To many men, it’s a wonder drug that has helped halt their baldness.

Others, however, say it has had a devastating effect on their lives, causing a range of crippling side-effects including impotence, infertility, insomnia, anxiety, depression and, in some cases, suicidal thoughts — even years after they stopped taking it.

The drug is finasteride, sold under the brand name Propecia, which is used to treat male pattern baldness. Donald Trump and Wayne Rooney are reportedly two of the millions who have used it in the hope of reversing a receding hair line or bald spot.

Globally, the market for hair loss treatments is valued at an extraordinary £5.6 billion, with male pattern baldness accounting for 90 per cent of that, and finasteride the most commonly used treatment.

And finasteride does work for male pattern baldness, improving hair growth within months, according to multiple studies. The effects last as long as the man continues to take the drug.

Worth it? Although finasteride is successful at stopping hair loss, some men say it has had a devastating effect on their lives, causing a range of crippling side-effects including impotence, infertility, insomnia, anxiety, depression and, in some cases, suicidal thoughts

In simple terms, it stops hair loss by reducing the conversion of the male hormone testosterone into dihydrotestosterone (DHT). High levels of DHT cause hair follicles on the scalp to shrink, leading to hair loss. Finasteride not only prevents this, it has also been shown to encourage regrowth.

In the UK, when it comes to treating hair loss, the drug is available on private prescription only — from doctors since 1999 and, since 2014 and with a prescription, from a pharmacist.

It is, however, available on NHSprescription under the brand name Proscar — and at a higher dose: 5mg compared with 1mg for hair loss — to treat an enlarged prostate, a common condition that affects many men with age, causing problems with urinary flow.

That’s because reducing levels of DHT can also help shrink the prostate, stopping it pressing on the bladder and urethra.

Finasteride is, by any measure, a hugely popular drug, with more than 3.3 million prescriptions issued for prostate problems alone in England and Wales in 2017, which is double the number just ten years earlier.

But there is another side to this apparent success story — the drug’s potential side-effects.

DHT influences other male characteristics and interfering with its production can lead to sexual dysfunction, including difficulties achieving an erection, reduced desire and reduced semen.

Risk: In simple terms, it stops hair loss by reducing the conversion of the male hormone testosterone into dihydrotestosterone (DHT). High levels of DHT cause hair follicles on the scalp to shrink, leading to hair loss

Less frequent problems can include infertility, testicular pain and anxiety.

And since 2017, following a ruling by the European Medicines Agency, finasteride patient information leaflets must also now carry warnings about the risk of depression and, in rare cases, suicidal thoughts.

MSD (Merck, Sharp & Dohme Limited) which manufactures Propecia, says up to only one in 100 people is affected by sexual dysfunction, although it does now acknowledge in patient information leaflets that this can persist after coming off the pills.

In the U.S., Merck & Co has paid out more than £3 million in total to hundreds of men who have claimed side-effects have persisted after they stopped taking Propecia.

Meanwhile, growing numbers of British men say they have been affected by persistent side-effects — one of them is Ryan Clark, 52, an operations manager from North Tyneside, who says the drug has wrecked his libido and left him with reduced fertility and depression.

After taking finasteride on and off for 18 years, he says he is still plagued by side-effects, despite stopping for good two years ago.

‘I QUICKLY LOST ALL INTEREST IN SEX’

Ryan started taking finasteride after noticing a tiny bald spot on his crown. ‘I was only 31 and didn’t want to go bald at such a young age,’ he says. He had read about Propecia and thought it sounded like ‘a miracle cure’. Ryan’s GP prescribed the drug privately and he began paying £30 a month for the daily pill.

‘In terms of treating my hair loss, the drug worked brilliantly and the gaps on my crown filled in within three months,’ he says. ‘However, within weeks I lost interest in sex and my libido didn’t return. I didn’t connect it with finasteride as this side-effect was never mentioned.

‘Within three months, I began to feel anxious and to suffer insomnia. I’d always been confident, happy and positive, but suddenly I became withdrawn and irritable.’

