Meg Seymour, Ph.D.
Many men experience and want to find a way to stop male pattern baldness (the medical term is androgenetic alopecia). In 1997, the FDA approved the drug finasteride (brand name Propecia or Proscar) for the treatment of male pattern baldness.1 Although there is some evidence that finasteride reduces male pattern baldness, there are side effects to the drug, some of which are serious and can last even after someone stops taking the drug.2 This article will explain what finasteride is, how it works, and its mental and even physical side effects.
What Is Finasteride?
Finasteride is in pill form and was initially approved for the treatment of non-cancerous enlarged prostate.3 At a lower dose than is used to treat the prostate, it is FDA approved to treat hair loss.4 Finasteride is a type of drug called a 5⍺-steroid reductase inhibitor, which means that it prevents the body from converting the hormone testosterone into a different hormone called dihydrotestosterone (DHT). DHT is the hormone responsible for hair loss, so blocking it can help reduce the rate of male pattern baldness and even help hair regrow.4
Women are increasingly being prescribed finasteride for hair loss, as well5, but the drug is not FDA-approved for use in women.6 Because of this, the risks and benefits for women are not well known, but there is some evidence that it can cause birth defects if a woman is pregnant with a male baby.5 Finasteride will only prevent baldness through continued use; if someone stops taking the drug, the benefits of the drug will go away within 12 months, leaving the patient with the same male pattern baldness they had before they took the drug, and they will continue to lose their hair as time goes on.6
What Are the Risks?
Because finasteride is FDA approved only for use by men, most of the data about the safety and side effects are for men. Since long-term side effects were not required to be studied for FDA approval, there is a lack of data on long-term side effects.5 In 2011, the FDA added depression to the drug’s label as a possible side effect after small studies found significant increases in depression for some patients.5 Since 2011, the FDA has received over 700 reports of suicidal thoughts or suicide among those taking finasteride. So why wasn’t the risk for suicide and suicidal thoughts added to the label? In 2021, reporters found that Merck (the makers of brand name Propecia) was aware of reports of suicide and suicidal thoughts but did not want those added to the drug’s label as potential risks.7 A 2015 study of 131 men who reported persistent side effects from taking finasteride found that 73% of those men experienced depression, and 74% experienced anxiety, but anxiety has not been added to the label.2
A study published in 2020 scrutinized over 3,000 reports of side effects from taking finasteride, and found that 89% of those reported side effects were psychological.8 Patients taking finasteride had 4 times the risk of experiencing depression and anxiety, as well as an increased risk of reporting suicidal feelings. These symptoms were more common among those taking finasteride for hair loss, compared to those taking it for another reason such as enlarged prostate. Further, those under 45 years of age were more likely to report suicidal feelings as a side effect.8 However, men who experience hair loss are more likely to report depression compared to other men, so there is a limit to what we can learn from a study that analyzed men who took the drug and reported depression without comparing them to other men with male pattern baldness.1 Scientific research is needed to measure how common these mental health side effects are by comparing men with male pattern baldness who were treated with the drug and those who were given a placebo. Meanwhile, healthcare providers need to be aware of these mental health risks and explain them to patients, deciding together whether the benefits outweigh the risks for that particular patient.1
Depression and anxiety are not the only reported side effects for finasteride. The label cautions that sexual dysfunction, such as erectile dysfunction or low libido, is also a potential side effect of finasteride use.6 Studies have found that erectile dysfunction is found in approximately 3-16% of patients.5 Studies have also found that these side effects sometimes persist for months after the patient stops taking finasteride.2 The persistence of side effects after stopping the drug have been named “post-finasteride syndrome.”4
The Bottom Line
It is important to know that those who experience hair loss are more likely to report depression, so clinical trials are needed to conclusively determine whether finasteride causes depression and anxiety.1 However, studies have documented depression and anxiety among finasteride patients, along with sexual side effects, and symptoms can persist for months or years after stopping the drug.2
All articles are reviewed and approved by Dr. Diana Zuckerman and other senior staff.
The National Center for Health Research is a nonprofit, nonpartisan research, education and advocacy organization that analyzes and explains the latest medical research and speaks out on policies and programs. We do not accept funding from pharmaceutical companies or medical device manufacturers. Find out how you can support us here.
- Ho RS. Ongoing Concerns Regarding Finasteride for the Treatment of Male-Pattern Androgenetic Alopecia. JAMA Dermatology. 2020.
- Ganzer CA, Jacobs AR, Iqbal F. Persistent sexual, emotional, and cognitive impairment post-finasteride: a survey of men reporting symptoms. American Journal of Men’s Health. 2015;9(3):222-8.
- Tacklind J, Fink HA, MacDonald R, Rutks I, Wilt TJ. Finasteride for benign prostatic hyperplasia. Cochrane Database of Systematic Reviews. 2010(10).
- Maksym RB, Kajdy A, Rabijewski M. Post-finasteride syndrome–does it really exist?. The Aging Male. 2019;22(4):250-9.
- Hirshburg JM, Kelsey PA, Therrien CA, Gavino AC, Reichenberg JS. Adverse effects and safety of 5-alpha reductase inhibitors (finasteride, dutasteride): a systematic review. The Journal of Clinical and Aesthetic Dermatology. 2016;9(7):56.
- PROPECIA® (finasteride) [package insert]. Merck & Co; 1992. Available from: https://www.accessdata.fda.gov/drugsatfda_docs/label/2012/020788s020s021s023lbl.pdf
- Levine D, Terhune C. Exclusive: Merck anti-baldness drug Propecia has long trail of suicide reports, records show. Reuters.com. https://www.reuters.com/article/us-merck-propecia-suicide-exclusive/exclusive-merck-anti-baldness-drug-propecia-has-long-trail-of-suicide-reports-records-show-idUSKBN2A32XU. February 3, 2021.
- Nguyen DD, Marchese M, Cone EB, Paciotti M, Basaria S, Bhojani N, Trinh QD. Investigation of suicidality and psychological adverse events in patients treated with finasteride. JAMA Dermatology. 2020 Nov 11.