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Side effects Dutasteride

Dutasteride side effects: UK guide and MHRA advice

Short answer

The UK leaflet lists erection problems, lower sex drive, ejaculation problems and breast enlargement or tenderness as common, and says the sexual ones may continue after you stop. In May 2026 the MHRA added a precautionary warning about depressed mood and suicidal thoughts, because they have been reported with a related medicine. Dutasteride is licensed for an enlarged prostate, so its use for hair loss is off-label.

Plain white capsules on a green background

Key facts

  • Dutasteride is licensed in the UK to treat an enlarged prostate. Using it for hair loss is off-label, and it is for men only.
  • The patient leaflet lists impotence, decreased sex drive, ejaculation difficulty and breast enlargement or tenderness as common (up to 1 in 10 men).
  • The product information says sexual side effects "may persist after treatment discontinuation" and that the role of dutasteride in this persistence is unknown.
  • On 11 May 2026 the MHRA added a precautionary mood warning to the product information. The data for dutasteride itself are very limited.
  • The side-effect figures come from men treated for prostate problems, not hair loss, so they may not translate exactly.

Go straight to the guide for your question

Dutasteride and sexual side effects Trial figures, the persistence warning and what to do. How to stop dutasteride safely The long half-life, and what to expect after stopping. Dutasteride and CYP3A4 inhibitors Medicines that can raise dutasteride levels. Is dutasteride licensed for hair loss? The licence, off-label prescribing and what it means. Can you donate blood on dutasteride? The six-month rule after the last dose. MHRA safety updates, in date order Every regulator update on these medicines, with sources.

Licence status, and what the figures are based on

In the UK, dutasteride (Avodart and generic versions) is licensed to treat men with an enlarged prostate (benign prostatic hyperplasia). Hair loss is not a licensed use, so a doctor who prescribes it for hair loss is prescribing off-label, meaning outside the licence. The prescriber takes responsibility and must explain the off-label use and the known risks before you decide. Our guide to whether dutasteride is licensed for hair loss covers this.

The side-effect information below comes from the Avodart product information, which is based mainly on older men treated for prostate problems, some also taking tamsulosin. Men taking it for hair loss are usually younger and are not using it for the same reason, so the figures are a guide rather than a forecast. The capsule is 0.5 mg and must be swallowed whole; it is for men only and must not be taken by women, children or adolescents.

Common side effects listed in the leaflet

The Avodart patient leaflet lists these as common, meaning they may affect up to 1 in 10 men:

Not being able to achieve or maintain an erection (impotence). The leaflet says this may continue after you stop taking Avodart.

Decreased sex drive (libido). This may also continue after you stop.

Difficulty with ejaculation, such as a decrease in the amount of semen released. This may also continue after you stop.

Breast enlargement or tenderness (gynaecomastia).

Dizziness when taken with tamsulosin.

Uncommon (up to 1 in 100 men): heart failure, and hair loss (usually from the body) or hair growth. Frequency not known: depression, and pain and swelling in the testicles. The leaflet is the full list.

Sexual side effects and persistence

Sexual side effects are the best documented. The SmPC, the official prescribing information, states: "These sexual adverse events may persist after treatment discontinuation. The role of dutasteride in this persistence is unknown." In plain terms: for some men the effects do not go away straight after stopping, the product information does not say how often, and nobody can yet predict who will be affected.

If you notice a change in desire, erections or ejaculation, tell your prescriber early rather than waiting. The MHRA's advice to patients is to contact your doctor about sexual side effects. Our guide to dutasteride and sexual side effects sets out the trial figures and what to do, and the NHS lists many other causes of erection problems, so a GP can help look at the whole picture.

Mood: the MHRA precautionary warning

On 11 May 2026 the MHRA published updated safety warnings for finasteride and dutasteride. Because dutasteride works in the same way as finasteride, the MHRA said that "as a precaution" a warning would be added to the dutasteride product information that depressed mood, depression or suicidal ideation has been reported with another medicine in the same class. It stressed that the data for dutasteride itself are very limited.

The Avodart leaflet now says that if any mood symptoms occur you should contact your doctor for advice as soon as possible. It also lists depression with a frequency of "not known". The MHRA's Yellow Card figures for dutasteride 0.5 mg, from 1994 to 31 May 2025, include 5 reports of suicidal ideation and related terms, none fatal. The MHRA is clear that a reported reaction does not necessarily mean the medicine caused it.

If you have low mood or 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. Then contact your prescriber. Tell your prescriber before you start if you have ever had depression or suicidal thoughts.

