London has a frostbite plague. What's behind it?

The cases first appeared in late 2024, each following the same mystifying pattern. A patient would present in A&E with a large wound: a circular shaped cold burn cutting deep into the fatty tissue on their inner thigh. But what was even stranger was that none of the victims would explain what caused it. In fact, many had waited days before coming to A&E, even as the sore festered and infection set in.

The injuries looked like frostbite, something doctors would only very rarely see among the city’s homeless during the most extreme winters. But these cold burns would appear year round, even in the middle of summer heat waves. And every case would end the same way: surgery to cut away the dead flesh, skin grafts and permanent scars for the victims.

After the first trickle, the last two years have seen these strange injuries become commonplace in London’s hospitals. Nicole Lee, an intensive care nurse at Chelsea and Westminster Hospital and the chair of the British Burns Network, says every burns unit in the south-east of England she oversees, even the ones in tiny cottage hospitals, are seeing at least one of these patients a week. For the bigger hospitals in London, that can sometimes rise as high as four or five.

The Londoner has spent the last few days looking into this new scourge, which has never been publicly reported on before. The cause of these mysterious wounds, it turns out, is nitrous oxide, a drug the government outlawed in 2023. And this spate of cold burns is exposing how its use, now driven underground by the crackdown, has spiralled into a “monster” of society’s own making.