If you’ve been researching Finasteride for hair loss, you may have read some unsettling stories online that describe ongoing side effects long after stopping the medication. These accounts often mention something called Post-Finasteride Syndrome, or PFS.
Naturally, these can be worrying. You might be thinking twice about starting treatment, feel uncertain about continuing it, and have a lot of unanswered questions: Is PFS real? How common is it? And should it influence your treatment decisions?
In this guide, we’ll break down what we know (and don’t yet know) about PFS. We’ll explain the reported symptoms, what the current evidence shows, and what to do if you’re worried.
The key points:
Post-Finasteride Syndrome (PFS) refers to persistent symptoms after stopping Finasteride, most commonly sexual dysfunction.
It’s not officially recognised as a medical condition in the UK, but some patients report serious and ongoing effects.
Evidence around PFS is limited and mixed, with studies showing rare but significant cases.
Many reported symptoms may have other causes, making diagnosis complex.
For most people, Finasteride is well-tolerated and side effects resolve after stopping.
If you’re worried about symptoms, speak to a healthcare professional before stopping treatment.
What is post-Finasteride syndrome?
Post-Finasteride Syndrome refers to a group of ongoing symptoms that some people report after stopping Finasteride (1). It is not the same as the side effects that happen when using Finasteride and clear after treatment. The hallmark of PFS is that it’s ongoing, even after the medication has stopped.
The Post Finasteride Syndrome (PFS) Foundation is a non-profit organisation dedicated to helping fund research on the characterization, underlying biological mechanisms, and treatments of PFS while improving public awareness of the condition. They define this condition as enduring sexual dysfunction that persists after stopping treatment with a 5 alpha-reductase inhibitor (Finasteride, Dutasteride). This can include loss of libido, Erectile Dysfunction, and loss of genital sensation and orgasmic function.
Currently, PFS is not officially recognised as a distinct medical condition by organisations like the NHS, and there is no universally accepted clinical definition. The most widely cited diagnostic criteria were proposed in 2022 by Healy et al. and require sexual dysfunction to last for 3 or more months after discontinuing Finasteride (2).
Post finasteride syndrome has caused much controversy. Essentially there is not enough high-quality clinical data about this condition, which has led to many medical professionals denying its existence. However, it has been listed in the National Institutes of Health’s Genetic and Rare Diseases Information Centre in the USA, and the FDA and MHRA have cited longstanding sexual dysfunction as a possible consequence of treatment.
Despite the lack of official definitions, it doesn’t mean the experiences of patients aren’t real or that they should be ignored. Many researchers and clinicians acknowledge the need for further investigation, and studies in this area are ongoing.
How does Finasteride work?
Finasteride works by acting on the enzyme 5alpha reductase, to stop the conversion of testosterone into its active metabolite Dihydrotestosterone or DHT. DHT acts on hair follicles to cause miniaturisation, causing them to become shorter and finer. It also shortens the growth cycle of hair from years to months.
Side effects are commonly reported with many medications. Finasteride can cause reduced libido, erectile dysfunction, and mood changes. Post finasteride syndrome refers to the persistence of these and other symptoms such as depression, suicidal ideation, and cognitive problems after the drug has been stopped. Find out more about 'What Finasteride is and how it works'.
What symptoms are reported for post-Finasteride Syndrome?
The most commonly reported symptom in nearly all cases of PFS is persistent sexual dysfunction. But other symptoms have also been described by patients, including:
Low libido (lower sex drive)
Erectile dysfunction
Genital numbness or reduced sensitivity
Fatigue or low energy
Mood changes, including anxiety or depression
Suicidal ideation
Cognitive issues or "brain fog", including reduced concentration and decreased memory and mental performance
Insomnia
Breast tenderness or enlargement (gynaecomastia)
Muscle pain, cramps and spasms
Dry skin
Tinnitus
These symptoms will vary from person to person. Additionally, while they can occur with PFS, they may also stem from unrelated causes, such as anxiety, hormonal imbalance, or underlying medical conditions. This is partly what makes it difficult to clearly define or diagnose the syndrome.
What does the current research on post-Finasteride syndrome say?
At the moment, the scientific evidence around Post-Finasteride Syndrome is limited and mixed. Some studies suggest a potential link between Finasteride and long-term symptoms, but others do not:
PFS was first formally described in 2011. Researchers reported 71 men who experienced sexual side effects after stopping Finasteride for hair loss (3). However, these men were selected from an online forum specifically for users reporting these symptoms, so the study is not representative of the wider population.
