Israeli study warns of popular hair-loss drug's links to increased suicides

A widely used hair-loss drug, finasteride, may pose serious mental health risks that have been overlooked for decades, according to a new review by Prof. Mayer Brezis of the Hebrew University of Jerusalem. His research exposes long-ignored evidence linking the drug to depression, anxiety, and suicide, and accuses both regulators and manufacturers of failing to act despite years of warning signs.

Approved by the US Food and Drug Administration (FDA) in 1997, finasteride—sold under brand names such as Propecia—was hailed as a breakthrough treatment for male pattern baldness. It works by blocking the conversion of testosterone into dihydrotestosterone (DHT), a hormone responsible for hair loss.

However, as reported in an article by SciTechDaily, this same mechanism also interferes with the brain’s production of neurosteroids, including allopregnanolone, a key regulator of mood and stress response. Animal studies have shown that disrupting these neurosteroids can cause neuroinflammation and structural brain changes, particularly in the hippocampus, an area linked to depression.

Brezis argues that because finasteride is a non-essential cosmetic drug, the acceptable risk threshold should be far lower than for life-saving medications. “This wasn’t about life or death medical necessity,” he said. “This was about hair.” Yet, despite its elective use, regulators and physicians continued to prescribe the drug widely, even as mounting evidence suggested potentially severe psychiatric side effects.

The review draws on global data from adverse event reports, clinical studies, and national health registries. Across eight major studies conducted between 2017 and 2023, researchers consistently found that users of finasteride were significantly more likely to develop mood disorders or suicidal thoughts compared to non-users. This pattern appeared in multiple countries, including the US, Sweden, Canada, and Israel, and across different populations. “The evidence is no longer anecdotal,” Brezis said. “We now see consistent patterns across diverse populations. And the consequences may have been tragic.”

Reports also highlight what has been termed post-finasteride syndrome (PFS)—a condition where symptoms such as insomnia, panic attacks, cognitive impairment, and suicidal ideation persist long after discontinuing the medication. For some patients, the effects have lasted months or even years, suggesting potentially irreversible neurological changes.

Despite early warnings—some dating back to 2002—both Merck, the drug’s manufacturer, and the FDA have been criticized for their inaction. The FDA first acknowledged depression as a side effect only in 2011, nearly fifteen years after finasteride’s approval, and added suicidality to the drug’s label in 2022. Internal FDA documents from 2010, cited in Brezis’s paper, contained entire sections redacted as “confidential,” including estimates of how many patients may have been affected.

According to Brezis, this long-term neglect represents a systemic failure of pharmaceutical oversight. He estimates that hundreds of thousands of men worldwide may have suffered from depression due to finasteride use, and that hundreds—if not more—may have died by suicide.

What needs to happen next

The review’s findings have renewed calls for urgent regulatory reform. Brezis proposes several measures to prevent similar lapses in the future. These include:

Suspending marketing of finasteride for cosmetic use until its psychiatric safety is fully re-evaluated.

Mandatory post-approval studies and stricter enforcement of safety monitoring.

Systematic recording of medication histories in suicide investigations to identify potential drug-related links.

He also urges public health authorities to reexamine how risk-benefit assessments are made for drugs that serve aesthetic rather than medical purposes. The case of finasteride, he warns, illustrates how the pursuit of cosmetic enhancement can come at a devastating psychological cost when pharmaceutical vigilance fails.

By Nazrin Sadigova