Finasteride sexual side effects: how common are they?

Key facts

• UK SmPC, three 12-month trials (945 men on finasteride, 934 on placebo): decreased libido 1.8% vs 1.3%, erectile dysfunction 1.3% vs 0.7%, decreased ejaculate volume 0.8% vs 0.4%. Overall 3.8% vs 2.1%.
• The patient leaflet lists erection problems, less desire and ejaculation problems as uncommon (up to 1 in 100). The NHS lists them as common. The BAD gives about 2%. A 2026 systematic review gives 1.9% to 6.7% against 0.9% to 3.9% on placebo.
• The SmPC says these effects resolved in men who stopped and in many who continued. Persistent dysfunction after stopping is reported after marketing, with no rate.
• The MHRA (11 May 2026) says sexual dysfunction may contribute to mood disorders, and has also been reported without mood changes.
• Tell your prescriber early. Stopping is always a valid choice.

What counts as a sexual side effect

The Propecia (finasteride 1 mg) product information lists decreased libido, erectile dysfunction and ejaculation disorder (including decreased ejaculate volume) as uncommon effects. Testicular pain, blood in the semen and male infertility are listed with a frequency of "not known". After the tablet came on the market, persistent sexual dysfunction after stopping, covering decreased libido, erectile dysfunction and ejaculation disorder, was also reported, with no rate.

The MHRA's advice to patients is to contact your doctor about reduced sex drive, erection difficulties or ejaculation problems.

Do they go away?

The SmPC says: "Resolution of these side effects occurred in men who discontinued therapy with Propecia and in many who continued therapy". The NHS says the effects "usually improve after a while, but they can sometimes carry on even after you stop taking finasteride".

The MHRA is concerned about the group in whom they do not. In its 29 April 2024 Drug Safety Update it reported 426 Yellow Card reports of sexual dysfunction with finasteride (1 mg and 5 mg) between November 1992 and 5 April 2024, almost half recorded as "not recovered" or "not resolved". That is a count of reports, not a rate, and the MHRA says a reported reaction does not necessarily mean the medicine caused it. There is no test that predicts who will be affected. Our guide to persistent sexual side effects covers this in detail, and the post-finasteride syndrome entry explains the term.

What to do

Tell your prescriber early. You do not have to wait and see. Note what changed, when it started and how much it matters to you. They can talk through continuing with monitoring, or stopping.

Look at the whole picture. The NHS says occasional erection problems are usually caused by stress, tiredness or drinking too much alcohol, and your GP can check for other causes such as blood pressure, diabetes or hormone problems. See finasteride and alcohol.

Stopping is always valid. Our guide to stopping finasteride explains what happens to your hair and to side effects.

Report it. Report suspected side effects through the Yellow Card scheme.

Before starting finasteride, read the patient alert card, covered in what the finasteride patient alert card says, and tell the prescriber about any sexual or mood difficulties you already have.

Related questions