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Does Finasteride Lower Testosterone Levels?
Dr Luciano Sciacca (GMC)
Medically reviewed by
Dr Luciano Sciacca (GMC)
Updated on March 20, 2024

Finasteride is a popular hair loss medication. Always or often recommended by more than two-thirds of hair loss specialists, Finasteride is proven to create great results for those experiencing male pattern baldness [1]. 

But there are known side effects of Finasteride, which may deter some men from using it. That’s because Finasteride works by changing your hormone levels, including testosterone. 

So does Finasteride lower testosterone, and if so, what impact does this have on your hair and body?

Table of Contents

How does Finasteride work?

Finasteride is a medication that prevents enzymes in your body from converting testosterone to dihydrotestosterone. Dihydrotestosterone, or DHT, is the hormone that causes male pattern baldness, or androgenetic alopecia. So less DHT is good news for men with hair loss.

Finasteride chemical structure

What’s the difference between testosterone and dihydrotestosterone?

Both testosterone and dihydrotestosterone are androgens, or male sex hormones. They’re both necessary for organ development and function, especially in childhood. But there are key differences between the two:

  • DHT is more potent than testosterone [2]. It binds more strongly to androgen receptors in your hair follicles, which causes them to shrink. 
  • DHT levels can be reduced safely in adulthood. While DHT is needed for physical development in childhood, it’s less necessary after puberty.
  • It’s normal to have much lower levels of DHT than testosterone [2-3]. Experts say a normal range of testosterone is 270 to 1070 ng/dL (depending on age), while a healthy DHT range is 14 to 77 ng/dL.

How does Finasteride impact testosterone levels?

By blocking the conversion of testosterone to DHT, Finasteride lowers your DHT levels. But in turn, this actually raises your testosterone levels [4]. That’s because less testosterone is being converted, so it remains in your body in its original form.

Research suggests that taking a 5mg Finasteride tablet each day can result in a drop of up to 93% in DHT, and a rise of up to 25% in testosterone [5]. (Bear in mind that 5mg isn’t a typical dose for treating hair loss — most men take 1mg of Finasteride a day for this purpose).

Why does Finasteride cause erectile dysfunction if it increases testosterone?

Erectile dysfunction is a known side effect of Finasteride, and it’s associated with low testosterone levels. So why does it happen if Finasteride increases testosterone?

DHT is the active androgen that helps you maintain an erection. So despite the increase in testosterone, the reduction in DHT may reduce your ability to get or maintain an erection.

Fortunately, erectile dysfunction is a rare side effect, impacting only 1.3% of Finasteride users [6].

Does stopping Finasteride increase testosterone?

No. Stopping Finasteride will increase DHT levels, but it won’t increase testosterone. In fact, your testosterone levels will probably dip: more testosterone is converted to DHT, so there’s less testosterone circulating.

When you stop taking Finasteride, hair loss is likely to resume. If you want to stop taking Finasteride without losing your hair, you might consider switching to topical Finasteride, which can maintain your hair while reducing the risk of side effects [7].

Can I build muscle on Finasteride?

Some research has linked Finasteride with reductions in body mass index (BMI) in men [4]. So does this mean Finasteride inhibits muscle growth?

The research is limited, but one study has shown that Finasteride didn’t inhibit the increase of muscle mass in people taking testosterone enanthate (TE) [8]. While the musculoskeletal outcomes were the same in those taking Finasteride with TE and those just taking TE, Finasteride didn’t prevent men from gaining muscle.

Testosterone enanthate is an artificial anabolic steroid, which makes it a key contributor to these muscle gains. However, it should be used with caution. Speak to your doctor before considering the use of TE to build muscle.  

Can you take Finasteride if you’re on testosterone replacement therapy (TRT)?

Yes, it’s usually safe to take Finasteride alongside TRT therapy. Both treatments will increase your testosterone levels, but TRT also increases your DHT levels. Finasteride may reduce DHT levels, but it’s unlikely to significantly affect the outcome of TRT [8]. 

TRT is usually prescribed to those who have low testosterone levels, so most people’s testosterone levels will stay within the normal range even when taking both testosterone replacement drugs and Finasteride.

A rise in DHT levels can be beneficial for some patients, so weigh up the pros and cons of taking Finasteride alongside TRT. 

To be on the safe side, track your testosterone and DHT levels throughout your treatment.

Should you take Finasteride for your hair loss?

Finasteride is a safe, effective drug for male hair loss. Finasteride for transgender patients may sometimes be recommended, too. Studies show it can reduce crown hair loss by 83% and slow frontal balding by up to 70% [9].

Patient before and after 6 months of taking 1mg oral Finasteride per day.
Patient before Finasteride treatment and after 6 months of taking 1mg per day [3]


But is it the right treatment for you? It could be, if:

  • You’re still in the early stages of hair loss.
  • You’re ready to commit to a long-term hair loss treatment.
  • You are aware of the potential side effects of Finasteride.

Take a look at these Finasteride results to help decide if this is the right treatment for your hair loss.

Does Finasteride Lower Testosterone Levels?, Wimpole Clinic

Dr Luciano Sciacca (GMC)
Medically reviewed by Dr Luciano Sciacca (GMC)Updated on March 20, 2024
The Wimpole Clinic offers FUE Hair, Beard & Eyebrow Transplants & Trichology.
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