What’s wrong with using Xenon to climb Everest?

Reaching the top of the world and returning to London within a week without so much as stopping for a coffee in Kathmandu sounds like the stuff dreams are made of. But on 21 May 2025, four former members of the British special forces turned this dream into reality when they stood on the summit of Mount Everest four days and 11 hours after leaving the UK. Their secret was to inhale Xenon two weeks prior to the climb, a gas well known to anaesthetists, but so far unheard of in mountaineering.

‘Although Xenon has worked well in clinical studies, it is very rarely used for patients in the UK. It is expensive and complex to administer with no significant benefits over established agents,’ says Dr Mike Grocott, a professor of anaesthesia and critical care medicine at the University of Southampton.