What is Post-Finasteride Syndrome?

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.

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.

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.  

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).

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.

What does the current research 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).

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. 

What symptoms are reported?

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
• Fatigue or low energy
• Mood changes, including anxiety or depression
• Cognitive issues or "brain fog"
• Genital numbness or reduced sensitivity

Some reports also mention sleep disturbances, dry skin, and breast tenderness or enlargement.

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.

How common is it?

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. 

What can you do if you’re concerned?

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 member of our clinical 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.

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.

References

1. Pereira AFJR, Coelho TO de A. Post-Finasteride syndrome. Anais Brasileiros de Dermatologia. 2020 May;95(3):271–7.
2. 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.
3. 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.
4. ‌Wessells H, Jitendra Nath Roy, 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.
5. 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:e3020–0.
6. ‌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 [Internet]. 2022 Oct;11(10):1452–7.