In a 2003 double-blind, placebo-controlled study using Finasteride, the incidence of persistent sexual side effects was actually higher in the placebo group, suggesting the symptoms may not be directly related to the medication itself (4). It is possible that psychological or unrelated causes may be at play.
A 2017 study of 4,284 men (aged 16–42) who had taken Finasteride found that persistent sexual symptoms occurred in only 0.8% of users (5). The strongest predictor was use for more than 7 months, whereas another study suggests PFS is more common in younger men and may have a genetic component (6).
A long-term study that followed men over a five-year period showed that side effects with Finasteride such as reduced libido and ED only occurred in 2% of patients. The incidence of side effects was similar to placebo at one and 5 years and they disappeared in all men who stopped the drug because of side effects but also in most who continued the treatment (7).
A meta-analysis which looks at the results of many clinical trials concluded that there was a low incidence of sexual side effects and that there was also no significant difference between the incidence of side effects when comparing the drug with the placebo (8).
However, the quality of adverse event reporting in the majority of finasteride clinical trials has been brought into question by another meta-analysis which looked at the evidence from 34 different studies. They concluded that of 34 trials, none had adequate safety reporting, and there was a bias towards under-detection of side effects, with 18 studies reporting conflicts of interest and 19 receiving funding from the manufacturer. As a result of all these factors, they could not accurately establish the rate of adverse effects with the data from these 34 trials.
An example of bias in the clinical trial setting is that many of these trials have used questionnaires to report side effects, which may not be completely objective and subject to bias (for example, if the subject is reluctant or embarrassed to talk about issues such as sexual dysfunction). In addition, until recently, many clinical trials on finasteride did not use an objective, validated quantitative scale to assess side effects. In the case of erectile dysfunction (ED), they did not utilise the International Index of Erectile Function (IIEF), which provides a quantitative scale of assessment. All these factors would affect reporting of adverse effects.
The nocebo effect
It’s important to understand the role that psychological factors can play in the way a drug and its side effects are perceived. Nocebo refers to an adverse effect that is not caused by the pharmacological effect of the drug. In one study, a group of 120 men, all of whom were receiving treatment with Finasteride, were split into two equal groups. The first group received counselling about the potential side effects of the drug, the second group did not. The group that received information about the side effects reported a significantly higher proportion of sexual side effects. All the side effects were reversible on discontinuation of the medication (9).
The bottom line? The medical community is still working to understand PFS symptoms and whether Finasteride causes them directly or if other factors are involved. But for the men who experience PFS, the symptoms are very real, and it’s a risk worth considering before taking the drug.
How common is post-Finasteride syndrome?
There’s currently no definitive answer. Because PFS isn’t universally defined or officially recognised, we don’t have large-scale, population-level data on how common it is. But based on current studies, persistent, ongoing side effects appear to be rare.
Some estimates suggest around 1,000 men worldwide may be affected by PFS, most of whom are younger men. This is a small number compared to the millions of men taking Finasteride for hair loss. But for those experiencing symptoms, the impact can be significant.
Nevertheless, what we can say is that for most people, Finasteride is well-tolerated and side effects (if they occur) typically resolve after stopping the medication.
Is it possible to recover fully from post-Finasteride syndrome?
Some men have made a partial recovery but there are no reports of PFS patients returning to full health. But a handful of PFS patients have reported that they've felt 80%, 90% or even 99% better over a period of one to five years.
What can you do if you’re concerned about post-Finasteride syndrome?
If you’re currently taking Finasteride for hair loss and experiencing symptoms that worry you, don’t stop treatment abruptly or try to manage the issue alone. Talk to a healthcare professional. That could be your GP, or a contact a member of our team at Oxford Online Pharmacy.
A clinician can help you assess your symptoms, rule out other causes, and decide on the best course of action. This might involve stopping Finasteride, switching to an alternative treatment for hair loss, or exploring other potential reasons for your symptoms.
What matters most is that you don’t try to manage worrying symptoms alone, and that you feel supported in making informed choices.
Are there alternatives to Finasteride treatment?
We know that Finasteride is a very effective treatment for Male Androgenetic Alopecia (MAA) or male pattern hair loss. However, there are some other options.
Topical Minoxidil - 2% or 5%
It is thought to work by increasing the anagen (growth) phase of hair.
