One of America’s top surgeons has warned men never to take a hair-loss drug that’s been found to cause permanent genital changes.
Called finasteride, the drug has been taken by the likes of President Donald Trump, Hollywood stars, as well as millions of other men.
However, Dr Edward Schaeffer, a consultant urologist who treated comic actor Ben Stiller for prostate cancer, warned men to steer clear of it due to common and potentially permanent side effects.
He said it is known to cause impotence and depression in one in ten men.
Finasteride recently sparked headlines over claims it can cause men’s genitals to shrink and permanently change shape.
At least 39 British men believe this has happened to them according to official data from the UK’s medicines watchdog.
Finasteride was originally developed for men with an enlarged prostate, but it has since become a popular hair loss treatment.
It works by blocking the male hormone testosterone’s conversion to dihydrotestosterone, or DHT.
Finasteride has been taken by the likes of President Donald Trump , Hollywood stars, as well as millions of other men
High levels of DHT are believed to lead to hair loss by shrinking follicles on the scalp.
But DHT is also crucial for sexual arousal, erectile function, and genital tissue health, and its reduction.
While the drug shows a remarkable ability to promote hair growth, some men have ending up paying a steep price.
UK data show there has been a three-fold rise in reports of finasteride causing depression, low libido and erectile dysfunction.
Data analysed by MailOnline also shows 39 men have reported to British drug safety regulators that their genitals shrank while taking the drug.
Another 16 reported they had developed Peyronie’s disease, when scar tissue forms in the penis causing it to bend or have curvature when erect.
The drug has also been reported as being involved in 87 cases of suicide, suicide attempts or self-harming behaviour, 12 of which were fatal.
These suspected side effects were logged under the Medicines and Healthcare products Regulatory Agency (MHRA) ‘Yellow Card’ scheme.
Mark Millich, 26, a former US Army sergeant, took finasteride pills to cure his baldness. Instead, his libido plunged as his genitals shrank and changed shape
Although impossible to prove, it allows doctors, pharmacists and patients to report adverse reactions they believe to be caused by drugs used in Britain.
Speaking on The Peter Attia Drive Podcast, Dr Schaeffer said he believed about one in 10 men who take the drug may suffer problems with intimacy and mental health.
‘The side effects from this post-finasteride syndrome are real,’ he said.
The duration can be highly variable. Some people will stop the medication, and they’ll have resolution within a couple weeks, once the drug washes out.
‘But there are people I know who have it permanently.’
Dr Schaeffer added that the problems seem to affect both young and older men, though the former are more likely to report issues with lower libido.
He also claimed the side-effects are likely linked to how the drug suppress DHT.
‘Having that hormone around is critical for just about everything,’ he said.
In the US, 32 complaints regarding finasteride products have been issued to the FDA between 2019 and 2024.
Customers have detailed incidents such as erectile dysfunction, anxiety, suicidal ideation, brain fog, depression, fatigue, insomnia, decreased libido and testicular pain after applying the hair-loss drug.
Most of the men and women who filed the complaints said these side effects continued to persist even when they stopped using the products.
Earlier this month, the US’s Food and Drug Administration issued a stark warning over the drug warning it may pose a ‘potentially serious risk’ to men’s genitals.
According to medics about 2 to 3 per cent of patients taking the drug experience sexual function problems, including erectile dysfunction, decreased libido and reduced ejaculate.
One man who detailed the shocking problems he experienced after taking finasteride is former US Army sergeant Mark Millich.
Earlier this year he said he took the drug in a bid to cure his baldness but instead found his libido plunged as his genitals shrank and changed shape.
‘I got Peyronie’s disease, that happened within a month or two after coming off finasteride,’ he told the YouTube channel Moral Medicine.
His doctors could not say whether the condition was caused by the medication, with Peyronie’s often linked to injuries sustained during sex that cause scar tissue to form in the penis.
A 2023 study showed that there have been more than 830 reports of ‘penile curvature’ or Peyronie’s disease to the US’s drug monitoring system among finasteride patients.
But scientists said the results were ‘highly speculative’ and ‘very questionable’, claiming more research was needed to determine whether the drug could cause the condition.
Other men have since come out with similar claims — alleging finasteride left them with shrunken or bent penises, burning testicles, and deep emotional scars.
UK’s health authorities urged men on finasteride to be ‘vigilant’ for possible psychiatric and sexual side effects in April last year.
Finasteride is not prescribed for hair loss on the NHS but is available privately in the UK for as little as £28 for a course.
