Post-finasteride syndrome (PFS)
Post-finasteride syndrome is a term used by patients and researchers for sexual, psychological and physical symptoms that some people report persisting after they stop finasteride; the MHRA does not use the term, but does recognise that sexual side effects may persist after treatment ends.
Full definition
"Post-finasteride syndrome", often shortened to PFS, is not a formal diagnosis and does not appear in UK regulatory documents. It is the name patients and researchers use for symptoms that continue after finasteride has been stopped. What the UK regulator recognises is set out in two Drug Safety Updates. The MHRA's update of 29 April 2024 was titled, verbatim, "Finasteride: reminder of the risk psychiatric side effects and of sexual side effects (which may persist after discontinuation of treatment)". It reported that patients had described sexual dysfunction, including decreased libido and erectile dysfunction, persisting even after treatment was stopped. By 5 April 2024 the MHRA had received 426 Yellow Card reports of sexual dysfunction with finasteride, and in almost half the outcome was recorded as "not recovered" or "not resolved". The update introduced a patient alert card in every finasteride pack. The update of 11 May 2026 states that finasteride "is associated with depression, suicidal ideation and sexual dysfunction which may persist after treatment is stopped", and added a precautionary mood warning for dutasteride. The Propecia SmPC lists persistence of sexual dysfunction after stopping among post-marketing reports, and the Avodart SmPC says sexual side effects may persist after stopping dutasteride, with dutasteride's role unknown. What remains under study is the wider picture: why it happens, who is at risk, and how best to treat it. Recent reviews describe a small subgroup of patients with persistent symptoms, possible mechanisms involving the brain and genetics that are still being investigated, no clear cause or established treatment, and continuing disagreement about how to define the condition (Leliefeld 2023; Cilio 2025). If you are affected, your symptoms deserve to be taken seriously. Tell your prescriber or GP, report them on a Yellow Card (saying they continued after stopping), and read our pages on persistent sexual dysfunction, finasteride and depression and stopping finasteride safely. If you develop suicidal thoughts, contact a doctor as soon as possible, and if you have seriously harmed yourself or feel at risk of serious harm, call 999.
What it does not mean
The debate over the name and the mechanism does not mean the symptoms are imagined, exaggerated or "all in the mind": the MHRA recognises that sexual dysfunction can persist after stopping, and people living with these symptoms should be listened to. Equally, the term is not a formal diagnosis, it does not mean that every symptom after stopping finasteride was caused by it, and it does not mean that most people who take finasteride will develop persistent symptoms; the MHRA describes persistence "in some cases".
UK regulatory source
MHRA Drug Safety Update, Finasteride: reminder of the risk of psychiatric side effects and of sexual side effects (which may persist after discontinuation of treatment), 29 April 2024; MHRA Drug Safety Update, Finasteride and dutasteride: updated safety warnings for psychiatric side effects and sexual dysfunction, 11 May 2026; Propecia 1 mg and Avodart 0.5 mg SmPCs section 4.8; Leliefeld HHJ et al. Int J Impot Res 2025 (PMID 37697052); Cilio S et al. Int J Impot Res 2025 (PMID 39953145)