Hair-loss drug Finasteride has long been tied to depression and suicide, but researchers say regulators have ignored the warnings, with a recent analysis by a public health expert slamming authorities and the manufacturer after global data showed psychiatric harm and a pattern of inaction by Merck and the FDA.
Professor Mayer Brezis from the Hebrew University of Jerusalem said that despite its cosmetic use, the drug’s effects on brain chemistry can be devastating, and has called for urgent regulatory reforms and post-marketing studies to protect public health.
Brezis said Finasteride has been associated with depression and suicide for more than 20 years, but despite these long-standing concerns, neither regulators nor the drug’s manufacturer took meaningful action or launched the necessary safety investigations.
Drawing on adverse event reports and health records from several countries, his review, published in The Journal of Clinical Psychiatry, identifies a consistent pattern of psychiatric side effects linked to the drug, and he has appealed for major reforms on how medications are approved and monitored for long-term risks.
Cosmetic appeal
For more than two decades, finasteride has been prescribed to millions of men seeking to slow or reverse hair loss. Behind its cosmetic appeal, however, evidence has continued to emerge suggesting serious mental health consequences, including depression, anxiety, and in some cases, suicide.
Brezis, whose review analysed data from eight large studies published between 2017 and 2023, said signs of psychiatric harm associated with the drug have consistently been ignored.
The findings show a clear trend: people who used finasteride were far more likely to experience mood disorders and suicidal thoughts than those who did not. This pattern appeared consistently across various national databases, including the FDA's adverse event system and healthcare records from Sweden, Canada, and Israel.
“The evidence is no longer anecdotal,” said Brezis, a Professor Emeritus of Medicine and Public Health. “We now see consistent patterns across diverse populations. And the consequences may have been tragic.”
The report estimates that hundreds of thousands of users may have suffered from finasteride-related depression, and that hundreds – possibly more – may have committed suicide.
Originally approved by the FDA in 1997 for male pattern baldness, the drug has remained popular for its perceived safety and effectiveness, particularly among younger men.
Delayed response, high cost
Although the FDA recognised depression as a possible side effect in 2011 and added “suicidal thoughts” to the label in 2022, researchers had been warning of potential dangers from as early as 2002.
Internal FDA files from 2010, cited in Brezis’ review, contained entire sections redacted as “confidential”, including estimates of how many people might have been affected.
By 2011, only 18 suicides linked to finasteride had been reported to the FDA. Based on worldwide usage, Brezis concluded the actual number should have been in the thousands.
“It wasn’t just under-reporting,” he wrote. “It was a systemic failure of pharmacovigilance.”
Unlike drugs used to treat obesity or psychiatric disorders, which are often closely monitored after approval, finasteride’s classification as a cosmetic treatment may have shielded it from deeper scrutiny. None of the data-mining studies referenced in the review was initiated by Merck, which developed the drug, nor were they commissioned by regulatory authorities.
Cosmetic drug with life-altering risks
Brezis argues that the drug’s classification as a non-essential, appearance-enhancing medication changes the risk calculus. “This wasn’t about life or death medical necessity,” he said. “This was about hair.”
The biological rationale is clear. Finasteride works by blocking the conversion of testosterone into dihydrotestosterone (DHT), but in doing so, it may also disrupt neurosteroids like allopregnanolone – linked to mood regulation in the brain.
Animal studies have shown long-term effects on neuroinflammation and even changes in hippocampal structure.
For some patients, the consequences don’t end when the pills do. Reports of lingering symptoms, dubbed “post-finasteride syndrome”, include insomnia, panic attacks, cognitive dysfunction, and suicidal thoughts that persist months or even years after stopping treatment.
Regulatory gaps, corporate silence
The report is especially scathing toward the FDA and Merck. Despite having access to millions of patient records and robust pharmacovigilance tools, neither party acted in time, Brezis argues.
The industry’s silence was strategic, he suggests, driven by market pressures and legal liability – echoing past controversies like Merck’s handling of Vioxx.
The FDA, meanwhile, took five years to respond to a citizen petition calling for a black-box warning. Its final decision? To add suicidal ideation to the label – but not as a formal warning.
What now?
Brezis is calling for immediate changes in how drugs like finasteride are approved, monitored, and prescribed. His recommendations include suspending marketing of the drug for cosmetic purposes until safety is re-established, mandatory post-approval studies with strict enforcement, and systematic recording of drug histories in suicide investigations.
“For many, those changes come too late. The paper is dedicated to one such individual – a previously healthy man who took finasteride ‘just’ to improve his hair. Within days, he spiralled into severe psychiatric distress. He never recovered. Months later, he took his own life.”
Study details
Failing Public Health Again? Analytical Review of Depression and Suicidality From Finasteride
Mayer Brezis
Published in The Journal of Clinical Psychiatry on 22 September 2025
Abstract
Background
Finasteride, widely prescribed for androgenetic alopecia, has long been suspected of causing severe neuropsychiatric reactions, including depression, anxiety, and suicidality, even after the drug is discontinued. This study systematically reviews evidence that supports this suspicion and analyses the reasons for this delayed recognition.
Observations
Concerns about depression from finasteride were raised in several studies as early as 2002. Between the years 2017 and 2023, 4 independent analyses of adverse event reporting systems and four studies using data mining of healthcare records indicated a significant increase in the risk for depression, anxiety, and/or suicidal behaviour with the use of finasteride. There has been, therefore, a two-decade delay in the realisation of the incidences and the gravity of neuropsychiatric effects, allowing harm from a medicine prescribed for a cosmetic indication of hair loss.
Potential Harms and Implications
Over 20 years worldwide, hundreds of thousands may have endured depression, and hundreds may have died by suicide. According to the precautionary principle, such a risk from a cosmetic medication suggests a benefit-to-harm balance that justifies action to protect the public, and the burden of proving that the intervention is not harmful falls on manufacturers.
Causes for Delayed Risk Recognition
The long delay in recognising the risks associated with finasteride exposure includes the manufacturer’s failure to perform and publish simple pharmacovigilance studies using database analyses and regulators’ failure to request such studies from the manufacturer or to perform them.
Conclusions and Relevance
Current evidence shows that finasteride use can cause depression and suicidality. A historical literature review discloses gaps between research evidence and regulatory steps. The lesson is that before approving a medication for the market, regulators should require manufacturers to commit to performing and disclosing ongoing postapproval analytical studies, and this requirement needs to be enforced.
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