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Side effects Finasteride

Finasteride side effects in the UK: what the MHRA says

Short answer

The side effects people report most often are sexual: problems getting an erection, less interest in sex and changes in ejaculation. The MHRA also warns that finasteride is associated with depression, suicidal thoughts and sexual dysfunction that may persist after treatment is stopped. If you develop depression or suicidal thoughts on finasteride 1 mg, stop it and contact your doctor straight away.

Plain white tablets spilling from an unlabelled white bottle on a green background

Key facts

  • Finasteride 1 mg is licensed in the UK for men with male pattern hair loss. It is not licensed for women.
  • The UK patient leaflet lists erection problems, less desire for sex and ejaculation problems as uncommon (up to 1 in 100 people). The NHS groups the first two under common side effects. Sources differ on the band, and both agree these are the effects most often reported.
  • The MHRA issued Drug Safety Updates on 29 April 2024 and 11 May 2026. A patient alert card now comes in every pack.
  • Mood effects (depression, anxiety, suicidal thoughts) and persistent sexual problems are the two warnings the MHRA asks both prescribers and patients to take seriously.
  • Breast changes, an allergic reaction or a mood change are not things to wait out. Each has its own action below.

Go straight to the guide for your concern

Sexual side effects that last after stopping What the MHRA recognises, what the figures mean, and who to see. Finasteride and depression Low mood on treatment: what to look for and what to do. Finasteride and suicidal thoughts What to do today if you are having these thoughts. Finasteride and brain fog Concentration and clarity problems, and how they are reported. Finasteride and breast changes Tenderness, swelling or a lump, and when to see a GP. Finasteride sexual side effects: how common? Trial figures, how sources differ, resolution and persistence. The finasteride patient alert card What the card in the pack says and what to do with it. MHRA safety updates, in date order Every regulator update on these medicines, with sources. Finasteride MHRA warnings: 2024 and 2026 What changed between the two Drug Safety Updates.

What the MHRA has said

The MHRA is the UK medicines regulator. It has published two Drug Safety Updates on finasteride.

29 April 2024. After a safety review, the MHRA reminded prescribers that finasteride is associated with depression, suicidal thoughts and sexual dysfunction, and said that "in some cases sexual dysfunction has persisted in patients even after they have stopped taking finasteride". It asked prescribers to check for a history of depression or suicidal ideation before prescribing and to monitor for psychiatric and sexual side effects, and it announced a patient alert card for every finasteride pack. It quoted Yellow Card reports up to 5 April 2024: 426 reports of sexual dysfunction since November 1992, almost half recorded as "not recovered" or "not resolved".

11 May 2026. The MHRA updated the warnings after reviewing the scientific literature, Yellow Card reports and the actions of other regulators. Prescribers should tell patients about the risks when prescribing and point them to the patient card and leaflet. The finasteride 1 mg product information is being updated to say that sexual dysfunction may contribute to mood disorders, and that sexual dysfunction has also been reported without mood changes. The Yellow Card data for 1994 to 31 May 2025 included 170 reports of suicidal ideation and related terms for finasteride (1 mg and 5 mg), 19 of them fatal.

These are two different Yellow Card datasets covering different dates and different effects, so the figures should not be added together or compared. The MHRA is clear that a reported reaction does not necessarily mean the medicine caused it. Our MHRA tracker sets out each update in order, and the news article on what changed between 2024 and 2026 explains the difference in plain English.

Sexual side effects

These are the best known. The Propecia (finasteride 1 mg) patient leaflet lists three as uncommon, meaning they may affect up to 1 in 100 people: being unable to have an erection, less desire to have sex, and problems with ejaculation. The product information adds decreased semen volume. The NHS lists problems getting an erection, less interest in sex and ejaculation problems such as little or no semen as common, and says they "usually improve after a while, but they can sometimes carry on even after you stop taking finasteride".

Two things follow. First, sexual side effects are a reason to talk to your prescriber early rather than wait; the MHRA's advice to patients is to contact your doctor about reduced sex drive, erection difficulties or ejaculation problems. Second, the persistent case is real but poorly understood. Our guide to sexual side effects that persist after stopping covers what the regulator recognises, and the post-finasteride syndrome glossary entry explains the term patients use. Dysfunction can also feed into low mood, which is why the 2026 update links the two.

Mood: depression, anxiety and suicidal thoughts

The Propecia product information lists depression as uncommon, and anxiety and suicidal ideation as "not known", which means the frequency cannot be estimated from the available data. The patient leaflet tells you to stop taking Propecia and talk to your doctor if you develop depression or suicidal thoughts. The NHS gives the same instruction: if you take finasteride for hair loss and notice low mood, "stop taking the medicine straight away".

The MHRA also asks friends and family to watch for changes in mood or behaviour, because you may not notice them yourself. Tell your prescriber before you start if you have ever had depression or suicidal thoughts. That is not an automatic bar, but it changes the conversation.

If you are having thoughts of harming yourself, get help now. Call Samaritans free on 116 123 at any time, call NHS 111, or call 999 or go to A&E if you feel at serious risk. Do not drive yourself. Then tell your prescriber. Our guides to finasteride and depression and finasteride and suicidal thoughts go into more detail. "Brain fog" is not a named effect in the Propecia product information, but people do report it, and our brain fog guide explains how to describe it to a doctor.

Breast changes

Breast tenderness and enlargement are listed in the Propecia product information with a frequency of "not known". Breast cancer in men has also been reported after the tablet came on the market, and the product information asks doctors to tell patients to report any change in breast tissue promptly. The NHS lists a lump, pain or swelling in the chest, or discharge from a nipple, as a reason to get it checked by a doctor or NHS 111.

