Finasteride is the most commonly prescribed hair loss medication [1]. More than two-thirds of hair restoration 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]. However, prospective Finasteride users should know about its potential side effects, especially if they’re concerned about the safety of Finasteride. In this article, we’ll explore:
Finasteride is a DHT blocker. In individuals with male pattern baldness, dihydrotestosterone (DHT) binds to androgen receptors in the hair follicles which causes them to shrink. As the follicles shrink, they eventually stop producing hair, which in turn leads to hair loss.
Finasteride helps to reduce enzymes from converting testosterone to DHT. As a result, less DHT binds to the sensitive androgen receptors allowing the affected hair follicles to produce hair again.
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 who are suffering from an enlarged prostate due to Benign Prostatic Hyperplasia (BPH). As well as treating hair loss, it’s still regularly prescribed to patients with BPH. So the prescription 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 BPH 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].
Finasteride-related erectile dysfunction is arguably the drug’s most well-known side effect. Several patients have indeed 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].
However, more widespread knowledge doesn’t equate to more prevalence of these side effects. Multiple studies have found that Finasteride’s 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 prostatic 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 persistent sexual side effects that may impede sexual function from using Finasteride [9]. Find out more about whether Finasteride side effects are permanent.
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 or healthcare professional 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 Finasteride tablets 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.
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 hair loss).
More research is needed to understand the link between mental health and Finasteride use. Researchers suggest it could be influenced by:
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 or health care professional can help you get the help you need.
Learn more about anxiety and hair loss.
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 United States 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 doctor 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 to treat hair loss take the 1mg dose, further slashing your risk profile.
It should be noted that more recent evidence suggests there’s no correlation between Finasteride use and high-grade prostate cancer [21].
Most patients stop experiencing side effects when they discontinue Finasteride [4, 6]. However, 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 more research is needed to establish the facts regarding 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].
According to the NHS, St John’s wort (an herbal remedy used to treat depression) may affect the effectiveness of Finasteride.
As always, it is recommended that you make sure to speak with your doctor or healthcare professional about drug interactions if you are taking any other prescription drugs, over-the-counter medicines, supplements, or herbal remedies in addition to Finasteride.
As with any medication, some individuals may experience hypersensitivity in the form of an allergic reaction. Allergic reactions to Finasteride are rare but are nonetheless, very serious. Seek medical care immediately if you experience any of the following symptoms of a serious allergic reaction which are as follows:
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:
Otherwise, it’s entirely up to you. Side effects are rare — but only you can decide if the benefits outweigh the risks and if Finasteride is worth it.
Finasteride results are excellent for hair loss patients as it can prevent the progression of hair loss in more than 95% of patients [20]. However, 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.
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 to promote hair growth, 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.
Long-Term Effects of Finasteride on Prostate Cancer Mortality
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