More than a million people using weight-loss jabs could be at risk of invalidating their travel and health insurance amid widespread confusion over whether using them should be listed as a medical condition.

Some 26 per cent of 1,000 UK adults polled by the market researcher Consumer Intelligence said that they did not know how they would classify the use of drugs such as Mounjaro, Ozempic or Wegovy when buying cover.

Only 24 per cent said that they would classify them as medical treatments for health conditions, while 11 per cent said that they would call them cosmetic treatments like botox, and 10 per cent that they were lifestyle tools.

What to do now Mounjaro’s hiking its prices, by an obesity expert

Insurers normally require consumers to disclose any pre-existing medical conditions when they buy insurance and their cover can be invalidated if they have not, even if they make a claim that has nothing to do with that condition.

Ian Hughes, chief executive of Consumer Intelligence, said that the confusion over how weight-loss jabs should be described could leave people out of pocket if they had to make a claim.

He said: “This confusion isn’t academic — it has real consequences for millions purchasing travel and health insurance. When a quarter of the population doesn’t know whether their medication counts as a pre-existing condition, we’re seeing a perfect storm for claim disputes and coverage gaps.”

About 4.75 million single-trip travel insurance policies were bought in 2022, according to the latest figures from the Financial Conduct Authority, the City regulator, along with 2.09 million annual European policies and 1.86 million annual worldwide policies.

Consumers already regularly fall foul of insurance small print when making claims, especially when it comes to travel insurance. About 27 per cent of claims on single-trip policies were rejected in 2022, the FCA said, compared with 24 per cent of home insurance claims, 5 per cent of pet insurance claims and less than 1 per cent of motor insurance claims.

The Financial Ombudsman Service, a free disputes body where consumers can complain about financial firms, has had 8,366 complaints about travel insurance since the start of 2023-24. Claims being declined was one of the biggest drivers of complaints.

Some UK insurers, such as Admiral, have added specific sections on their websites over the past year about weight-loss jabs due to their popularity, to warn consumers that they must declare that they use them when buying cover. Normally this would require consumers to detail the condition that any drugs were prescribed to treat.

About 1.5 million people in the UK now take drugs such as Mounjaro, Ozempic and Wegovy to deal with conditions such as obesity and diabetes. These drugs, a type of appetite suppressant known as GLP-1 agonists, have been approved on the NHS over the past year for those with a high body mass index, subject to their prescription by specialist weight-management services. They are also available on prescription from private clinics and pharmacies.

Mounjaro and Wegovy patients ‘need support for a year after treatment’

While consumers need to disclose the use of these drugs, they, like any other pre-existing conditions, can lead to higher premiums or an insurer refusing to offer cover. The comparison site GoCompare said on average someone with a pre-existing condition paid £5 a day on average for a single-trip policy.

That was £2 more than someone without, although its averages include everything from mild asthma to cancer, so someone who disclosed they were taking medication for obesity, high blood pressure or diabetes could see their premiums much higher. Hughes warned that “treating all GLP-1 usage as pre-existing conditions potentially prices out millions of customers” from insurance.

The Association of British Insurers said: “You should disclose any pre-existing medical conditions, as well as any prescribed medication or treatment. The industry continues to stress the importance of disclosing pre-existing medical conditions and if you’re unsure of what to declare, you should contact your insurer directly to check.”