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LibraryHair Loss TreatmentsFinasteride for Hair Loss: What to Expect
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Handsome, smiling brunette male wearing a pale blue and white striped dress shirt running his hand through his hair and looking off to the side.

Finasteride for hair loss: what to expect

Written by
XYON Medical Team
Clinically reviewed by
Dr. C. Han, MD, FRCPC

Every decision you make about your health should be an informed decision. Here are 7 essential facts about using finasteride for hair loss that can start you on your journey to better hair. This is not an exhaustive list and any additional questions or concerns you might have about hair loss or hair loss treatments should be directed to a physician.

What is finasteride?

  • Finasteride is a 5-alpha reductase inhibitor.

Finasteride is currently the most effective FDA-approved treatment for male pattern hair loss. It’s available in both pill and topical forms, but only the pill is FDA-approved. Finasteride belongs to a category of medications called 5-alpha reductase inhibitors.

How does finasteride work?

  • Finasteride lowers DHT, the hormone that causes male pattern hair loss.

All members of the 5-alpha reductase family are designed to target different forms of an enzyme called 5-alpha reductase. The enzyme converts the male sex steroid hormone testosterone into dihydrotestosterone (DHT).

DHT has several effects on the body. At high levels in the scalp, it causes male pattern hair loss. The hormone binds to attachment sites on hair follicles, initiating a process called miniaturization. Miniaturization causes follicles to shrink and gradually stop producing viable hairs.

Finasteride binds to the enzyme, preventing testosterone from attaching and being converted to DHT. This blocking action helps reduce local DHT levels, slowing down the hair loss process.

How long does it finasteride take to work?

  • It might take 9-12 months before you see results with finasteride.

Generally, you will need to take finasteride for a minimum of 9-12 months before noticeable changes occur. You should know that using finasteride for hair loss is a commitment. It helps slow down the hair loss process, but only if it’s taken consistently. If you stop taking finasteride, you’ll lose any regrowth within a matter of weeks.

Finasteride works on the entire scalp, but research has shown it may be slightly more effective in the vertex region of the scalp (the top of the head). Results may also be more significant in men with mild to moderate hair loss.

Remember, success in hair loss treatments include maintaining existing hairs as well as new regrowth. Male pattern hair loss is a genetically-driven and progressive condition and so without treatment, thinning will continue.

If finasteride effective?

  • Long term clinical studies have shown that 90% of men either maintain or see improvements in hair growth while on finasteride.

Finasteride lowers blood levels of DHT by approximately 60%. Over time, this reduction has been shown to be significant enough to slow the progression of pattern hair loss and support strong regrowth that stands the test of time.

To put things into perspective, a multi-national 5 year efficacy study found that 75% of men who received placebo instead of finasteride experienced progressive and visible hair loss by the end of the study (Shapiro & Kaufman, 2003).

What are the side effects of finasteride for hair loss?

  • Finasteride is safe, but some men have reported experiencing sexual side effects, depression and shedding while on the medication.

Finasteride is generally well-tolerated. It does have some associated side effects, but these are usually mild, resolve with time and affect a subset of finasteride users. In one large scale study, the incidence of sexual side effects was about 4% after 1 year of treatment (Sato & Takeda, 2012).

Common side effects
The most commonly reported side effects of finasteride are sexual. These include: erectile dysfunction, decreased ejaculatory volume, decreased sex drive and breast enlargement or swelling (Salisbury & Tadi, 2021). They are likely due to finasteride’s effect on DHT and testosterone levels in the blood.

Finasteride has also been associated with depression. It is possible that finasteride may affect blood levels of hormones that are important to brain development and function.

Shedding associated with starting finasteride
Some men notice increased shedding within the first few weeks of starting finasteride. This is normal. Finasteride helps reset the growth cycle of hair and this process results in older hairs being pushed out to make room for new growth.

If this shedding continues for longer than a few months, we recommend that you consult with a doctor to determine whether there might be another explanation for your increased hair loss.

Increased prostate cancer risk
Use of finasteride has been linked to an increased risk of high-grade prostate cancers. This may be due to the medication’s potential to change how cells respond to androgens.

