Worried about PFS? What to know

We found no test that can tell you in advance whether finasteride will leave you with post-finasteride syndrome (PFS). The UK leaflet warns that some sexual side effects have continued after stopping, and that lasting pattern is what patients call PFS.

PFS is more than sexual problems. The diagnostic criteria proposed in 2022 say problems with thinking, depression and suicidality can occur with or without sexual difficulties.

A hair-loss forum rule Miles (below) read said if you had no side effects in the first 72 hours, you never would. The official documents give no such rule, only a short list of signs to watch for.

Miles was 23 and losing his hair when he decided to try finasteride. Before his first tablet, he did a lot of research. Watch the extract for what that research told him.

Play video: Miles on the research he did before finasteride (Moral Medicine, extract)

“I was super scared,” he says. Online he kept hearing that the chance was “less than one percent”, and that side effects “always go away”. He was fine “for a year and a half”. Then erection problems began, at 25, and later the emotional numbness that many people with PFS describe.

Will I get PFS from finasteride?

We found no way to know in advance. In October 2026 we searched PubMed and the regulator’s latest review, and found no test or study that picks out who is at risk before the first tablet.

The MHRA, the UK medicines regulator, reviewed the research in 2024. Some studies suggested that people with a personal or family history of mental illness were more likely to get side effects. The regulator says those studies had real limits, and that everyone should be monitored “regardless of their clinical or family history”.

One large study found that time on the drug mattered. Researchers at Northwestern University in Chicago went through the medical records of young men on the hair-loss dose. About 8 in 1,000 had erection problems that lasted at least three months after stopping, and the risk was higher in men who’d taken it for longer.

That study counted one symptom, and only when it was written in a medical record. We found no study that has counted how often PFS as a whole happens.

Do finasteride side effects go away?

For most men in the trials, yes. In the trials behind the US label, about 4 in 100 men on finasteride reported sexual side effects, against about 2 in 100 on a dummy pill. They cleared in the men who stopped because of them, and in most of those who carried on.

The UK leaflet says some side effects “disappeared when treatment is stopped”. It then lists three that didn’t, including “persistent difficulty having an erection after discontinuation of treatment”. Next to each one it says “Frequency unknown”, which means the leaflet can’t say how often it happens.

For some people it has lasted years after stopping. We found no study that predicts who will be affected, or whether it will ease. Our page on stopping finasteride covers what happens to your hair and to side effects.

Can finasteride cause anxiety or depression?

Yes, says the UK leaflet. It lists anxiety, depression and suicidal thoughts among the possible side effects. The MHRA says anxiety was added to the product information in 2017.

Marshall took finasteride for five years with no problems. Then, he says, it “flipped on like a light switch”: panic attacks so strong he thought he was having heart attacks. Hospital tests found nothing wrong with his heart, and at first he didn’t link it to the tablets. The extract is worth a minute because it shows how easily a first sign can look like something else.

Play video: Marshall on his first symptoms after five years of finasteride (Moral Medicine, extract)

Later in the same interview, asked about his recovery, he says he feels fully well most of the time.

On 11 May 2026 the MHRA told doctors to give patients this advice for the 1 mg hair-loss dose: “stop finasteride 1mg immediately if you develop depression or suicidal thoughts and contact your doctor as soon as possible”. It also asks you to tell your doctor if you’ve ever had depression or suicidal thoughts.

If you’re struggling right now, the Samaritans are free to call on 116 123 (UK and Ireland), day or night.

What can I do?

Finasteride helps many men keep their hair. Whether it’s right for you is a decision for you and your prescriber.

Know the signs. The leaflet’s list is short: less interest in sex, trouble getting an erection, problems with ejaculation, low mood, and any lump or pain in the breast. It asks you to “make a note of what happened, when it started and how long it lasted”. For example: “Finasteride 1 mg from March 2025. Lower sex drive since June.”

Many people say it took time to be taken seriously, so bring the leaflet line. Our guide on which doctor to see about PFS can help.

Report it: it helps everyone

A doctor’s note helps you. A report to the medicines regulator helps everyone else: it is how patterns get noticed.

• No proof needed. A suspicion is enough, even years after stopping.
• Where: the Yellow Card scheme in the UK, MedWatch in the US.
• Use the right words. If symptoms continued after stopping, write Post 5-alpha-reductase inhibitor syndrome (MedDRA 10082430).

