MHRA tightens the warnings on 5-ARIs / DHT blockers

Safety warnings from from MHRA on the use of 5-alpha reductase inhibitors, sometimes referred to as DHT blockers.

On 11 May, the MHRA released a new Drug Safety Update on finasteride and dutasteride. This update strengthens warnings about suicidal thoughts and behaviours, depression and sexual dysfunction. It also revises the product information for both drugs.¹ This comes after the 2025 EU Article 31 referral, the introduction of UK finasteride patient cards in 2024, and a further review by the Commission on Human Medicines.¹

Reminder of indications: finasteride is used to treat male pattern hair loss (androgenetic alopecia) at a dose of 1mg, and benign prostatic hyperplasia at a dose of 5mg. Dutasteride 0.5mg is used to treat benign prostatic hyperplasia and to reduce the risk of acute urinary retention.¹

Over 400,000 NHS prescriptions are issued monthly for finasteride 5mg and dutasteride. This figure excludes the larger private market for finasteride 1mg, which is not available on the NHS and where most of the Yellow Card signal sits.¹

The headline change concerns finasteride 1mg, used in androgenetic alopecia. The MHRA advice to patients is now to stop finasteride 1mg immediately if they develop depression or suicidal thoughts, and to contact their doctor as soon as possible.¹ The SmPC and PIL for finasteride 1mg are being updated with a warning that sexual dysfunction may contribute to mood disorders, and that sexual dysfunction has also been reported without mood alterations.¹

For finasteride 5mg and dutasteride, the advice differs. Patients are not advised to stop the medicine, but to consult their healthcare professional as soon as possible if they develop depression or suicidal thoughts, or if they experience sexual dysfunction.¹ Dutasteride data are limited, but as a precaution the dutasteride SmPC and PIL are being updated to note that mood alterations have been reported with another medicine in the same class (finasteride).¹

The Yellow Card picture is worth understanding.

Between 1994 and 31 May 2025, the MHRA received 170 reports of suicidal ideation and related terms for finasteride (1mg and 5mg combined), including 19 fatal reports of suicide. For dutasteride 0.5mg, there were 5 reports of suicidal ideation and no fatal reports.¹ The majority of reports were from men on the 1mg dose for hair loss, which is the population most affected by these new warnings.¹ Yellow Card data are signal-generating rather than causal, and the literature reviewed during the European referral was mixed. The regulatory action is precautionary, but the addition of the sexual-dysfunction-and-mood pathway warning is a meaningful clinical shift.

For patients on finasteride 1mg, point them to the UK Finasteride patient cards and the patient information leaflet, both of which are supplied in 1mg and 5mg packs. The product information is being updated by manufacturers, so older packs may still carry the previous leaflet wording.¹

Expect more men to bring this up in NHS appointments now that press coverage is widening, and have the patient cards conversation ready.²

A note for Medicine Central readers in private practice: finasteride 1mg is not available on NHS prescription. A significant share of the men affected by these warnings are obtaining it via online private clinics and pharmacy services, where pre-prescription mental health screening varies considerably.¹

Suspected adverse drug reactions associated with finasteride or dutasteride should be reported via the Yellow Card scheme.¹

References

1. Medicines and Healthcare products Regulatory Agency. Finasteride and Dutasteride – updated safety warnings for psychiatric side effects and sexual dysfunction. Drug Safety Update vol 19, issue 10, May 2026: 1. Published 11 May 2026. https://www.gov.uk/drug-safety-update/finasteride-and-dutasteride-updated-safety-warnings-for-psychiatric-side-effects-and-sexual-dysfunction

2. Medicines and Healthcare products Regulatory Agency. MHRA strengthens safety warnings for finasteride and dutasteride. Press release, 11 May 2026. https://www.gov.uk/government/news/mhra-strengthens-safety-warnings-for-finasteride-and-dutasteride

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