But there is also contradicting data that finasteride could actually help reduce the incidence of less aggressive tumours (Thompson et al., 2013). In the absence of a confirmed causal relationship, we recommend that you consult with a doctor about your individual risk.

Other important safety considerations for finasteride

  • Women who are, or could become pregnant should not use or come into contact with finasteride. You also won’t be able to donate blood while taking the medication.

Because finasteride lowers DHT, a hormone critical to male sexual development, women who are or could become pregnant must not take finasteride. As an extra precaution, women of childbearing age should also avoid handling crushed or broken pills.

The American Association of Blood Banks recommends that finasteride users wait one month after their last dose of the medication before donating blood. This is to reduce the potential risk to female transfusion recipients of childbearing age.

Topical finasteride: is it right for you?

  • For some men, topical finasteride may be an option. A physician will make a recommendation based on your individual needs and medical history.

Topical preparations of finasteride are becoming an increasingly popular alternative to the oral pill. Clinical data shows that it works just as well and has potentially fewer side effects. But like the pill, topical finasteride needs to be applied consistently for you to reap the full benefits.

SiloxysSystem™ Gel is a drug delivery system that was developed with your safety and wellness in mind. This sophisticated gel carrier concentrates finasteride at the scalp and releases it over time to minimize unwanted absorption through the skin. It is only available with a physician’s consultation and prescription.

If you have any other questions about finasteride, XYON is pleased to connect you with an independent, board-certified dermatologist to start you on your journey to better hair.


Cranwell, W., & Sinclair, R. (2016). Male Androgenetic Alopecia. Endotext.

Diviccaro, S., Melcangi, R. C., & Giatti, S. (2020. May). Post-finasteride syndrome: an emerging clinical problem. Neurobiology of Stress, 12.

Finasteride. (n.d.). Drugbank Online.

Ho, C. H., Sood, T., & Zito, P. M. (2021). Androgenetic alopecia. StatPearls. StatPearls Publishing.

Salisbury, B. H., & Tadi, P. (2021). 5 Alpha Reductase Inhibitors. StatPearls. StatPearls Publishing.

Sato, A., & Takeda, A. (2012, Jan). Evaluation of efficacy and safety of finasteride 1 mg in 3177 Japanese men with androgenetic alopecia. The Journal of Dermatology, 39(1), 27-32.

Shapiro, J., & Kaufman, K. D. (2003, Jun). Use of finasteride in the treatment of men with androgenetic alopecia (male pattern hair loss). Journal of Investigative Dermatology Symposium Proceedings, 8(1), 20–23.

Shin, S. Y., Shin, Y. H., Lee, S. W., Shin, J. Y., & Kim, C. H. (2011, December 28). Blood donors on teratogenic drugs and donor deferral periods in a clinical situation: blood donors on teratogenic drugs. Vox Sanguinis, 102(4), 362–364.

Thompson, I. M., Goodman, P. J., Tangen, C. M., Parnes, H. L., Minasian, L. M., Godley, P. A., Lucia, M. S., & Ford, L. G. (2013, August 15). Long-term survival of participants in the prostate cancer prevention trial. New England Journal of Medicine, 369(7), 603–610.

Traish, A. M., Mulgaonkar, A., & Giordano, N. (2014, June). The dark side of 5α-reductase inhibitors’ therapy: sexual dysfunction, high gleason grade prostate cancer and depression. Korean Journal of Urology, 55(6), 367–379.

Wang, L., Lei, Y., Gao, Y., Cui, D., Tang, Q., Li, R., Wang, D., Chen, Y., Zhang, B., & Wang, H. (2020, April). Association of finasteride with prostate cancer. Medicine, 99(15).

Zito, P. M., Bistas, K. G., & Syed, K. (2022). Finasteride. StatPearls.

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The content within this article and XYON’s Knowledge Library is intended to be used for educational purposes only. It is not a substitute for medical advice. You should always con­sult with a licensed healthcare provider for all mat­ters relat­ing to your health. XYON is not compensated for links to third-party sites that appear within this article. The opinions expressed on third-party sites do not reflect the views and opinions of XYON’s medical writers, physicians or the company.

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