Our reporting guide walks you through it

What else do people ask?

Am I safe if I’ve had no side effects for months? Neither the leaflet nor the MHRA names a point after which you’re in the clear. Reports to the UK regulator include side effects that began after years of use (MHRA review), and Miles was fine for a year and a half. Our page on when finasteride side effects start has the details.

Can PFS happen after a few pills? Some people say their symptoms began after a few tablets, though most reports describe longer use. Our article on PFS after a few pills looks at those reports and the people behind them.

Is there a test for PFS? No. The authors of the 2022 diagnostic criteria note that there is no biomarker for it, so their criteria rest on what changed, and whether it lasted at least three months after stopping, with other causes ruled out. Our page on post-finasteride syndrome explains what is known.

Miles did his research and kept hearing that side effects always go away. Read the leaflet’s full list of signs, and if something changes and stays, report it.

Sources

1. Propecia 1 mg film-coated tablets: patient information leaflet, last revised May 2026, electronic medicines compendium (emc). Section 2: mood alterations and depression. Section 4: some side effects “disappeared when treatment is stopped”. Under “Frequency unknown”: persistent erection, sex drive and ejaculation problems after discontinuation, anxiety, suicidal thoughts. Also: “make a note of what happened, when it started and how long it lasted”.
2. Propecia (finasteride), US prescribing information, revised August 2022, DailyMed. Section 6.1: in the integrated analysis, 36 of 945 men on finasteride (3.8%) and 20 of 934 on placebo (2.1%) reported sexual adverse experiences. “Resolution occurred in men who discontinued therapy with PROPECIA due to these side effects and in most of those who continued therapy.” Section 6.2: sexual dysfunction that continued after discontinuation.
3. MHRA, Finasteride and dutasteride: updated safety warnings for psychiatric side effects and sexual dysfunction, Drug Safety Update volume 19, issue 10, 11 May 2026. Advice for healthcare professionals to provide to patients; patient cards in the 1 mg and 5 mg packs.
4. MHRA, Finasteride: review of safety data and expert advice on management of risks, public assessment report, April 2024. Anxiety added to the product information in 2017. The evidence on lasting psychiatric and sexual side effects is “mixed”. Yellow Card reports: time to onset from 1 day to 5,923 days. Section “Effect in different risk groups”: personal or family history of a psychiatric disorder, with limitations; monitoring “regardless of their clinical or family history”.
5. Kiguradze T, Temps WH, Yarnold PR and colleagues. Persistent erectile dysfunction in men exposed to the 5α-reductase inhibitors, finasteride, or dutasteride. PeerJ 2017;5:e3020. Northwestern Medicine records. Men aged 16 to 42 on finasteride 1.25 mg a day or less: 34 of 4,284 (0.8%) had erectile dysfunction lasting at least 90 days after stopping; longer exposure was the strongest predictor; median persistence 1,534 days.
6. Healy D, Bahrick A, Bak M and colleagues. Diagnostic criteria for enduring sexual dysfunction after treatment with antidepressants, finasteride and isotretinoin. Int J Risk Saf Med 2022;33(1):65-76. Proposed criteria. Section 5: finasteride effects that can occur independently of any sexual difficulties (cognitive impairment, depression, suicidality). “In the absence of a biomarker”; problem present for at least 3 months after stopping; other causes excluded.
7. Moral Medicine, Post Finasteride Syndrome: Man Didn’t Believe It Could Happen to Him, interview with Miles, 19 June 2023. Starting at 23 from 1:53; the forum line about 72 hours at 3:46; “a lot of research” at 27:02. “Less than one percent” at 3:26 and 27:13; “I was super scared” at 27:04; “always go away” at 27:16. Erection problems at 25 from 4:48; “for a year and a half” at 28:32. Extract played: 27:02 to 28:37.
8. Moral Medicine, Man Takes Finasteride for 5 Years Before Developing PFS, interview with Marshall, 3 July 2024. Five years before the first symptoms at 3:51; “flipped on like a light switch” at 4:03; heart tests from 4:27; feeling “100%” most of the time, asked about his recovery, at 13:33. Extract played: 3:57 to 5:15.