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Is Finasteride Safe?
Dr. Michael May (FRCS)
Medically reviewed by
Dr. Michael May (FRCS)
Updated on August 21, 2023

Finasteride is the most commonly prescribed hair loss medication [1]. More than two-thirds of clinics say they often prescribe this drug to their patients — so trichologists tend to agree that Finasteride is a safe medication.

Long-term large-scale studies suggest that Finasteride can be taken for months or even years without causing side effects for a significant number of patients [2-3]. But prospective Finasteride users should know about its potential side effects, especially if you’re concerned about the safety of Finasteride.

In this article, you’ll learn:

  • how safe Finasteride is
  • what Finasteride side effects can occur
  • how to decide if Finasteride is safe for you to take.
Table of Contents

How safe is Finasteride?

While there’s a lot of anecdotal and research-based evidence of side effects related to Finasteride, it’s important to note that these affect a very small proportion of people. According to one research report, Finasteride has a “well-established, excellent safety profile” [4].

In one 10-year study of 532 male Finasteride patients, researchers recorded mild, temporary side effects in 36 participants [3]. These included lower libido and erectile dysfunction. The effects were so mild that none of the affected patients stopped taking Finasteride.

Finasteride was originally developed to treat patients with an enlarged prostate. As well as treating hair loss, it’s still regularly prescribed to patients with benign prostate enlargement (BPE). So the drug has gone through rigorous safety tests in order to be licensed as a drug for medical as well as cosmetic use.

Men who take Finasteride for BPE tend to take a higher dose (5mg a day) than those who use it to stop male pattern baldness (1mg a day). Research suggests even higher doses put men at only slightly higher risk of developing side effects [2].

Sexual side effects of Finasteride

Finasteride-related erectile dysfunction is arguably the drug’s most well-known side effect. And it’s true that several patients have reported sexual side effects when taking Finasteride. A 2011 campaign by the FDA in the US led to much greater awareness of Finasteride’s potential side effects [5].

But more widespread knowledge doesn’t equate to more prevalence of these side effects. Multiple studies have found that Finasteride sexual side effects impact a very small proportion of users. One review of 73 research papers found that sexual dysfunction affects just 2.1% to 3.8% of patients taking Finasteride [6]. Erectile dysfunction was the most common sexual side effect, followed by ejaculatory dysfunction and lowered libido.

A comprehensive review found that when used in higher doses to treat benign prostate hyperplasia (BPH), Finasteride was infrequently associated with ejaculation, erection, and libido problems [7]. However, it’s important to note that the dosage of Finasteride for BPH is typically around 5 times higher than the hair loss treatment dosage.

Another study found adverse sexual side effects in 1.2% to 1.8% of Finasteride users [4]. Side effects quickly resolved themselves among those who stopped taking the drug.

Finasteride has also been linked with a “nocebo” effect [8]. That means the patient’s negative expectations of the drug can trigger or worsen symptoms, rather than being caused solely by the drug itself.

Ultimately, there’s a very low chance you’ll experience erectile dysfunction and other sexual side effects from using Finasteride [9].

Finasteride and fertility

Finasteride affects your hormones. So it’s understandable to have concerns about whether Finasteride affects fertility, especially if you’re thinking of having a baby in the near future.

There’s a slight chance that Finasteride can decrease your sperm count [10]. When you stop taking the medication, sperm count usually returns to normal very quickly (although your hair loss may resume) [10-11].

Some research claims there are no apparent adverse links between Finasteride use and sperm production [12]. But in general, it’s a good idea to speak to your doctor if you’re taking (or planning to take) Finasteride, and you and your partner are planning to try for a baby.

Propecia — the brand name for Finasteride — carries a warning against pregnant women handling tablets containing Finasteride due to potential complications with male foetuses [13]. This is one reason why Finasteride for women isn’t usually recommended.

While healthy babies have been born despite exposure to Finasteride, you should still be aware of the risks of Finasteride in pregnancy and take precautions where you can.

Finasteride and mental health

Recent research from 2020 has highlighted a potential link between Finasteride, suicidal thoughts, and other mental health concerns [14]. This seems to be particularly prevalent in men under 45 taking the drug to treat androgenetic alopecia (male pattern baldness).

More research is needed to understand the link between mental health and Finasteride use. Researchers suggest it could be influenced by:

  • The impact of sexual side effects
  • Younger patients being more vulnerable to Finasteride’s adverse effects
  • A nocebo effect — including more reporting due to heightened awareness of the potential connection between Finasteride and mental health.

This research is in its infancy, but if you’re concerned about your mental health — regardless of whether you believe it could be linked to Finasteride use — it’s important that you get the right support. Your GP can help you get the help you need.

Learn more about anxiety and hair loss, and depression and hair loss.

Finasteride and male breast cancer

There are very rare instances of Finasteride use leading to gynecomastia and breast cancer in men. By 2010, 50 cases of male breast cancer had been linked to Proscar (Finasteride 5mg) use, and 3 cases had been linked to Propecia (Finasteride 1mg) [15]. More recent research from 2017 has also found an association between Finasteride use and male breast cancer [16].

