Millions of Brits with a common condition were today warned that drugs to treat them could trigger an unexpected and bizarre sexual side effect.
The medicines — known as dopamine agonists — interact with parts of the brain that control movement, helping to ease restless leg syndrome, which is thought to impact one in 10 people in the UK.
They are also prescribed for Parkinson’s disease — a neurological condition that affects movement, and blights some 150,000 Brits.
Yet, more than a dozen women have now claimed the drugs, such as ropinirole, saw them develop compulsive gambling and sex addictions.
One told investigators how she began leaving her house in the early hours of the morning, despite having a partner, to cruise the streets for sex wearing just a transparent top and jacket.
Another said they felt compelled to gamble and accumulated debts of more than £80,000.
A previous report by drugs firm Glaxosmithkline (GSK) shows it learned of the link between such medicines and what it described as ‘deviant’ sexual behaviour in 2003.
The ‘unusual urge to gamble or increased sexual urges’ is also listed as a general warning in the patient information leaflets, tucked inside ropinirole.
More than a dozen women have now come forward claiming the drugs, such as ropinirole, saw them develop compulsive gambling and sex addictions
Graphic courtesy of the Center for Vascular Medicine. It shows the various sensations that a person with RLS feels as they try to fall asleep
However, doctors did not warn them about these serious side effects that led them to seek out such risky sexual behaviour, the women said.
One, known only as Claire, told the BBC she first developed restless leg syndrome during her pregnancies and often suffered sleeplessness and a crawling sensation under her skin.
After the condition persisted once she’d given birth she was prescribed ropinirole but claimed she was not told of any of the drug’s side effects.
While her symptoms subsided, after a year on the medication she began to experience unprecedented sexual urges.
‘The only way I could describe it is it was just deviant,’ she said.
‘There remains an element in your head that knows what you’re doing is wrong, but it affects you to the point that you don’t know you’re doing it.’
Claire also recalled leaving her house in the early hours of the morning to cruise for sex, flashing her chest at any man she could find.
She did this regularly, she said, and in increasingly dangerous locations, despite having a partner.
Another woman, known only as Sue, said she was prescribed two different dopamine agonist drugs without being warned of compulsive behaviour side effects She racked up debts totalling £80,000
After finally coming off the medication, the urges disappeared almost immediately she said, adding she felt ‘shame’ and was ‘mortified’ by the danger she placed herself in.
Another woman, known only as Sue, said she was prescribed two different dopamine agonist drugs without being warned of compulsive behaviour side effects on either occasion.
She claimed she even told her doctor of her recent gambling habit before the second drug was prescribed, before racking up debts totalling £80,000.
‘The effect on my family was horrific — it was life-changing money to lose,’ she said.
‘But at the time I didn’t know it was no fault of my own.’
Earlier this year, one patient with restless leg syndrome hit by the side effect also told The Mail on Sunday that he developed a serious gambling addiction and lost £100,000.
The married father of two, 54, who asked to be referred to only as Mr Wilson, had never placed a bet before he was prescribed a low dose of the dopamine agonist ropinirole in 2014.
After his symptoms persisted his dose was gradually increased over two years.
One woman has also told how she began leaving her house in the early hours of the morning, despite having a partner, to cruise the streets for sex wearing just a see-through top and jacket after being prescribed ropinirole
While they eventually subsided, this was when his other problems began.
‘I remember seeing an advert on my computer for an online slot machine, which said it offered better odds than the lottery. I thought, well, I do that so why not give it a go,’ he said.
‘It started small with bets and I was winning a little. But when I started losing, I would chase my losses. That’s when it spiralled and I was betting daily.
‘It really drove a wedge between me and my family. I was incredibly secretive about what was going on but my personality started to change and I was becoming aggressive.
‘I took out two loans, maxed credit cards and nearly lost all of our savings. I was betting at every opportunity, even while I was at work. It nearly cost me everything.’
According to the UK medicines spending watchdog the National Institute for Health and Care Excellence, impulsive behaviours, including gambling and increased sex drive, are thought to affect between 6 to 17 per cent of restless leg syndrome patients taking them.
In a statement, GSK told the BBC that Ropinirole had been prescribed for more than 17 million treatments and undergone ‘extensive clinical trials’.
It added the drug had proven to be effective and had a ‘well-characterised safety profile’.
‘As with all medicines, [it] has potential side effects and these are clearly stated in the prescribing information,’ it said.
According to the BBC, a class action was brought against GSK in 2011 by four sufferers of Parkinson’s disease, who claimed ropinirole led to gambling debts and broken relationships.
They also complained that despite a link between such behaviours and the drug having been established in medical studies, GSK had failed to include any warnings in its product literature until March 2007.
The class action was settled but GSK denied liability.
Last December, Philip Stevens, 66, from Ringwood, Hampshire, also won £70,000 compensation after developing a gambling addiction while taking ropinirole for restless leg syndrome.
The condition leads to an unpleasant ‘crawling’ sensation in the legs, mostly at night, and an almost irresistible urge to move them.
