The dark side of hair loss drugs

For more than 20 years, regulators have sat on data that links a drug for male pattern baldness to depression and suicide. Bryan Hubbard reports

Second only to the family dog, finasteride has been touted as man’s best friend. The same drug combats two of men’s main worries: prostate problems, for which it’s marketed as Proscar, and hair loss, when it’s branded as Propecia.

But the drugs—and especially Propecia—have a dark side that has been hidden by the manufacturer and the US drug regulator, the Food and Drug Administration (FDA), for more than 20 years: They cause severe depression, and sufferers have committed suicide.

The actual numbers aren’t known because it’s impossible to track an adverse reaction if nobody is aware of the problem. But researchers reckon that several thousand men have taken their own lives, while hundreds of thousands have suffered from chronic depression.

Propecia has enjoyed light-touch regulation because it’s “just” a cosmetic treatment, but worries about its deadly side effects were being flagged back in 2002. Eight studies published between 2017 and 2023 established that it caused neurological problems, such as anxiety and depression, and raised the risk of chronic depression by 57 percent.¹

In 2011, the FDA finally accepted that Propecia could cause depression and added it to the list of potential adverse reactions. However, it took a petition generated by patients and their surviving families to finally compel the regulator to include a warning that it could lead to suicide.

The FDA added the warning to the medicine’s label as an informal notification in 2022 but never made it a “black box” warning—the most severe sanction before a drug is withdrawn, and which the petitioners had lobbied for. The European Medicines Agency followed suit only this year in recognizing the drug could lead to suicide.

Roots of the problem

The warnings were a long time coming: The FDA approved the drug as a treatment for male pattern baldness in 1997. It was the offshoot of Proscar, which had been approved in 1992 as a treatment for benign prostatic hypertrophy (BPH), but while it was shrinking the prostate gland, doctors were also noticing that their patients’ hair was growing back.

Five years later, Propecia was launched as a treatment for male pattern hair loss. It was still finasteride, but at a recommended lower dose of 1 g a day, while Proscar was being prescribed at 5 g.

Although the drug is treating two problems, it’s targeting the same biological processes. Finasteride is in a class of medications called 5-alpha-reductase inhibitors; it treats BPH by blocking the body’s production of testosterone and stops it converting to dihydrotestosterone (DHT), which is responsible for muscle mass and hair growth. DHT can also cause the prostate gland to enlarge.

Finasteride can be effective. Some studies have found it reduces DHT levels in the prostate gland by more than 90 percent and in the blood by 70 percent,² and others have found that up to 87 percent of men taking Propecia report their hair is growing back.³ But Propecia’s lower dose doesn’t lead to a complete elimination of DHT, and although hair loss slows, it still goes on. But it can stop if the drug is taken for a year.

In treating BHP, long-term use of finasteride reduces prostatic volume, relieving bothersome urinary symptoms attributed to an enlarged gland, such as the urge for a nocturnal visit to the toilet. Urinary retention is reduced, and the drug delays the need for surgical intervention.

But it’s all short-term; within 14 days after stopping the drug, the DHT level returns to normal, and with it all the usual prostate problems. Similarly, hair loss comes back when men stop taking Propecia.

Essentially, by making men less masculine, the drug revives hair growth and reduces prostate swelling—but that’s a double-edged sword. Men on either drug also report erectile dysfunction and a loss of libido.

Less of a man

Because it emasculates men, Proscar is often the first drug of choice for transgender women (men who identify as women). The drug is routinely used in combination with estrogen for its anti-androgen properties, which suppress male hormones like testosterone.

Some researchers have suggested a loss of masculinity—and specifically male sexual function—is the reason men on the drug are committing suicide, and suicidal thoughts can continue long after stopping treatment.⁴

Finasteride could also lead to a deadly type of prostate cancer. The Prostate Cancer Prevention Trial (PCPT) compared daily finasteride to placebo therapy in over 18,000 men aged 55 and older and tracked them for seven years. The good news was that the drug reduced the prevalence of prostate cancer by 25 percent—but it also increased the rate of high-grade deadly cancer. Unlike with depression and suicide, the FDA responded quickly and issued a black box warning.⁵

A side effect nobody anticipated was orthostatic hypotension, or postural hypotension—dizziness when standing up quickly due to a drop in blood pressure to the brain. The problem affects around 9 percent of men on the drug, and that number doubles when finasteride is taken with another drug.

