Finasteride and Dutasteride: What Patients Should Know About New MHRA Warnings

The UK medicines regulator has strengthened safety warnings for finasteride and dutasteride after reviewing evidence around possible psychiatric side effects and sexual dysfunction.

The Medicines and Healthcare products Regulatory Agency (MHRA) published an updated Drug Safety Update on 11 May 2026, advising healthcare professionals and patients to be more aware of risks including low mood, depression, suicidal thoughts and sexual side effects linked to finasteride. Dutasteride product information is also being updated as a precaution because it belongs to the same medicine class.

What Are Finasteride and Dutasteride Used For?

Finasteride and dutasteride are medicines known as 5-alpha-reductase inhibitors.

Finasteride 1mg is commonly used for male pattern hair loss, while finasteride 5mg is used for benign prostatic hyperplasia, also known as an enlarged prostate. Dutasteride 0.5mg is also used to treat benign prostatic hyperplasia and may be prescribed to reduce the risk of acute urinary retention.

Because these medicines are used by many men, the updated safety advice is important for both patients and prescribers. The MHRA said prescribing data suggests more than 400,000 prescriptions per month are issued for finasteride 5mg and dutasteride-containing medicines.

What Has the MHRA Warned About?

The MHRA has confirmed that finasteride is associated with depression, suicidal ideation and sexual dysfunction, and in some cases, sexual side effects may persist after treatment is stopped. Reported sexual side effects include reduced sex drive, erectile dysfunction and ejaculation disorders.

The updated product information for finasteride 1mg will now include clearer warnings that sexual dysfunction may contribute to mood disorders, and that sexual dysfunction has also been reported without mood changes.

For dutasteride, the MHRA said available data is limited. However, because dutasteride works in a similar way to finasteride, a precautionary warning is being added to its product information about mood changes reported with finasteride.

What Should Patients Do?

Patients taking finasteride or dutasteride should not ignore changes in mood, mental health, or sexual function.

The MHRA advises that patients taking finasteride 1mg should stop the medicine immediately and contact their doctor as soon as possible if they develop depression or suicidal thoughts. Patients taking finasteride 5mg or dutasteride should contact their healthcare professional as soon as possible if they experience depression or suicidal thoughts.

Patients should also speak to a doctor or pharmacist if they notice sexual side effects such as reduced libido, difficulty getting or maintaining an erection, or ejaculation problems while taking finasteride or dutasteride.

Anyone who feels at risk of serious harm or has seriously harmed themselves should call 999 immediately.

Why Patient Alert Cards Matter

Finasteride patient alert cards were introduced in the UK in 2024 and remain in place. These cards highlight the risks of psychiatric and sexual side effects and explain what action patients should take if symptoms occur.

The MHRA is advising healthcare professionals to discuss these risks at the point of prescribing and to remind patients to read both the patient alert card and the patient information leaflet supplied with finasteride packs.

This is especially important for patients using finasteride privately for hair loss, as they may not always have the same level of ongoing review as patients receiving long-term treatment for prostate symptoms.

What Should Healthcare Professionals Consider?

The MHRA has advised prescribers to check a patient’s medical record and ask about any personal history of depression or suicidal thoughts before prescribing finasteride. Patients should also be reviewed regularly for psychiatric or sexual side effects during treatment.

This updated guidance supports better conversations between patients and healthcare professionals, helping patients understand both the benefits and possible risks before starting treatment.

Reporting Side Effects

Patients, carers and healthcare professionals are encouraged to report suspected side effects linked to finasteride or dutasteride through the Yellow Card scheme. The MHRA uses these reports to monitor medicine safety and identify potential risks.

The MHRA said Yellow Card data from 1994 to 31 May 2025 included 170 reports of suicidal ideation and related terms for finasteride and 5 reports for dutasteride. The regulator also noted that Yellow Card reports are suspected reactions and do not automatically prove that a medicine caused the event.

Final Thoughts

The updated MHRA warnings do not mean every patient will experience these side effects, but they do highlight the importance of being informed before and during treatment.

For anyone taking finasteride or dutasteride, the key message is simple: pay attention to changes in mood, mental health and sexual function, and speak to a healthcare professional if symptoms occur.

Patients should never feel embarrassed about discussing these side effects. Early advice can help ensure treatment remains safe, suitable and properly monitored.