Devastated: Ryan Clark, 52, an operations manager from North Tyneside, who says the drug has wrecked his libido and left him with reduced fertility and depression

Ryan, who married Lyndsey, 42, in 2010, went back to his GP ‘multiple times’ about his various health problems. ‘They treated each one individually,’ he says. ‘I was offered medication for sleep and depression, but I refused them.’

His list of symptoms continued to grow. ‘I developed dry skin, sore, red eyes and heart palpitations, muscle loss and weight loss.’

Then, in 2010, tests showed he had poor-quality sperm with low motility and he was told he and Lyndsey were unlikely to conceive naturally. Their son, Joshua, now six, was conceived through IVF.

Throughout all this, Ryan continued to experience symptoms. ‘I felt that people thought I was a hypochondriac,’ he says. ‘I’d see my GP, but all I got was a roll of the eyes. How I wish now I’d never been so vain about losing my hair.’

SIDE-EFFECTS THAT JUST GO ON AND ON

Two years ago, a desperate Ryan searched his symptoms online and came across post-finasteride syndrome (PFS) — a collection of symptoms that include sexual dysfunction, infertility, anxiety and depression, which persist long after finasteride is discontinued.

The side-effects may be the result of changes to hormone receptors in the body, suggests Professor David Healy, a psychiatrist at Bangor University and founder of RxISK, a pressure group that campaigns to highlight drug side-effects.

‘Finasteride doesn’t just act on the hair growth and shrink the prostate, but has effects throughout the body,’ he says.

‘I felt that people thought I was a hypochondriac,’ he says. ‘I’d see my GP, but all I got was a roll of the eyes. How I wish now I’d never been so vain about losing my hair.’

‘As with a whole bunch of other drugs, such as SSRI antidepressants and the acne drug Roaccutane, we don’t know why these effects persist in some people.’

When Ryan read about PFS, ‘suddenly everything clicked into place — I had virtually all the symptoms listed and they had all started after I began taking Propecia,’ he says.

‘There were 5,000 men, many of them from the UK, like me on a website, all describing how their lives had been wrecked by the drug.

‘I stopped taking the pills, but none of the symptoms have gone away in the two years since. In fact, I’ve developed neuropathy [nerve damage, causing pins and needles] in my hands and feet, too.

‘Yes, the patient information leaflet does mention sexual dysfunction but it doesn’t stress how serious and long-term the problems can be.’

YOUNGER MEN AT GREATER RISK

The threat that finasteride poses to fertility should be stressed to younger men, suggests Allan Pacey, a professor of andrology at the University of Sheffield.

‘I ran an andrology laboratory in Sheffield for 25 years and I would regularly come across men who had poor or no sperm,’ he says. ‘They would reluctantly admit to using anabolic steroids — which was obvious anyway because of their appearance — or taking finasteride.’

Professor Pacey explains the effect on sperm is because both finasteride and anabolic steroids lead to the shutdown of the crucial hormone produced by the brain which tells the testicles to produce sperm.

The body is fooled into thinking the testicles are working harder than they actually are because the level of testosterone in the blood is increased.

‘The data seems to show that when a man stops [taking the drugs], he recovers the ability to produce sperm, but it may take many months.’

DANGERS MUST BE EMPHASISED

Dr David Edwards, a GP in Chipping Norton and past president of the British Society for Sexual Medicine, agrees that the potential side-effects, and the fact they can be long-lasting, should be made clearer to patients.

‘If you asked the average practice nurse, pharmacist or GP about this, I don’t think they would know about the risk of side-effects such as sex problems and depression,’ he says. ‘There needs to be more education about the risks.’

Tom, 45, a former teacher from Cheshire who spoke on condition of anonymity, couldn’t agree more.

