Does Finasteride Lower Testosterone Levels? All You Need to Know!

This post was most recently updated on June 11th, 2023

If you’re a man looking for hair loss treatments, you probably have heard about Finasteride. However, many believe that it may cause low levels of testosterone in the body, but does Finasteride lower testosterone levels?

It is actually a misconception. Finasteride inhibits 5AR from converting testosterone to DHT, meaning there will be a higher level of “free testosterone” in your body. Testosterone levels are increased indirectly because 5AR doesn’t do its job to make DHT.

Keep reading to learn more about how and why Finasteride does the opposite as well as the impact of these increased testosterone levels backed up by trusted scientific studies.

Demystifying the Fiction around Finasteride

Let’s start with the basics.

Finasteride is a prescription drug that’s sold under the brand name Propecia for hair loss treatment. The second is Proscar that’s used to treat benign prostatic hyperplasia (otherwise known as an enlarged prostate). Here we only cover the testosterone-related side effects of Finasteride (Propecia) as a hair loss treatment.

Uses of Finasteride for Hair Loss

Finasteride (Propecia) is available as a daily oral tablet at a 1mg dosage that you’ll take if you are a Male Pattern Baldness (MPB), or Androgenic Alopecia patient. It’s also one of only two treatments approved by the FDA – another one is Dutasteride (marketed as Avodart).

It has been shown to stop hair loss and even increase hair growth. You’ll notice the first visible results within three to four months and more significant results after one to two years. Hair growth on other body parts won’t be affected. However, Finasteride is not prescribed for all types of hair loss.

Is Finasteride (Propecia) Right For You?

Finasteride (Propecia) is only prescribed for use in adult men with MPB, not recommended for women or children and adolescents. It also isn’t effective at treating types of hair loss that aren’t caused by dihydrotestosterone (DHT), such as telogen effluvium, alopecia areata, and tinea capitis.

Finasteride works by inhibiting the action of Type II 5-alpha reductase, an intracellular enzyme that’s responsible for the conversion of testosterone into a more androgenic hormone, called DHT.

By blocking 5AR, Finasteride can prevent the conversion of testosterone into DHT that would have happened, resulting in hair loss reduction and in some cases, new hair regrowth.

Does Finasteride Lower Testosterone Levels in Reality?

The concept of Finasteride decreasing testosterone levels is actually a myth. Instead, Finasteride will do the opposite. When the conversion of testosterone to DHT is not happening, this can significantly reduce serum DHT levels. Basically, you now have more “free testosterone” in your bloodstream because 5-alpha reductase is inhibited from doing its job to produce DHT.

When your testosterone levels go up, keep in mind that testosterone is also turning into estrogen due to aromatization, meaning your estrogen levels will increase too. If you have an imbalance amount of estrogen and androgen load, you might experience, though rarely, Finasteride-induced side effects (otherwise known as Post-Finasteride Syndrome).

Does the Post-Finasteride Syndrome Exist?

Post-Finasteride Syndrome (PFS) is a set of Finasteride side effects that persist long-term and even after stopping the medication. According to the Post-Finasteride Syndrom Foundation, the symptoms of PFS can vary widely, such as:

• Erectile dysfunction
• Decreased libido
• Problems with ejaculation
• Breast enlargement and/or tenderness
• Chronic fatigue
• Depression and anxiety
• Difficulty recalling memory

However, this only occurs in a small group (below 2%) of men who took Finasteride and it’s very rare. And some side effects don’t have strong science-backed proof.

Scientific Evidence

A one-year trial shows the side effects in male pattern baldness patients who take 1mg of Finasteride per day.

• 1.8% of men reported decreased libido
• 1.3% of men reported erectile dysfunction
• 1.2% of men reported ejaculation disorder

However, the differences in side effect percentage between the patients who take Finasteride and the patients who received a placebo are pretty small.

• 1.3% of men reported decreased libido
• 0.7% of men reported erectile dysfunction
• 0.7% of men reported ejaculation disorder

Another Randomized Controlled Trial suggests that the nocebo effect is another crucial factor. This refers to a psychological phenomenon where negative beliefs about a particular medication can lead them to experience adverse symptoms. The researchers found that the men who know about the side effects were approximately 3X as likely to report sexual side effects.

Let’s find out first why it happens.

Decoding Low Libido and Erectile Dysfunction Factors

The cause of PFS is estrogen imbalance. Finasteride can increase your testosterone by 15%, which then aromatizes into estrogen. On the other hand, you have a 70% drop in DHT in your body, which indirectly boosts your estrogen levels.

It is worth noting that DHT is the most androgenic hormone that acts as an antagonist of estrogen. That’s why even if you have normal levels of estrogen, you can be estrogen dominant because there’s insufficient androgen load in your body. You need healthy levels of estrogen and androgen load to maintain your sexual function.

Post-Finasteride Syndrome happens because you have low levels of androgen load, not testosterone.

