A common hair loss drug that promises to halt a receding hairline has been linked to suicide, a new study suggests.

Finasteride, sold under the brand name Propecia and available by prescription, has surged in popularity in recent years after doctors said it could slow male hair loss with little more than a pill a day.

But as more men turn to the drug, reports of troubling side effects have mounted, with some claiming it left them battling mood swings, loss of libido and even genital shrinkage.

Now, a review of existing literature has concluded that those taking the medication may be at higher risk of suicidal thoughts or behaviors.

Israeli researchers analyzed eight studies, published between 2017 and 2023, and found a significantly higher risk of suicidal behavior among those taking the drug compared to those who were not taking the medication.

It’s unclear why finasteride may raise suicide risk, but researchers say it may lower levels of brain chemicals that calm the nervous system and ease stress. 

Dr Mayer Brezis, an internist at the Hadassah-Hebrew University Medical Center who led the study, said: ‘The evidence is no longer anecdotal.

‘We now see consistent patterns across diverse populations. and the consequences may have been tragic.’

Finasteride was approved to treat male hair loss in 1997 and is now prescribed to an estimated 7.5million people every year, almost all men. (The drug is not approved for women, but may be prescribed off-label for female hair loss).

It has been taken by celebrities including Elon Musk, and is even rumored to have been used by President Donald Trump to combat his hair loss, though this has never been confirmed.

The FDA first added depression as a possible side effect of taking finasteride in 2011, and updated the label in 2022 to add suicidal behaviors, though researchers had raised concerns over a potential link as early as 2002.

Data from the monitoring system FDA Adverse Event Reporting System (FAERS), shows nearly 300 suicides among people who took the drug between 1993 and 2025, along with 111 suicide attempts and six suspected suicides.

The FAERS system is not verified, and claims can be submitted by anyone. It also only highlights correlations, which do not necessarily prove that any drug directly caused a side effect. 

In the latest scientific review, published in the Journal of Clinical Psychiatry last month, the researchers warned the drug may have caused ‘hundreds of thousands’ of cases of depression and hundreds of suicides since it was approved. 

The paper reviewed four studies that analyzed suicide reports among finasteride users from multiple adverse events reporting systems, such as the FDA’s FAERS, and four studies that analyzed healthcare records to determine whether finasteride raised the risk of suffering from depression or other mental problems.

It included a 2017 study by Canadian researchers that analyzed data on 93,000 men who started taking finasteride between 2003 to 2013. 

That research warned those on the drug had an 88 percent higher risk of being diagnosed with depression within the first 18 months of starting on the drug. It did not find a higher risk of suicide.

The review also analyzed a 2024 study involving more than 50,000 men with hair loss, including 23,300 who were prescribed finasteride. Results showed patients who took the drug were 40 percent more likely to be diagnosed with anxiety or depression than those who did not use the drug.

The paper concludes: ‘Current evidence shows that finasteride use can cause depression and suicidality.

‘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.’ 

The review, however, disclosed that it had significant limitations, including the chance the large databases researchers used could potentially contain errors and poor data.

A poor dataset contains errors, gaps or inconsistencies, for example, incorrect birth dates or missing fields. It may also be one where users changed how they recorded information over time.

The researchers also noted that the suggestion in their paper that finasteride could have caused hundreds of suicides was ‘highly speculative’ and said that more research was needed.

Finasteride works by blocking an enzyme that converts testosterone into another hormone called dihydrotestosterone (DHT), which is linked to hair loss.

Medical information from the FDA estimates that more than one in 100 people who take the drug experience problems getting an erection, a lower libido and problems with ejaculation.

In one in 1,000 people, the drug has been linked to swelling and tenderness in the chest and low mood, or depression.

In an update in 2022, the FDA added a warning to the drug’s label over a potential link to suicides, with the label now including under the section side effects: ‘Nervous system/Psychiatric: Depression, suicidal ideation and behavior’.

Its manufacturer, Merck, told Reuters in 2021 that the scientific evidence ‘does not support’ a ‘causal link’ between finasteride and suicides or suicidal thoughts, adding that these terms ‘should not be included in the labeling’.

It continued: ‘Merck works continuously with regulators to ensure that potential safety signals are carefully analyzed and, if appropriate, included in the label for Propecia [finasteride].’

Daily Mail contacted Merck ahead of the publication of this article for comment.

About 49,000 Americans die by suicide every year, which is the second leading cause of death among adults aged 10 to 34 years old. About 80 percent of suicides recorded every year are in men, according to the CDC.