Estradiol for PFS: what is known so far

Read that estradiol, a form of oestrogen, might help post-finasteride syndrome (PFS)? It’s a theory. We found no published study of estradiol in people with PFS, and there is no approved treatment for PFS.

The UK Propecia leaflet says erection problems can last after stopping finasteride. The estradiol idea grew from two small studies of skin samples, and nobody has taken the next step of testing it as a treatment.

So what did those studies find?

Where does the estradiol idea come from?

It comes from the androgen receptor. That’s the switch in a cell that testosterone and DHT, its stronger form, turn on. Some researchers have proposed that after finasteride these switches become more numerous or more sensitive.

Two small studies looked for this in penile skin. An Italian study compared foreskin from eight men with lasting sexual problems after finasteride with foreskin from eleven men who’d never taken it. More cells carried the receptor in the men with PFS. A US study of 26 men with PFS also found higher activity of the receptor’s gene in penile skin.

Estradiol enters here as a way to turn testosterone down. In men, it tells the brain to send less of the signal that makes the testes produce testosterone. Less testosterone, the theory goes, would mean less stimulation of oversensitive receptors.

Both skin studies were small, took samples only after the symptoms began, and couldn’t show cause and effect. The US authors list that themselves. Our article on androgen receptor genes in PFS covers a related line of research.

Has anyone tested estradiol in PFS?

No. We found no published trial, case series or case report of estradiol given for PFS.

The research reviews say the same about PFS treatment in general. A 2020 review in Fertility and Sterility found “no evidence-based effective treatments for PFS”. A 2023 review describes PFS as a condition “without a clear etiology or therapy”.

The theory has gaps of its own. A Harvard study found that men with lasting symptoms after finasteride had normal testosterone and DHT in their blood. And PFS is more than sexual problems: the 2022 diagnostic criteria say it can bring problems with cognition, depression and suicidality, sometimes without any sexual difficulties. A receptor finding in penile skin doesn’t explain those.

Researchers have looked beyond hormones in the blood. In this short talk, Dr Michael Irwig describes his 2011 study of men with lasting sexual side effects. From about 3:36 he asks whether the problem lies in hormones in the brain. It’s background on why the cause is still open, not evidence about estradiol.

Play video: Persistent sexual side effects of finasteride (Propecia) for male pattern hair loss

What is known about estradiol’s side effects in men?

Most of what we know comes from men with prostate cancer, who took it to lower testosterone on purpose. In the UK PATCH trial, estradiol patches brought testosterone down about as well as the standard hormone injections. Breast growth affected about 9 in 10 men on estradiol patches, against about 4 in 10 on the standard injections.

Oestrogen tablets were once used for prostate cancer, but they caused heart and blood vessel problems, the PATCH researchers note. Their patches were designed to avoid that, and heart problems were no more common than with the standard injections.

Those results come from men with cancer, under close hospital follow-up. They don’t tell us what estradiol would do to a younger man with PFS. The Propecia leaflet already lists breast swelling and tenderness as possible finasteride side effects.

What can I do?

There is no approved treatment for PFS, and estradiol isn’t one. Hormone medicines bought online, without a doctor, may not contain what the label says.

If you’re still taking finasteride, that’s a decision for you and your prescriber. The leaflet says to stop and contact a doctor if your mood changes.

A GP or specialist can still look at each symptom you have, and rule out other causes. Our guides on how to talk to your doctor about PFS and PFS blood tests can help you prepare. Keep a dated record of your symptoms, so you can see what changes over time.

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. Our guides cover Yellow Card and the FDA step by step.
• 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?

Is PFS caused by too much testosterone? Nobody knows. The Harvard study found normal testosterone and DHT in the blood of men with lasting symptoms. The receptor findings come from skin samples in two small studies, and they don’t show what causes PFS.

Do regulators recognise lasting symptoms? Yes. In May 2026 the UK regulator said finasteride “is associated with depression, suicidal ideation and sexual dysfunction which may persist after treatment is stopped”.

Where can I hear what others have tried? Our WhatsApp peer support groups bring people with PFS together. Treat what you hear as one person’s experience. It isn’t evidence that something works.

If you have lasting symptoms after finasteride, a Yellow Card report adds you to the record researchers and regulators use. Our PFS page is a good place to start.

Sources

1. Propecia 1 mg Film-coated Tablets, patient leaflet, Organon, Electronic Medicines Compendium. Section 4, frequency unknown: “persistent difficulty having an erection after discontinuation of treatment”; breast swelling or tenderness. Section 2: stop and contact your doctor if mood changes.
2. Di Loreto C, La Marra F, Mazzon G and colleagues. Immunohistochemical evaluation of androgen receptor and nerve structure density in human prepuce from patients with persistent sexual side effects after finasteride use for androgenetic alopecia. PLoS One 2014;9(6):e100237. Retrospective case-control; 8 cases, 11 controls; nuclear androgen receptor in stromal cells 40% against 23% of cells.
3. Howell S, Song W, Pastuszak A, Khera M. Differential gene expression in post-finasteride syndrome patients. J Sex Med 2021;18(9):1479-90. 26 cases, 26 controls; androgen receptor expression higher in penile skin; limitations include selection bias, no samples before exposure and “a lack of mechanistic data to imply causality”.
4. Langley RE, Gilbert DC, Duong T and colleagues. Transdermal oestradiol for androgen suppression in prostate cancer: long-term cardiovascular outcomes from the randomised PATCH trial programme. Lancet 2021;397(10274):581-91. 1,694 men; castration rates at 3 months 93% in both arms; gynaecomastia 86% on patches against 38% on LHRH agonists; no difference in time to first cardiovascular event; background on cardiovascular toxicity of oral oestrogen.
5. Basaria S, Jasuja R, Huang G and colleagues. Characteristics of men who report persistent sexual symptoms after finasteride use for hair loss. J Clin Endocrinol Metab 2016;101(12):4669-80. Testosterone and DHT did not differ from controls and were within normal ranges.
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 can also bring cognitive problems, depression and suicidality, which can occur without sexual dysfunction.
7. Traish AM. Post-finasteride syndrome: a surmountable challenge for clinicians. Fertil Steril 2020;113(1):21-50. “To date, there are no evidence-based effective treatments for PFS.”
8. Leliefeld HHJ, Debruyne FMJ, Reisman Y. The post-finasteride syndrome: possible etiological mechanisms and symptoms. Int J Impot Res 2025;37(6):414-21, online September 2023.
9. MHRA, Finasteride and dutasteride: updated safety warnings for psychiatric side effects and sexual dysfunction, Drug Safety Update, 11 May 2026.
10. GOV.UK. Report a problem with a medicine or medical device.
11. PFS Foundation, Persistent sexual side effects of finasteride (Propecia) for male pattern hair loss, August 2012. Dr Michael Irwig. Background, not evidence about estradiol.