Some patients might turn to unsafe sex and gambling, what experts call “impulse control disorder.”

Slimmers were warned today that weight loss injections could trigger an unexpected and bizarre side effect: reckless behavior.

Groundbreaking injections such as Ozempic and Wegovy, hailed by Elon Musk and Jeremy Clarkson, have been proven to help people lose up to two stone.

But experts say the treatment could cause some users to act “out of character,” engage in unsafe sex, compulsively gamble or even make rash, major life decisions, like filing for divorce. .

They believe that changes in dopamine levels in the brain, possibly linked to the injections, could be behind the problem, contributing to the ever-growing list of disadvantages.

The London researchers say patients should be warned about the potential for these bizarre reactions, known collectively as impulse control disorder, before starting medication.

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Professor Raymond Playford, an expert in molecular medicine at the University of West London and co-author of the study, told MailOnline: ‘We have patients who suddenly ask for divorce or break up from what seemed like relationships stable and change family situation, such as moving at short notice.

“We have not observed excessive gaming or sexual activity in patients so far, but we would not be surprised if it happened.”

Writing in the Quarterly Journal of Medicine, the researchers said they do not know exactly why medications can cause this effect.

But Professor Playford added: ‘Risk behaviors due to impulsivity are also associated with side effects of Parkinson’s drugs.’

Weight loss injections “share the common mechanism of influencing dopamine levels in the brain,” he added.

“It is well established that hypersexuality and excessive gambling are associated with evodopa use.”

Dopamine is nicknamed the “happiness hormone” for its role in feelings of happiness, pleasure and reward.

Research has shown that at higher levels, people become overstimulated by everyday activities such as shopping, playing, eating or making love, and then find themselves essentially “addicted”: having to repeat the behaviors over and over again. again, seeking to replicate that initial thrill.

Currently, impulse control disorder is listed as a potential side effect in patient information leaflets for Parkinson’s medications such as levodopa.

However, no such warning appears on the weight loss vaccine brochures.

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Professor Playford told MailOnline: ‘We advise doctors to also warn patients to watch out for ‘out of character’ or unusual urges that have a personal cost or repercussions – for example divorce – and to ‘take extra care’ step back” and ask yourself if this is a problem. wise decision.

“It can also be helpful if they share that they are starting (medications such as Ozempic) with a loved one or close friend, so they can give a heads up if they notice anything unusual .

“This warning should allow patients and doctors to reflect and determine whether decisions made by some patients are out of character and riskier than expected.”

“If they’re not aware that it’s a possibility, they don’t make an association.”

Semaglutide (sold under the names Ozempic and Wegovy) and tirzepatide (Mounjaro) have been hailed as a monumental breakthrough in the war against obesity.

The pens, taken once a day, mimic a hormone called GLP-1 and trick the brain and body into thinking it is full, thereby reducing appetite.

Trials show that semaglutide, made by the Danish company Novo Nordisk, helps users lose up to 33 pounds (15.3 kg) on ​​average in about a year.

Side effects of the injections, including bloating, nausea and acid reflux, have long been noted by the government’s medicines watchdog, the National Institute for Health and Care Excellence (NICE) .

A growing number of Ozempic users on social media have also complained of being left with gaunt facial features, sagging “melted candle” skin, “empty” breasts and hair loss – which are not not considered a direct side effect of the drug but a consequence. spectacular thinning.

The analysis suggests the cost of tackling the knock-on effects of vaccines on the NHS could be more than £100m a year.

Others, meanwhile, have warned of bad breath and even sexual dysfunction.

The latest NHS data shows that 26 per cent of adults in England are obese and 38 per cent are overweight but not obese.

Experts have highlighted a lack of exercise and a poor diet high in ultra-processed foods as the main factors behind the UK’s obesity epidemic.

Wegovy was approved by the NHS last year, specifically for weight loss.

But the eligibility criteria for people wanting to get the drug on the NHS – for the standard prescription rate of £9.90 in England – are strict.

Mounjaro was received the green light from NICE for NHS to be used in September for patients with type 2 diabetes who are not controlling their condition.

It is not yet used by health services for obesity.

But in February it was made available privately in Britain, with clinics charging around £40 for a week’s supply.