Regulatory tracker

MHRA safety updates on hair loss medicines

Every Drug Safety Update from the UK regulator that affects a medicine we prescribe, in date order, with a link to the original. What the MHRA said is kept separate from what we think it means, so you can tell the two apart.

Last update tracked: 11 May 2026

Most hair loss services do not publish this. It is not an oversight on their part: writing down what the regulator has said about the medicine you are selling is uncomfortable. We publish it because you cannot give informed consent to a treatment whose known risks you were never shown, and because a prescriber who will not tell you the bad news is not a prescriber worth having.

Finasteride · Dutasteride

Finasteride and dutasteride: updated safety warnings for psychiatric side effects and sexual dysfunction

What the MHRA said

The MHRA strengthened the finasteride warnings covering psychiatric reactions and sexual dysfunction, including effects reported to persist after treatment is stopped, and added a precautionary warning for dutasteride: mood changes have been reported with finasteride, and the data for dutasteride are very limited.

What it means if you are taking this

Dutasteride is used off-label for hair loss in the UK, so it is easy to assume the finasteride safety position does not apply to it. As of this update it carries its own precautionary warning, even though the evidence for dutasteride is very limited. If you are on dutasteride rather than finasteride, treat mood or sexual changes seriously and tell your prescriber, and dutasteride has a terminal half-life of roughly five weeks against finasteride's six hours, so anything you do notice takes considerably longer to clear.

Affects what we range as Finasteride 1 mg tablets, Dutasteride 0.5 mg capsules, Finasteride and minoxidil topical combination.

Finasteride

Finasteride: reminder of the risk of psychiatric and sexual side effects

What the MHRA said

The MHRA reminded prescribers and patients of the risk of psychiatric side effects, naming depression and suicidal ideation, and of sexual side effects including reduced libido, erectile dysfunction and ejaculation disorders. Patient alert cards were introduced into finasteride packs.

What it means if you are taking this

This is the update that changed what a responsible prescriber has to tell you before you start. The patient alert card in the box is not packaging filler: it exists because the regulator concluded people were starting finasteride without being told what to watch for. If a service prescribed you finasteride without raising any of this, that is a reasonable thing to be unimpressed by.

Affects what we range as Finasteride 1 mg tablets, Finasteride and minoxidil topical combination.

Biotin (vitamin B7)

Biotin can interfere with blood test results

What the MHRA said

The MHRA warned that high-dose biotin, widely sold in hair, skin and nail supplements, can interfere with immunoassay-based laboratory tests and produce falsely high or falsely low results, depending on the platform and the analyte.

What it means if you are taking this

This is the least known item on this page and the one most likely to affect someone reading it. Many hair supplements contain 5 to 10 mg of biotin, hundreds of times the dietary requirement. Take one before a thyroid, hormone or troponin test and the number that comes back may be wrong in either direction. Hold high-dose biotin for at least 48 to 72 hours before any blood draw, and tell the lab if you cannot.

This page tracks updates affecting medicines we prescribe. It is not a complete record of MHRA activity: the regulator publishes a Drug Safety Update most months covering the whole formulary, and the full archive is on gov.uk. If you think we have missed one that belongs here, tell us and we will add it.

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