Breast changes, the prostate and PSA

Breast changes. The leaflet says dutasteride may cause breast enlargement and tenderness, and that if this becomes troublesome, or you notice breast lumps or nipple discharge, you should talk to your doctor, as these may be signs of a serious condition such as breast cancer. The SmPC reports male breast cancer rarely. Do not wait and see: tell your prescriber and see your GP.

PSA. Dutasteride lowers the PSA blood test, used to check the prostate, by about 50% after 6 months. Tell any doctor who orders a PSA test that you take it.

Prostate cancer. The leaflet says that in a clinical study of men at increased risk of prostate cancer, men taking Avodart had a serious form of prostate cancer more often than men who did not, and that the effect of Avodart on this is not clear. This was a study in men at higher risk of prostate cancer, not men taking it for hair loss.

Fertility, pregnancy and handling

Dutasteride has been found in the semen of men taking it, and the leaflet says to use a condom if your partner is or may be pregnant, because it may affect the normal development of a male baby. It has been shown to reduce sperm count, semen volume and sperm movement, so male fertility may be reduced.

Women who are pregnant or may be pregnant must not handle leaking capsules, as dutasteride is absorbed through the skin. If a woman touches a leaking capsule, she should wash the area immediately with soap and water, and the leaflet advises contacting a doctor if a pregnant woman has come into contact with it.

It stays in the body for a long time

The SmPC gives dutasteride a half-life of about 3 to 5 weeks at therapeutic levels, which is why it takes months to clear. That matters for side effects: a problem may not ease the week you stop. Our guide to stopping dutasteride explains the timeline, and the blood donation question covers the six-month rule.

What to do if you notice a side effect

Mood change or thoughts of suicide: contact your prescriber or GP as soon as possible, and use Samaritans (116 123), NHS 111 or 999 if you feel at risk.

Sexual side effects or breast changes: contact your prescriber, and see your GP for a breast lump or discharge. Stopping is always a valid choice.

Allergic reaction (itchy rash, hives, swelling of the eyelids, face, lips, arms or legs): the leaflet says to stop and contact your doctor immediately.

Report it. Patients can report a suspected side effect through the MHRA Yellow Card scheme. Reports help the regulator's ongoing review.

How we prescribe it

At WMG Meds, a GMC-registered doctor reviews your assessment, history and medicines before dutasteride is considered. If it is appropriate, the doctor explains the off-label use, the MHRA advice, the handling precautions and the persistence warning before any prescription, and reviews you at follow-up. Whether to start is your decision, and "not for me" is a reasonable answer. Our news guide to dutasteride for hair loss and the dutasteride product page describe the process.

Noticed something, or weighing it up?

If you take dutasteride 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 dutasteride?

The Avodart leaflet lists impotence, decreased sex drive, difficulty with ejaculation and breast enlargement or tenderness as common, affecting up to 1 in 10 men. These figures come from men treated for an enlarged prostate.

Can dutasteride side effects be permanent?

The product information says the sexual side effects may persist after you stop, and that the role of dutasteride in this persistence is unknown. It does not say how often. If effects do not settle, tell your prescriber and your GP and report them through Yellow Card.

Does dutasteride cause depression?

Depression is listed with a frequency of "not known", and the MHRA added a precautionary warning in May 2026 because depressed mood and suicidal thoughts have been reported with a related medicine. The MHRA said data for dutasteride are very limited. Contact your doctor promptly if your mood changes, and call Samaritans free on 116 123 if you are struggling.

Is dutasteride licensed for hair loss in the UK?

No. It is licensed for an enlarged prostate. Prescribing it for hair loss is off-label, which your prescriber must explain to you.

How long do dutasteride side effects last after stopping?

There is no fixed answer. The half-life is about 3 to 5 weeks, so the medicine takes months to clear, and the product information says sexual side effects may persist. Speak to your prescriber about your own situation.

Can women handle dutasteride capsules?

Women who are or may be pregnant must not handle leaking capsules, because dutasteride is absorbed through the skin. The medicine must not be taken by women, children or adolescents. Wash any contact area with soap and water straight away.

Sources

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

Keep reading

Male pattern hair loss Condition guide Is dutasteride licensed for hair loss in the UK? Question answered Can you donate blood while taking dutasteride? Question answered Can you buy dutasteride without a prescription in the UK? Question answered Dutasteride and sexual side effects Side effect guide Stopping Dutasteride 0.5 mg Safe discontinuation guide Dutasteride 0.5 mg capsules Medicine information Off-label prescribing Glossary Half-life (drug half-life) Glossary MHRA Yellow Card scheme Glossary Dutasteride for hair loss in the UK: a patient guide News and guides Dutasteride and CYP3A4 inhibitors Interaction guide

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.