Finasteride and Testosterone: Does Finasteride Increase or Lower Testosterone?

Testosterone and dihydrotestosterone (DHT) are both male sex hormones called androgens. While testosterone is often considered the main male hormone, DHT is a more powerful androgen that plays a role in several processes within the body.

The body converts some testosterone into DHT using an enzyme called 5-alpha reductase.

The process works like this:

Testosterone → 5-alpha reductase enzyme → DHT

Finasteride works by blocking the 5-alpha reductase enzyme, reducing the amount of testosterone that is converted into DHT.

This is why finasteride is effective for male pattern hair loss: DHT contributes to the shrinking of hair follicles in genetically susceptible men.

Yes, finasteride can slightly increase testosterone levels.

Because less testosterone is being converted into DHT, more testosterone remains available in the bloodstream. Clinical studies have found that testosterone levels may increase by approximately 10–20% in some men taking finasteride.

However, this does not mean finasteride acts as a testosterone booster.

The increase is generally:

• Small
• Within normal physiological levels
• Not associated with noticeable changes in strength, muscle size or appearance

No. One of the biggest misconceptions about finasteride is that it lowers testosterone.

Finasteride does not stop the body from producing testosterone. Instead, it reduces the conversion of testosterone into DHT.

For most men:

• Testosterone production continues normally
• Testosterone levels remain healthy
• DHT levels decrease

This hormonal change is why finasteride can help slow hair loss without significantly affecting testosterone levels.

Yes. Lowering DHT is the main way finasteride works.

DHT is a hormone linked to:

• Male pattern hair loss
• Prostate growth

In some men, hair follicles are more sensitive to DHT because of their genes. Over time, DHT causes these hair follicles to shrink, making hair thinner and shorter until it may stop growing altogether.

By reducing DHT levels, finasteride can help protect hair follicles and slow further hair loss.

Some men worry that the small increase in testosterone caused by finasteride could affect muscle growth or gym performance.

Current research suggests this is unlikely. Although testosterone levels may rise slightly, the increase is usually too small to have a noticeable effect on muscle mass, strength or athletic performance.

No evidence suggests that finasteride makes men less masculine.

Because finasteride reduces DHT, some people worry it may affect characteristics associated with masculinity. However, testosterone levels usually remain normal, and most men do not experience changes in:

• Muscle mass
• Voice
• Body composition
• Male characteristics

Finasteride works by lowering DHT, the hormone that causes male pattern hair loss. It doesn’t reduce all male hormones in the body.

Some men taking finasteride report sexual side effects, which may include:

• Reduced sex drive
• Erectile difficulties
• Changes in ejaculation

However, these effects are not caused by lowering testosterone in most cases. The relationship between finasteride, DHT and sexual function is complex and still being researched.

Finasteride is not an oestrogen medication and does not directly increase oestrogen.

However, because finasteride may slightly increase testosterone, some testosterone can potentially be converted into oestrogen through a process called aromatisation.

For most men, any changes are small and do not cause noticeable effects.

Finasteride does not usually lower testosterone. Instead, it reduces the conversion of testosterone into DHT, which is the hormone mainly responsible for male pattern hair loss.

While finasteride may cause a small increase in testosterone levels, this is generally not enough to affect muscle growth, appearance or masculinity.

For men using finasteride for hair loss, the main hormonal change to expect is lower DHT – not lower testosterone.