Insurers are now processing claims from more than 3,000 British travellers per week who require emergency medical care while abroad, according to the Association of British Insurers (ABI).
While the average travel insurance claim is just over £700, more serious accidents requiring extensive medical treatment and repatriation costs can reach £500,000, while government estimates put the average price of a UK house at £211,000.
Medical insurance claims can be especially steep from the US, which has some of the highest treatment and medication costs of any country and was the most frequently visited destination by UK tourists this spring.
An insurer recently paid a medical bill of £322,000 for treating a swollen blood vessel in the brain, while a treatment for an abscess in the abdomen cost £101,000.
Figures from travel insurer Staysure have estimated the US is the most expensive country to fall ill abroad in, with the average medical claim coming in at £5,533, followed by Canada in second place at £4,356 and India at £3,423.
Elsewhere, the complexities of needing transportation to the nearest medical facilities can make ocean travel health claims expensive – a Caribbean cruise heart attack sufferer's bill came to £92,000.
British travellers whose expenses were covered by travel insurance have also faced sums of £300,000 after a fall from a waterfall in Thailand, £40,000 to cover a Dengue fever sufferer's treatment in Indonesia and £31,000 to treat a broken leg in Nepal.
"While most travellers enjoy trouble-free holidays, falling ill abroad can be very stressful without the added worry about how you will pay for potentially very expensive medical bills," Mark Shepherd, ABI's manager for general insurance, said.
"Travel insurance should not be an after-thought, but the first thing you arrange after booking any overseas trip."
However, insurers might be processing fewer claims if the UK's "staycation" domestic tourism industry continues to boom.
The drop in Sterling since the Brexit vote will add momentum to the domestic tourist economy, business recovery group Begbies Traynor's has said, driving further growth in a sector that was already in a state of "improving financial health" in the three months leading up to the referendum.