If you are in crisis: Samaritans 116 123 (free, 24/7), text SHOUT to 85258, NHS 111, or attend your nearest A&E.
What the regulator says
The Avodart 0.5 mg SmPC reports, from the enlarged-prostate trials, drug-related impotence in 6.0% of men during the first year of treatment (1.7% during the second year), altered (decreased) libido in 3.7% (0.6%) and ejaculation disorders in 1.8% (0.5%). It states: 'These sexual adverse events are associated with dutasteride treatment (including monotherapy and combination with tamsulosin). These adverse events may persist after treatment discontinuation. The role of dutasteride in this persistence is unknown.' The MHRA Drug Safety Update of 11 May 2026 added a precautionary warning for dutasteride, because mood changes have been reported with finasteride; data for dutasteride were very limited.
In plain English
Dutasteride is licensed in the UK for an enlarged prostate (benign prostatic hyperplasia) and is prescribed off-label for hair loss. It blocks both forms (type 1 and type 2) of the 5-alpha-reductase enzyme, lowering serum DHT by a median of 94% at one year in the prostate trials. Sexual side effects are its best-documented side effects.
The figures above come from older men treated for prostate enlargement, not younger men treated for hair loss, so they may not translate exactly. They do show a pattern: most reports came in the first year, with fewer new reports later. In the four-year CombAT trial, men taking dutasteride alone reported impotence at 5.1% in year one, falling to 0.3% in year four.
The harder question is whether symptoms can continue after stopping. The SmPC says they may persist, but that dutasteride's role in this persistence is unknown. Dutasteride also has a long half-life of about 3 to 5 weeks, so it stays in the body for months after the last capsule.
How long does it last
In the trials, most sexual side effects were reported early in treatment, with fewer new reports in later years. Because dutasteride clears slowly, the medicine is still present for months after stopping. The SmPC acknowledges that sexual side effects may persist after stopping, and there is no test that predicts who will be affected or how long recovery will take. Evidence on persistence after dutasteride specifically is limited.
What to do if it happens to you
Talk to your prescriber early. You do not need to wait and see. Note what changed (desire, erections or ejaculation), when it started and how much it bothers you. Your prescriber can discuss continuing with monitoring or stopping. Stopping is always a valid choice; our guide to stopping dutasteride explains the timelines, including the long half-life.
Look at the whole picture. The NHS lists many causes of erection problems, including stress, tiredness, drinking too much alcohol, high blood pressure, high cholesterol, diabetes, depression or anxiety, hormone problems and other medicines. A GP can check for these, and a testosterone blood test or a look at erectile changes through our sister service can help separate a medicine effect from something else.
Report it. Use the MHRA Yellow Card scheme, whether or not you stop.
Mood matters too. The MHRA advises people taking dutasteride to consult a healthcare professional as soon as possible if they develop suicidal thoughts or depression, and to contact one if they experience sexual dysfunction. For finasteride, the May 2026 update also noted that sexual dysfunction may contribute to mood disorders, so mention both. For the wider evidence on persistence, see finasteride and persistent sexual dysfunction, and for the licensing position see is dutasteride licensed for hair loss?
When to seek urgent care
If you have thoughts of suicide or self-harm, or feel that life is not worth living, please get help now: - Call Samaritans on 116 123 (free, 24/7) - Text SHOUT to 85258 - Call NHS 111 and select the mental health option - Go to your nearest A&E, or call 999 if you are in immediate danger Then contact your prescriber or GP about stopping dutasteride.