OTHER DRUGS LINKED TO MALE INFERTILITY Finasteride isn’t the only drug reported to cause sexual dysfunction. Research published in the International Journal of Risk & Safety in Medicine in 2018 identified 13 other medications that have been associated with sexual issues, such as ‘pleasureless or weak orgasm, loss of libido and impotence’. The drugs listed include antidepressants known as selective serotonin reuptake inhibitors (SSRIs), isotretinoin (the active ingredient in the acne drug Roaccutane), and 5-alpha-reductase inhibitors given for hair loss and prostate issues, a class of drugs which — as well as finasteride — includes dutasteride (brand name Avodart). Researchers who studied 300 reports of sexual dysfunction found there was overlap in some symptoms reported from the drugs. Common features included genital numbness, problems orgasming, loss of libido and impotence. These issues had knock-on effects including relationship breakdown and impaired quality of life. Researchers called for more work to establish why these drugs might cause such a wide range of sexual problems. Advertisement

He took Propecia eight years ago for only three months, but says as a result he’s lost his career and relationship and is now living with his parents and working part-time in retail.

‘My relationship crumbled under the pressure of the sexual problems and I haven’t had another relationship since,’ he says. ‘I had to give up teaching because of memory and fatigue problems.

‘It’s not the life I imagined I would be living. And I only took the pills after some guys I knew took the mickey out of a bald spot I had developed.’

His GP agreed to write a private prescription for Propecia. ‘He did mention impotence could be a side-effect, but being young I don’t think I quite understood what this meant.

‘In the third month, my libido just dropped and I started to experience erection problems. I felt incredibly tired and had memory issues.

‘I stopped taking the pills and hoped it would all stop — but it didn’t.’

Tom’s GP said the symptoms weren’t connected to the drug and said he had prescribed finasteride at a higher dose to patients with an enlarged prostate with no ill-effects.

‘I later saw an NHS endocrinologist who said the same thing, as did two more I paid to see privately. They told me I had depression, which I didn’t think was correct.

‘Four months ago, I experienced new neurological symptoms including increased anxiety, head pressure — like I had concrete inside my head — headaches, total impotence and terrible insomnia.’ Those affected say the medical profession’s refusal to acknowledge that finasteride can cause such side-effects is particularly hard to take.

Ryan says: ‘I have seen two endocrinologists who say my hormone levels are normal, and my symptoms are not connected to finasteride.’

PEOPLE TAKE THEIR OWN LIVES

The online support group Propecia Help says it has 5,000 members and that men are joining at the rate of 100 a month from across the globe. It reports that 59 suicides have been associated with the drug globally.

‘People need to be specifically warned about these side-effects so they can weigh up the risk versus the benefits,’ a spokesman told Good Health.

‘A man losing a bit of hair can’t be expected to imagine that he is risking a horrifying condition beyond current medical understanding when neither the prescriber nor the leaflet emphasises the risks sufficiently.’

Professor Healy also stresses the need for more recognition of the risks.

‘People kill themselves after taking this drug,’ he says. ‘I had a colleague who took his own life 15 years ago, so I know it happens — and so many people with the same symptoms can’t be wrong.

‘People take their own lives because of the effects of the drug, but also because they can’t get through to anyone and they are not believed.’

For men taking the drug at larger doses for an enlarged prostate, the benefits are thought to outweigh the risks.

Professor Roger Kirby, a prostate surgeon and president of the Royal Society of Medicine, says Proscar is a good treatment for older men with enlarged prostates who aren’t too concerned about potential effects on their sex life.

‘But I tend not to prescribe finasteride to younger men with benign prostate disease because of the sexual side-effects. There are alternative treatments that can be prescribed for younger men.

‘I think younger men worried about hair loss are better off having a hair transplant.’

MSD, however, emphatically defends Propecia’s safety record. ‘Propecia (finasteride) has been prescribed to millions of men worldwide since its approval, and has been the subject of extensive clinical trials, reported to regulatory agencies around the world,’ says a spokesperson.

‘The safety and efficacy of our products is paramount.

‘We continuously monitor the safety profile and update the safety information which is included in both the summary of product characteristics (intended to inform health professionals) and the patient information leaflet (or ‘packet insert’, intended for patients).

‘The potential for erectile dysfunction and depression to occur as an adverse reaction with finasteride treatment, although uncommon, is documented in both the Summary of Product Characteristics and the Patient Information Leaflet.

‘Anxiety is another potential side effect which is listed.’

For more information visit propeciahelp.com