Therefore, it is recommended to check your baseline total testosterone, DHT, free testosterone, and estradiol before starting the medication. If you don’t know what your hormone profile looks like before Finasteride, you will also have no clue what to refer to if side effects occur.

Solutions for the Post-Finasteride Syndrome

Clinical research shows that PSF is irreversible. However, if it is seen as a consequence of the decrease in systemic androgen load, hormonal manipulation can be a solution to it by activating your androgen receptors using any androgen. For instance,

• You may need to take Finasteride together with exogenous testosterone replacement therapy to maintain the androgenicity of your testosterone on the limit of high-normal levels. Always speak to your doctor first if testosterone therapy is right for you.
• Mesterolone (Proviron) can be used for treating PFS. It is a very androgenic hormone but more tissue-selective than DHT. Proviron is effective to regulate the androgen load in a dose-dependent manner. Again, consult with a doctor before starting the dose.

There are also things to do to maintain your androgen levels naturally to prevent PFS from happening, such as lifestyle, diet, and supplements.

• Get proper sleep.
• Exercise and gain muscle, such as doing cardio or joining a gym.
• Maintain a body fat percentage of 10-20% to help lower estrogen levels and increase testosterone.
• Eat enough healthy fats and fibers, such as broccoli, green tea, pomegranate, and whole grains (oat, corn, and rice).
• Take daily supplements to support your diet, such as creatine monohydrate, boron, vitamin D, and Tribulus.
• Stay clear from personal care products that contain ingredients that are linked to hormone disruption, such as parabens.

Overall, it is important for you to monitor your testosterone levels and speaks with your healthcare provider if they have any concerns. Read our article to learn more about how to reduce DHT levels naturally.

Conclusion – Finasteride Increases Testosterone Levels but…

Finasteride will not lower your testosterone levels instead increase it. It blocks the action of type II 5-ARI to convert testosterone into DHT, so there’s more “free testosterone” in your body that’s left unconverted. The estrogen levels may also increase due to aromatization.

However, if the amount of estrogen and androgen load is imbalanced, this may lead to side effects (also known as Post-Finasteride Syndrome. Fortunately, it is reversible through hormonal manipulation, a healthy diet & lifestyle, and physical activity. Speak to your doctor before starting Finasteride and immediately seek medical attention if the side effects persist long-term.

The information provided in this article is not a substitute for professional medical advice instead for informational purposes only. Always talk to your doctor about the risks and benefits of Finasteride.

Frequently Asked Questions

How much Finasteride reduces testosterone?

Finasteride doesn’t reduce testosterone levels in your body, instead, it reduces prostatic DHT by up to 90% and serum DHT levels by 70%. It is also shown to improve testosterone levels by 15% to 25% within two years.

Does Finasteride cause muscle loss?

Health Canada reported that taking 5mg of Finasteride tablets may cause myopathy, muscle pain, and muscle weakness. However, more studies are needed to give sufficient data regarding muscle-related side effects.

Does Finasteride actually cause ED?

The actual cause of ED is DHT inhibition can also lead to testosterone aromatizing into estradiol, the primary estrogen hormone. A high level of estrogen and a low level of testosterone may cause sexual disorders, such as ED, erectile dysfunction, and ejaculation disorder.

References

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Health Canada. (2017, June 22). Summary Safety Review – Finasteride – Assessing the Potential Risk of Serious Muscle-Related Side Effects. Retrieved from https://www.canada.ca/en/health-canada/services/drugs-health-products/medeffect-canada/safety-reviews/summary-safety-review-finasteride-assessing-potential-risk-serious-muscle-related-side-effects.html 

Jerry Shapiro, Keith D. Kaufman. Use of Finasteride in the Treatment of Men With Androgenetic Alopecia (Male Pattern Hair Loss). Journal of Investigative Dermatology Symposium Proceedings. Volume 8, Issue 1. 2003. https://doi.org/10.1046/j.1523-1747.2003.12167.x

Marks LS. 5alpha-reductase: history and clinical importance. Rev Urol. 2004;6 Suppl 9(Suppl 9):S11-21. PMID: 16985920; PMCID: PMC1472916.

Mondaini N, Gontero P, Giubilei G, Lombardi G, Cai T, Gavazzi A, Bartoletti R. Finasteride 5 mg and sexual side effects: how many of these are related to a nocebo phenomenon? J Sex Med. 2007 Nov;4(6):1708-12. doi: 10.1111/j.1743-6109.2007.00563.x. Epub 2007 Jul 26. PMID: 17655657.

Schulster M, Bernie AM, Ramasamy R. The role of estradiol in male reproductive function. Asian J Androl. 2016 May-Jun;18(3):435-40. doi: 10.4103/1008-682X.173932. PMID: 26908066; PMCID: PMC4854098.

Zito PM, Bistas KG, Syed K. Finasteride. [Updated 2022 Aug 25]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK513329/