Most breast changes in men have other causes and are not cancer, but you cannot tell that yourself. If you notice a change, see your GP or tell your prescriber. Our breast changes guide explains what to expect.

Other effects listed in the product information

All of these are listed with a frequency of "not known" in the Propecia product information:

Allergic reaction. Rash, itching, hives, or swelling of the lips, tongue, throat or face. Stop taking the tablet and contact your doctor immediately. Sudden swelling of the mouth or throat, trouble breathing or swallowing, or fainting is an emergency: call 999.

Other effects. Palpitations, raised liver enzymes (seen on a blood test), pain in the testicles, blood in the semen, and male infertility. Our guide to finasteride and trying for a baby covers fertility.

The leaflet is the full list. The NHS page notes that it shows only some effects and points to the leaflet inside the pack.

Before you start, and while you take it

Before starting: read the patient card and leaflet in the pack, and tell the prescriber about any history of depression or suicidal thoughts. The MHRA asks prescribers to check your record and to review you regularly for psychiatric and sexual side effects, so expect those questions at follow-up.

While taking it: finasteride lowers PSA, a blood marker used to check the prostate, so tell anyone who orders a PSA test that you take it. The product information says that doubling the PSA level should be considered before a result is evaluated; see finasteride and the PSA test. Women who are or may be pregnant should not handle crushed or broken tablets. Finasteride is not licensed for women; see can women take finasteride.

Side effects are not the only question. The long-run picture is in is finasteride safe long term, and the other everyday questions are in alcohol and what to do about a missed dose.

What to do if you notice a side effect

Mood change, depression or suicidal thoughts on finasteride 1 mg: stop the tablet and contact your doctor as soon as possible. This is the MHRA's advice, and the leaflet says the same. If you feel at risk, use Samaritans (116 123), NHS 111 or 999 first.

Sexual side effects: contact your prescriber, who can talk through whether to continue, and see your GP if they do not settle. Stopping is always a valid choice, and our guide to stopping finasteride explains what to expect.

Breast lump, pain, swelling or nipple discharge: tell your prescriber and see your GP promptly.

Allergic reaction: stop and get help, as above.

Report it. You, as a patient, can report a suspected side effect to the MHRA through the Yellow Card scheme. Reports help the regulator's ongoing review, and our Yellow Card glossary entry explains how it works.

Licence status and how we prescribe

Finasteride 1 mg tablets are licensed in the UK for men with male pattern hair loss, to increase hair growth and prevent further hair loss. The licensed dose is one 1 mg tablet daily.

The finasteride and minoxidil topical that WMG Meds can prescribe is different: it is an unlicensed special, prescribed off-label after an individual assessment, and it has no product information of its own. The MHRA warnings above are what we explain to patients for both. A GMC-registered doctor reviews your history, covers the risks and the patient card before anything is prescribed, and reviews how you are getting on at follow-up. See the finasteride 1 mg and finasteride and minoxidil topical pages, and topical versus oral finasteride. Whether finasteride is right for you is a decision for you and your doctor, and "not for me" is a reasonable answer.

Noticed something, or weighing it up?

If you are taking finasteride and have noticed a change, a GMC-registered doctor can review it with you, including if your medicine came from another provider. If you are deciding whether to start, the doctor will go through these risks with you first.

Start a clinical review → Report via MHRA Yellow Card

Related questions

What are the most common side effects of finasteride?

Sexual ones: problems getting an erection, less interest in sex and ejaculation changes such as less semen. The Propecia leaflet lists them as uncommon (up to 1 in 100 people) and the NHS lists them as common, so the exact band depends on the source. Most people who take finasteride do not report them.

Do finasteride side effects go away after stopping?

Often they improve, but not always. The NHS says sexual side effects "usually improve after a while, but they can sometimes carry on even after you stop taking finasteride", and the MHRA says sexual dysfunction may persist after treatment is stopped. There is no test that predicts who will be affected. See our guide to persistent sexual side effects.

Can finasteride cause depression?

Yes. Depression is listed in the UK product information, and the MHRA says finasteride is associated with depression and suicidal ideation. If you develop either on finasteride 1 mg, stop it and contact your doctor as soon as possible. If you are struggling now, call Samaritans free on 116 123.

What is the finasteride patient alert card?

A card in the pack that reminds you of the psychiatric and sexual side effects. The MHRA announced it in April 2024 and the product information says it is provided with the package. Read it before you start and keep it with the leaflet.

Can I take finasteride if I have had depression?

That is a decision for you and a doctor. The MHRA asks prescribers to ask about any history of depression or suicidal ideation before prescribing, so tell the prescriber honestly. It does not need to rule treatment out, but it changes how closely you are reviewed and how you are advised to act on a change in mood.

How do I report a finasteride side effect?

Through the MHRA Yellow Card scheme at yellowcard.mhra.gov.uk. Patients, carers and healthcare professionals can all report a suspected side effect. Also tell your prescriber, who can review your treatment.

Sources

Facts checked against these sources on 22 October 2026. This page is general information, not personal medical advice. Read our editorial policy.

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All side-effect guides →

Worried about a symptom?

Speak to a GMC-registered doctor about it

If you are experiencing this on treatment, it should be reviewed rather than guessed at. Our clinicians assess symptoms against your full history and adjust, switch or stop treatment as appropriate. If you are on medication from another provider, we can still review you.

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If you are having thoughts of harming yourself, do not wait for a review. Contact your GP, call 111, or call the Samaritans free on 116 123 at any time. In an emergency call 999.