The mountaineering community is split on the use of xenon gas. Photo: Mission: Everest
Four British men are currently on the slopes of Mount Everest trying something that has never been done: to travel from London to the top of Mount Everest and back in a week. They’ve taken doses of xenon gas – a controversial substance not widely tested in mountaineering – to give their bodies a physical advantage and blow past other expeditions on the mountain.
The previous London to Everest and back record is 21 days, while the fastest sea level to Everest and back record is 14 days. In contrast, typical expeditions take six to eight weeks to acclimate and summit the mountain. Al Carns, Garth Miller, Kevin Godlington, and Anthony Stazicker, British Special Forces veterans climbing under the mountaineering company Furtenbach Adventures, strive to shave that record down to a week in the name of charity for fellow veterans.
To accomplish the feat, they’ve been sleeping in hypoxic tents since early 2025 and exercising in masks to simulate the low-oxygen environment of the Himalayas. However, to further aid in reducing their acclimation time on the mountain, on May 5, under medical supervision, the four inhaled a “sub-anesthetic concentration” of xenon gas mixed with oxygen.
Xenon gas was discovered in the 1880s and used as an anesthetic. It’s shown to increase the body’s production of the protein erythropoietin, increasing red blood cells and hemoglobin, which, in theory, could mitigate the effects of altitude sickness.
The treatment was conducted by the physician Michael Fries. According to Fries’ protocol, the strongest effects of the dosage peak 10 to 14 days later, lasting an additional 10 to 14 days before it wears off. Fries doesn’t reveal all of his methodology for proprietary reasons.
Lukas Furtenbach, the mountaineer who started Furtenbach Adventures, has tested it on himself before climbs around the world, including Everest and Aconcagua in South America. The results are promising, although he notes that he also used hypoxic chambers ahead of the trips, so it’s hard to isolate the true effects of the xenon gas. Furtenbach is among 15 subjects who have undergone the treatment with Fries. Thus far, Fries says the results have been “impressive.”
The xenon gas-powered summit attempt currently underway could have lasting implications on mountaineering, depending on the result. Naturally, it’s courted controversy and created a divide in the mountaineering community.
Caroline Gleich, a professional ski mountaineer who has climbed Everest, is open to Furtenbach’s innovative approach.
“One of the most beautiful things about the mountains is the freedom they offer — freedom from distractions, freedom to test the limits of our minds and bodies,” Gleich told me. “For as long as people have been climbing, we’ve looked for ways to push a little further, go a little higher. The use of xenon gas is a fascinating development in that tradition. As long as climbers are transparent and it doesn’t put others at risk, I see it as part of the broader human experiment in performance and adaptation.”
“I spent 40 days on Everest, and I’ll always cherish that time,” Gleich added. “But not everyone has the privilege or time to spend six to eight weeks on a mountain. If this new method proves safe and effective, it could fundamentally change our understanding of acclimatization, endurance, and what’s possible at extreme altitude.”
Others are more skeptical.
The International Climbing and Mountaineering Federation put out a statement cautioning against xenon gas, warning that there is no evidence the gas improves performance and that inappropriate use can be dangerous. The World Anti-Doping Agency has had xenon gas on its list of banned substances since 2014.
Zahan Billimoria, a Wyoming-based mountaineer who trains and guides others in the mountains, thinks there is a fine line between racing to the top of a summit, and skipping the full experience.
“I get it, we all want to go up and down, in and out, faster,” Billimoria told The Inertia. “But when the mountains become just another place to rack up accolades and check boxes, I think we are missing the plot. What I think we need is the experiences that come with being ‘on the journey.’ It’s the process, the work, the uncertainty, and the personal transformation that happens through it all. You can shortcut your way to the summit, but you can’t shortcut the real gift of being in the mountains…as Jeremy Jones says, ‘The journey is the reward.’”
Alan Arnette, an experienced mountaineer turned leading Everest blogger, said he trusts Furtenbach’s expertise, but he’s “not a fan” of the potentially performance-enhancing use of the gas on Everest.
However, Furtenbach defends his experimentation principally as a safety-enhancer that can protect brain tissue at high altitudes, not as a performance-enhancer.
“…we think the less time you spend on the mountain, the safer the climb will be, and in a dangerous environment like Mount Everest, this is very obvious,” said Furtenbach.
With the British climbers currently pushing for the summit, we’ll soon have the results of one more xenon gas case study. If they are successful, Fries might have an increase in demand for his services.