It may need to be applied twice daily for at least 3-4 months before the effects are realised. Continued application is needed to maintain the hair growth, otherwise, the newly grown hair may be shed within a few months. A recent study found that the 5% Minoxidil solution was superior at improving hair growth than the 2% in men with MAA (10).
These are taken as a one-a-day dose and act on the prostaglandin synthesis pathways in the hair scalp and follicles. Although used as an “off-label” therapy it has been shown to be effective in male pattern baldness (11).
Caffeine shampoos, such as Alpecin C1 Caffeine Shampoo, have shown to be a promising treatment with reported increases in hair thickness and strength.
Why it’s important to speak openly with a doctor
Whether you're considering Finasteride for the first time or have been using it for some time, open and honest conversations with a healthcare professional can make all the difference.
They can help you weigh up the benefits and risks, identify early warning signs of side effects, and make informed decisions about whether the medication is right for you. If side effects do occur, your doctor can help you manage them safely and compassionately.
At Oxford Online Pharmacy, we take every patient concern seriously. Our prescribers review each consultation carefully and are always available to answer follow-up questions. If something doesn’t feel right, we want to hear from you. You don’t need to make these decisions alone.
Reach out to your GP or contact our team for support.
Thinking about stopping? Find our what happens when you stop Finasteride.
References
Pereira AFJR, Coelho TO de A. Post-Finasteride syndrome. Anais Brasileiros de Dermatologia. 2020 May;95(3):271–7.
Healy D, Bahrick A, Bak M, Barbato A, Calabrò RS, Chubak BM, et al. Diagnostic criteria for enduring sexual dysfunction after treatment with antidepressants, Finasteride and isotretinoin. International Journal of Risk & Safety in Medicine. 2022 Feb 22;33(1):65–76.
Irwig MS, Kolukula S. Persistent Sexual Side Effects of Finasteride for Male Pattern Hair Loss. The Journal of Sexual Medicine. 2011 Jun;8(6):1747–53.
Wessells H, Roy JN, Bannow J, Grayhack JT, Matsumoto AM, Tenover L, et al. Incidence and severity of sexual adverse experiences in Finasteride and placebo-treated men with benign prostatic hyperplasia. Urology. 2003 Mar 1;61(3):579–84.
Kiguradze T, Temps WH, Yarnold PR, Cashy J, Brannigan RE, Nardone B, et al. Persistent erectile dysfunction in men exposed to the 5α-reductase inhibitors, Finasteride, or dutasteride. PeerJ. 2017 Mar 9;5:e3020.
Li X, Guo Y, Lu Y, Li H, Yan S, Li H, et al. Case report: a study of the clinical characteristics and genetic variants of post-Finasteride syndrome patients. Translational Andrology and Urology. 2022 Oct;11(10):1452–7.
Kaufman KD. Long-term (5-year) multinational experience with finasteride 1 mg in the treatment of men with androgenetic alopecia. European Journal of Dermatology. 2002;12:38–49.
Gupta AK, Charrette A. The efficacy and safety of 5α-reductase inhibitors in androgenetic alopecia: a network meta-analysis and benefit-risk assessment of finasteride and dutasteride. Journal of Dermatological Treatment. 2014 Apr;25(2):156–61. doi:10.3109/09546634.2013.813011.
Mondaini N, Gontero P, Giubilei G, Lombardi G, Cai T, Gavazzi A, et al. Finasteride 5 mg and sexual side effects: how many of these are related to a nocebo phenomenon? The Journal of Sexual Medicine. 2007. doi:10.1111/j.1743-6109.2007.00563.x.
Olsen EA, Dunlap FE, Funicella T, Koperski JA, Swinehart JM, Tschen EH, et al. A randomized clinical trial of 5% topical minoxidil versus 2% topical minoxidil and placebo in the treatment of androgenetic alopecia in men. Journal of the American Academy of Dermatology. 2002 Sep;47(3):377–85. doi:10.1067/mjd.2002.124088.
Jimenez-Cauhe J, Saceda-Corralo D, Rodrigues-Barata R, Hermosa-Gelbard A, Moreno-Arrones OM, Fernandez-Nieto D, et al. Effectiveness and safety of low-dose oral minoxidil in male androgenetic alopecia. Journal of the American Academy of Dermatology. 2019;81:648–9. doi:10.1016/j.jaad.2019.04.054.