But it’s the foot-dragging over depression and suicide that has bugged Prof. Mayer Brezis, a public health expert at the Hebrew University of Jerusalem. For years, the manufacturer Merck and the FDA sat on their hands despite the growing evidence that was suggesting a link to depression, anxiety and suicidal thoughts.¹

He points to eight large studies published between 2017 and 2023 that show a clear trend: People who used finasteride were far more likely to experience mood disorders and suicidal thoughts than people given a placebo. 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. We now see consistent patterns across diverse populations. And the consequences may have been tragic,” said Brezis.

Not many dead

But just how many victims there have been, we just can’t say. More than 8 million people around the world are using Propecia, and yet public records have been recording just a few cases of suicide among people taking it.

The FDA may well have known the problem went far deeper. Internal FDA files from 2010, cited in Brezis’s review, contained entire sections redacted as “confidential,” including estimates of how many people were affected.

By 2011, only 18 suicides linked to finasteride had been reported to the FDA. Based on worldwide usage, Brezis concluded the actual, but still underreported, number should have been in the thousands. “It wasn’t just underreporting,” he said. “It was a systemic failure of pharmacovigilance.”

With so many drugs that treated life-threatening health problems to regulate, perhaps the FDA took a more relaxed approach to a cosmetic treatment. Merck certainly seemed to adopt that view; it didn’t initiate a single study into the drug’s effectiveness or dangers, and all the red-flag warnings came from trials from independent researchers.

“This wasn’t about life-or-death medical necessity—this was about hair,” said Brezis.

Finasteride tackles some of men’s problems by blocking DHT production, but this comes with another reaction that nobody foresaw: It may also disrupt neurosteroids like allopregnanolone, which is linked to mood regulation in the brain. Animal studies have shown long-term effects on neuroinflammation and even changes in the brain’s hippocampus, which regulates emotions and memory.

But stopping treatment doesn’t stop the problems. Lingering symptoms, known as “post-finasteride syndrome,” include insomnia, panic attacks, cognitive dysfunction and suicidal thoughts that persist months or even years after treatment ends.

All change

Brezis is calling for immediate changes in how cosmetic drugs like finasteride are approved, monitored and prescribed. His recommendations include suspending marketing of the drug for hair loss until safety is reestablished, mandating post-approval studies with strict enforcement and systematically recording drug histories in suicide investigations.

He shouldn’t hold his breath. Finasteride’s advocates—often cosmetic clinics—still push it as if it’s a harmless remedy.

“Think of finasteride as your hair’s personal bodyguard,” says one, then continues breathlessly, “Here’s what I love telling my patients about hair thickening with finasteride—it’s like giving your hair follicles a fresh start.

“By reducing dihydrotestosterone levels, the medication allows your follicles to produce thicker, stronger hair strands. Think of it like this: Your hair follicles are like tiny gardens. Remove the weeds (DHT), provide good soil (proper blood flow) and suddenly your plants (hair) can grow much better!”

These claims are helping to drive a multibillion-dollar industry. The demand for finasteride is growing, market commentators say. They’re predicting a steady increase in sales as populations age, and the focus on youthfulness—or at least looking young—is amplified. Annual sales of finasteride reached $362.1 million in 2021 and are projected to reach $546.7 million by 2031, although it still lags behind Rogaine (minoxidil), the market leader for hair loss treatment.

Talk of depression and suicide spoils the party, and any changes to regulation and safety reporting that Brezis is advocating will have come too late for the many thousands who have already taken their own lives, he says.

Tellingly, his paper was dedicated to one man—a previously healthy man who took finasteride “just” to improve his hair. Within days, he spiraled into severe psychiatric distress. He never recovered. Months later, he took his own life.

What do you think? Start a conversation over on the... WDDTY Community