It’s important to note that these numbers are extremely small compared with the number of Finasteride users. In 2013, more than 1.5 million patients took Finasteride in the US alone [17]. So the proportion of Finasteride users who go on to develop breast cancer is very small.

However, if you experience symptoms including breast lumps, nipple discharge, or changes to your nipple, book an appointment with your GP immediately, as these can be signs of breast cancer.

It’s also worth noting that the majority of Finasteride-linked male breast cancer cases are associated with the higher 5mg dose. Most people who take Finasteride for alopecia take the 1mg dose, further slashing your risk profile.

Post-Finasteride syndrome

Most patients stop experiencing side effects when they discontinue Finasteride [4, 6]. But some report ongoing symptoms after they stop taking the drug. This is known as post-Finasteride syndrome (PFS) [9, 18].

Post-Finasteride syndrome is characterised by side effects including erectile dysfunction, low libido, depression and anxiety which linger after they stop taking the medication.

Limited research has been conducted into PFS. It’s only recently been recognised as a potential clinical problem, so a lot more research is needed to establish the facts around PFS. However, some researchers note that, like with some other safety concerns related to Finasteride, the nocebo effect may affect a significant proportion of patients [19].

Should you take Finasteride?

Ultimately, it’s up to you whether you take Finasteride for hair loss and hair regrowth. Research shows Finasteride to be a safe, effective drug, though side effects can cause problems for a very small percentage of patients. Learn whether Finasteride works and how long Finasteride takes to slow hair loss.

To put the risks in perspective, one large study of 3,177 patients found adverse reactions in 23 Finasteride users (0.7%) [20]. Of these, just 7 men stopped taking Finasteride after weighing up the benefits versus the risks.

If you’re worried about Finasteride safety, it’s worth consulting with your doctor before you start a course of Finasteride. This is particularly the case if you’re a man and:

  • Your partner is pregnant and/or breastfeeding
  • You’re planning to try for a baby soon
  • You have a history of mental health issues.

Otherwise, it’s entirely up to you. Side effects are rare — but only you can decide if the benefits outweigh the risks.

Some men avoid taking Finasteride over safety concerns. In these cases, their hair loss often continues even after a hair transplant, leading them to need multiple hair transplants in future.

Finasteride results are excellent for hair loss patients. It can prevent progression of hair loss in more than 95% of patients [20]. But there are also alternatives to Finasteride you can take if you’re worried about Finasteride safety. See our comparisons of Finasteride vs Dutasteride and Finasteride vs Minoxidil to learn more.

If you’re considering using Finasteride, speak to an impartial hair loss consultant to help you decide whether to take this hair loss drug. If you decide Finasteride isn’t for you, we can help you find the right treatment to restore your hair. Book your free consultation at the Wimpole Clinic to get professional, impartial guidance on how to treat your hair loss.

Is Finasteride Safe?, Wimpole Clinic

  1. ISHRS Practice Census 2022
  2. Longitudinal analysis of sexual function reported by men in the Prostate Cancer Prevention Trial
  3. Long-term (10-year) efficacy of finasteride in 523 Japanese men with androgenetic alopecia
  4. Use of Finasteride in the Treatment of Men With Androgenetic Alopecia (Male Pattern Hair Loss)
  5. Global online interest in Finasteride sexual side effects
  6. Finasteride and sexual side effects
  7. Medical therapy for benign prostatic hyperplasia: sexual dysfunction and impact on quality of life
  8. Finasteride 5 mg and sexual side effects: how many of these are related to a nocebo phenomenon?
  9. Risk of erectile dysfunction associated with use of 5-α reductase inhibitors for benign prostatic hyperplasia or alopecia: population based studies using the Clinical Practice Research Datalink
  10. Finasteride use in the male infertility population: effects on semen and hormone parameters
  11. Finasteride-associated male infertility
  12. Effect of 1-mg Dose of Finasteride on Spermatogenesis and Pregnancy
  13. Propecia label | FDA
  14. Investigation of Suicidality and Psychological Adverse Events in Patients Treated With Finasteride
  15. MHRA: The risk of male breast cancer with Finasteride
  16. Finasteride treatment and male breast cancer: a register-based cohort study in four Nordic countries
  17. Finasteride | Drug Usage Statistics, United States, 2013 – 2020
  18. Post-Finasteride syndrome: An emerging clinical problem
  19. Post-Finasteride syndrome: a surmountable challenge for clinicians
  20. Evaluation of efficacy and safety of finasteride 1 mg in 3177 Japanese men with androgenetic alopecia
Dr. Michael May (FRCS)
Medically reviewed by Dr. Michael May (FRCS)Updated on August 21, 2023
The Wimpole Clinic offers FUE Hair, Beard & Eyebrow Transplants & Trichology.
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