inhibitor may yield effective results.

The researchers further noted that the use of these drugs alone already yields effective results when it comes to reducing levels of DHT in the male body.

Still, there do seem to be cases where combining these medicines with other types of drugs used in the treatment of BPH may offer better results.

Another study5, published by researchers at the Southern Illinois University School of Medicine, looked at how the efficacy of a 5-alpha reductase inhibitor would compare to the results provided by other treatment options.

The effects of 5-alpha reductase inhibitors were compared to the efficacy of alpha1-adrenergic antagonists.

Researchers describe 5-alpha reductase inhibitors as a highly effective option for the treatment of benign prostatic hyperplasia, especially when compared to the efficacy offered by alternative options.

Specifically, the researchers noted that a 5-alpha reductase inhibitor could effectively reduce the prostate volume in patients with BPH. Peak urinary flow increased, and urinary symptoms improved.

Side effects of 5-Alpha Reductase Inhibitors

There are certain side-effects associated with the use of 5-alpha reductase inhibitors that patients do need to be aware of. These side-effects can be unpleasant.

The pros and cons of using these drugs should be weighed before the patient decides to utilize this type of medicine.

The following side-effects can occur in some patients who use the drug6:

  • There may be a decrease in the patient’s sex drive.

  • Retrograde ejaculation has been noted in some patients.

  • The patient may also note a reduction in their erectile function. This can cause symptoms associated with erectile dysfunction.

Natural Treatment for BPH

The side-effects that may occur when a person uses a 5-alpha reductase inhibitor may be unpleasant and cause the patient concern.

In such a case, it is important to take note that certain natural remedies have shown potential as therapies for use in patients with BPH.

When it comes to looking for a natural remedy to treat the enlarged prostate, research must be first conducted on the specific ingredients that have been clinically proven to yield effective results.

Some of the natural remedies that have shown potential at treating enlarged prostate and the additional symptoms related to the urinary tract include:

  • Saw Palmetto: One of the most popular natural remedies for enlarged prostate would be Saw Palmetto extract. This medicine is made from the fruit that grows on a palm tree. There are chemicals in the plant that may reduce inflammation and also block the specific hormones that are linked to the condition.

  • Pygeum: Pygeum extract may also help to assist in improving the urinary tract symptoms. Specifically, an improvement in urine flow and bladder emptying may be experienced.

  • Beta-Sitosterol: Another popular natural remedy would be beta-sitosterol. This is a combination of plant-based materials that could assist in improving urine flow, as well as reducing urinary symptoms.


The use of 5-Alpha Reductase Inhibitors has been proven effective in the treatment of benign prostatic hyperplasia. Men with this condition have to take note of the adverse events that may occur when they use these drugs.

Alternative treatment options have been identified for patients with BPH, including the use of certain herbal medicines that may help to improve symptoms and reduce the prostate size when an enlargement has developed.


  1. Asian Journal of Urology. (2017). Epidemiology of clinical benign prostatic hyperplasia. [online] Available at:
  2.  Food and Drug Administration (FDA). 5-Alpha Reductase Inhibitor Information. [online] Available at:
  3.  WebMD. What are the two main 5-alpha reductase inhibitors (5-ARIs) for benign prostatic hyperplasia (BPH)?. [online] Available at:
  4. Asian Journal of Urology. (2018). The use of 5-alpha reductase inhibitors in the treatment of benign prostatic hyperplasia. [online] Available at:
  5. Current Pharmaceutical Design. (2006). Inhibitors of 5alpha-reductase in the treatment of benign prostatic hyperplasia. [online] Available at:
  6. WebMD. What are the side effects of 5-alpha reductase inhibitors (5-ARIs) used to treat benign prostatic hyperplasia (BPH)? [online] Available at:

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