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Does Finasteride Reduce Testosterone? (Science-Based)

Tyler Sellers
Published by Tyler Sellers | Senior Coach
Last updated: August 8, 2023

Some of my male fitness clients are taking finasteride to treat benign prostatic hyperplasia (BPH) or hair loss, and recently we were discussing whether this medication impacts their testosterone levels or not.

I always strive to answer my clients’ questions with scientific evidence, so I read several randomized controlled studies and systematic reviews and discussed my notes with our medical professional to get to the bottom of this.

Here’s what you need to know about finasteride and testosterone.

Quick Summary

  • Taking finasteride does not lower testosterone levels, but blocks the conversion of testosterone to dihydrotestosterone, increasing free testosterone levels.
  • Doctors may prescribe finasteride treatment for male pattern baldness and prostate enlargement, but not prostate cancer.
  • Some side effects of finasteride include erectile dysfunction, depression, and anxiety.

Does Finasteride Lower Testosterone Levels?

Pouring a blue pill on hand

Finasteride does not lower testosterone levels because it works by decreasing serum DHT concentrations, thus increasing circulating levels of testosterone.

The next paragraph will get a bit more technical but bear with me.

The enzyme 5-alpha reductase converts testosterone to dihydrotestosterone (DHT), another androgen that plays an essential role in forming male characteristics.

As a 5-alpha reductase inhibitor, finasteride blocks the conversion of testosterone to DHT [1].

This might seem complicated, but the takeaway is that the result of the body not converting testosterone to dihydrotestosterone (DHT) is increased serum testosterone levels.

Dihydrotestosterone (DHT)

DHT is a significantly more androgenic hormone than testosterone.

One definition of androgenic states the following: “pertaining to the development of male characteristics, including body hair, the genital organs, and muscle mass” [2].

As such, DHT significantly impacts hair, muscle mass, and other male characteristics.

While it does stimulate the growth of body hair, research links high levels of DHT to the shrinkage of hair follicles on the scalp, leading to hair loss [3].

Let’s take a closer look at finasteride.

What is Finasteride?

Finasteride pills spilled on floor

Finasteride is in a class of medications known as 5-alpha reductase inhibitors and is used to treat benign prostatic hyperplasia (BPH), the enlargement of the prostate [4].

Common brand names for finasteride are Propecia and Proscar.

Besides treating BPH, it can also treat male pattern baldness, known as androgenetic alopecia.

It’s important to note that taking finasteride is approved for shrinking an enlarged prostate and treating hair loss but not for prostate cancer.

Side Effects of Finasteride

As with any medication, patients taking finasteride experience some adverse side effects [5].

They include:

  • Decreased libido
  • Erectile dysfunction (ED)
  • Decreased semen volume
  • Back pain
  • Decreased semen production
  • Diarrhea
  • Dizziness
  • Headache
  • Stomach pain
  • Breast enlargement and tenderness
  • Skin itching, rash, or redness
  • Rapid or unusual weight gain or loss
  • Bloating or swelling of the face, arms, hands, lower legs, or feet

Some patients taking finasteride continue to have side effects after stopping the medication, leading to a condition called Post-Finasteride Syndrome (PFS) and symptoms include sexual dysfunction, depression, and anxiety [6].

Warnings and Interactions

A doctor's appointment with client

Additionally, patients taking finasteride should be aware of some specific warnings and interactions [7].

The most important ones are the following:

  • It can affect the blood test (PSA levels) used to detect prostate cancer.
  • Tell your physician or pharmacist if you have a history of prostate cancer, urinary problems, or liver disease.
  • The skin absorbs this medication, so if there is a breakage in the coating, a pregnant woman should not handle it.
  • Exposing developing male infants to finasteride can cause genital abnormalities.
  • Pregnant or breastfeeding women should avoid it.
  • Studies continue to try and determine a link between finasteride and male breast cancer.

How to Boost Testosterone

Person flexing bicep muscles

Low testosterone can affect men physically and mentally by impacting erectile function, body fat, hair growth, muscle mass, depression, anxiety, and cognitive function [8].

Seeking advice from a medical professional is always advised, and they may decide your testosterone levels require hormone replacement therapy which comes in various forms, including:

  • Skin patches
  • Gels
  • Nasal sprays
  • Injections
  • Tablets
  • Implantable pellets

However, always keep in mind that unless your condition requires medical intervention, boosting testosterone naturally can definitely be done successfully through diet, exercise, and supplementation.

1. Diet

Eating a diet rich in particular nutrients can go a long way in boosting testosterone levels naturally [9].

Here are some excellent choices:

  • Pomegranates, Berries, and Cherries: antioxidants
  • Dark, leafy greens: magnesium
  • Fatty fish: Omega-3 fatty acids, vitamin D, and zinc
  • Eggs: healthy fats, protein, and selenium
  • Cocoa products: magnesium and flavonoid antioxidants
  • Avocados: magnesium and boron
  • Shellfish: selenium, zinc, omega-3 fatty acids

2. Exercise

Performing rope exercises

Studies show that high-intensity interval training (HIIT) and resistance training positively impact testosterone levels.

One 4-week study shows men who performed resistance training three days per week experienced improved testosterone levels directly after exercise and in the long term [10].

Additionally, HIIT boosts testosterone levels.

One study found that running on a treadmill for 90 seconds at VO2 max and then 90 seconds at active recovery intervals was more effective than a 45-minute steady-rate run [11].

“Research has shown that lifting heavier weights is the best form of exercise to boost testosterone. As muscle mass increases, it will trigger the body to produce more testosterone.”

-Richard Jadick, D.O.

3. Supplements

Many supplements contain nutrients found in the foods we listed above, like vitamin D, zinc, Omega-3 fatty acids, magnesium, and boron.

There is a progressive decrease in testosterone levels as men age, and high-quality, potent supplements can be very effective in helping the body boost or maintain testosterone levels naturally, promoting muscle gain, increasing energy, and improving sexual function.


Does Finasteride Decrease Free Testosterone?

Finasteride does not decrease free testosterone. Finasteride blocks the enzyme 5α reductase, so there is no conversion of testosterone, which results in DHT suppression and increased free testosterone levels.

Why Does Finasteride Cause ED if It Increases Testosterone?

Finasteride may cause ED while increasing testosterone because it suppresses DHT levels. DHT is more androgenic than testosterone and thus has a significant impact on sexual function, including erectile dysfunction.

Can I Take Finasteride and Testosterone Together?

Taking finasteride and testosterone together appears to be safe for patients with low testosterone and BPH or hair loss. However, taking any medication, including synthetic testosterone, should only be done on doctors' orders and with medical supervision.

So, Does Finasteride Lower Testosterone?

It is unlikely that finasteride is lowering your testosterone, as this medication blocks the conversion of testosterone to DHT, so it is more likely to increase your free testosterone levels.

If you don’t have any particular condition, eating a diet rich in testosterone-boosting nutrients, exercising, and adding an all-natural supplement can be the best formula for boosting your natural testosterone production.

We have compiled a list of testosterone boosters that proved to be top performers in our testing.

Check out the list to find the one that’ll work best for you.


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