Decades of Studies Link Suicide Risk With Common Hair Loss Treatment

Many prescription medicines arrive with a daunting catalogue of possible harms, yet the real issue is rarely the length of the list. What matters is the probability and severity of those adverse effects - and whether the risks are proportionate to the benefit the treatment is meant to deliver.

A recent study argues that, for at least one widely used medicine, those risk–benefit questions have not been examined with sufficient rigour for years. The author also suggests that the same gaps in oversight may still be leaving patients unnecessarily exposed to dangers from other pharmaceuticals.

Finasteride: safety signals behind a common treatment for male pattern hair loss and benign prostatic hyperplasia

The analysis centres on finasteride, a prescription medicine taken by millions of men since the 1990s. It is routinely prescribed for male pattern hair loss and for benign prostatic hyperplasia (a non-cancerous enlargement of the prostate).

Mayer Brezis - a retired nephrologist and former medical professor at the Hadassah–Hebrew University Medical Centre in Israel - writes that concerns about finasteride’s impact on mood have been circulating for a long time. In his view, growing evidence associating the drug with serious psychiatric outcomes - including anxiety, depression, and suicidality - has not been acted upon adequately by manufacturers, clinicians, or regulators, to the detriment of public health.

What the review found: consistent links with mood disorders and suicidal thoughts

Brezis’s literature review draws on eight studies published from 2017 to 2023, combining evidence from multiple countries and different health data systems.

Taken together, the results indicate that people using finasteride have a markedly higher likelihood of developing mood disorders and experiencing suicidal thoughts compared with people who do not take the drug.

“The evidence is no longer anecdotal,” Brezis says. “We now see consistent patterns across diverse populations. And the consequences may have been tragic.”

Regulatory timeline: FDA warnings, internal deliberations, and transparency

In the United States, the Food and Drug Administration (FDA) added depression as a possible adverse effect of finasteride in 2011, and later included suicidality in 2022 - even though researchers had been flagging concerns as far back as 2002.

Brezis reports that, in litigation connected to the suicide of a finasteride user, internal FDA documents suggested the agency’s specialists had recommended adding “suicidal thoughts and behaviour” to the warning label in 2010.

According to Brezis, that recommendation was not accepted, and the agency did not publish the internal discussion or explain the reasoning behind its final position. He also points to sections of FDA documents that were withheld as confidential, including estimates of how many people might be affected.

“Transparency is crucial when facing inherent conflicts between innovation and safety, progress and public health,” Brezis writes.

Pharmacovigilance and undercounting: why recorded cases may be the tip of the iceberg

By 2011, the FDA had logged 18 suicides linked to finasteride. Brezis argues that, given worldwide use of the drug, the true number could plausibly run into the thousands. He attributes this not simply to underreporting, but to what he calls “a systemic failure of pharmacovigilance”.

In his assessment, the shortcomings include the original manufacturer, Merck, failing to carry out straightforward safety work using large database analyses. He also criticises regulators for not requesting that the manufacturer undertake such studies - or performing the analyses themselves.

In 2021, Merck told Reuters: “The scientific evidence does not support a causal link between Propecia [a brand name for finasteride] and suicide or suicidal ideation and these terms should not be included in the labelling.”

The company added: “Merck works continuously with regulators to ensure that potential safety signals are carefully analysed and, if appropriate, included in the label for Propecia.”

Brezis notes that none of the studies included in the latest review were initiated by Merck or by regulators. He suggests that limited regulatory attention may, in part, reflect finasteride’s categorisation as a cosmetic treatment when used for hair loss.

Possible biological pathways: DHT, neurosteroids, and the hippocampus

Finasteride reduces hair loss by interfering with the conversion of testosterone into dihydrotestosterone (DHT). However, the drug also suppresses the production of certain neurosteroids, including allopregnanolone, which has been associated with mood regulation.

Animal studies have linked finasteride exposure to prolonged effects on brain inflammation and to structural changes in the hippocampus - a region involved in learning, memory, and emotional processing.

Post-finasteride syndrome: symptoms that may persist after stopping

A further concern raised in the paper is that psychiatric adverse effects may not always resolve once the medicine is discontinued. Brezis points to the possibility that symptoms can continue for months or years, a pattern often described as post-finasteride syndrome.

Conflicts of interest, decision-making, and what “safety” should mean

Brezis argues that financial incentives can, in practice, take precedence over patient safety - and he believes finasteride may be an example of that dynamic. In his view, responsibility does not sit solely with manufacturers: regulators also have a duty to ensure safety questions are actively investigated rather than passively awaited.

This matters because finasteride is often taken for long periods, particularly for hair loss, where the benefit is typically quality-of-life or cosmetic rather than life-saving. In such circumstances, the threshold for acceptable risk may be different - and clear, up-to-date information is essential for meaningful informed consent between clinician and patient.

For readers in the United Kingdom, the broader message is also about systems: robust post-marketing monitoring and timely label updates rely on regulators and healthcare systems acting on emerging signals. Whether oversight sits with the FDA in the US or the MHRA in the UK, Brezis’s central claim is that safety surveillance must be treated as an ongoing obligation, not a one-off hurdle cleared at approval.

The author’s recommendations: approval standards and mandatory ongoing studies

Brezis concludes that medicines such as finasteride should not be authorised unless safety can be established convincingly. He further argues that, once a drug is on the market, continuing safety research should be legally required so that approval remains justified as evidence accumulates.

“The lesson is that before approving a medication for the market, regulators should require manufacturers to commit to performing and disclosing ongoing post-approval analytical studies, and this requirement needs to be enforced,” Brezis writes.

Publication

The study was published in the Journal of Clinical Psychiatry.

If this has raised worries for you, or you feel you need support, please seek help immediately. In the UK and Republic of Ireland, you can contact Samaritans free on 116 123 (24/7) or visit samaritans.org. If you are elsewhere, look up a 24-hour crisis hotline in your country and reach out for assistance.