But when the Bendigo resident returned to camp and took her boots off, she discovered three of her toes were purple with frostbite.

“I got back to camp… and I saw my big toe on my left foot was really purple and the next two toes were a bit purple,” Ms McMahon said.

”I knew I had to get straight down to get it treated to get the best chance of a good outcome.”

She returned to Kathmandu for immediate treatment, and as soon as she was able, flew back to Australia.

She is now receiving treatment in a hyperbaric chamber at the Alfred Hospital in Melbourne.

Doctors are hoping that this will allow them to save the majority of Ms McMahon’s left big toe.

For four hours each day, she enters the chamber.

Inside, the pressure is gradually increased to 2.5 times atmospheric pressure. 

Instead of breathing air, Ms McMahon receives 100 percent oxygen.

This increases the oxygen in her blood to around 15 times what is normal, helping her body to heal its tissue and fight infection.

Ms McMahon’s feet were frostbitten when she was forced to wait behind a traffic-jam of climbers on their way to the summit of Mount Everest.

She had been making good time on previous days, so she left the camp later than other climbers.

“After a bout an hour and a half I caught up to a mass of people, and four hours I was barely moving,” she said.

“My body didn't get moving, and my hands didn’t get cold. I noticed my feet get cold, but I kept moving them.”

After overtaking the group, she reached the peak, and returned to camp. 

Upon discovering her frostbite, she knew she had to return to Kathmandu for medical treatment immediately.

Her biggest disappointment was not being able to climb the Lhotse peak.

She had been hoping to climb that peak the next day, but knew that the consequences of pushing on would have been dire.

“It was disappointing, but… I’ve had enough time and experience in the mountains that if I’d tried to push on and climb the next mountain, I would have been losing three toes,” Ms McMahon said.

“I just climb because I love being in the mountains, I don’t really need to prove anything to anyone.”

Senior Specialist in Hyperbaric Medicine at the Alfred Hospital, Ian Millar is involved with treating Ms McMahon’s wounds.

Frostbite is the effect of damage done to human tissue when it is frozen, Dr Millar said. When the frozen tissue is rewarmed, the process happens incompletely, leaving blood supply partly blocked and causing the tissue to die.

The aim of Ms McMahon’s treatment is to save as much of her big toe as possible.

She is however, still facing the loss of several millimetres off the tip.

“What essentially happens in patients like Sam is there’s a zone in the middle that could go either way,” Dr Millar said.

“We’re trying to maximise what will survive so that she’ll have the best possible foot to walk on and probably to go mountaineering in the future.

“We’ve seen some significant visible improvement already, in this particular situation, Sam and the medical and nursing team can actually just look at the foot and see visible change after treatment.”

This isn’t the biggest challenge Ms McMahon has faced to date however.

At age 23, she had a full hip replacement.

In her first year of Unit at La Trobe she was in a bad car accident that broke her left tibia and fibula.

While recovering, she began running.

Just 800 metres into charity event ‘Run for the Kid’ she fell and broke her hip, and ended up needing a total hip replacement.

Told to give up high-impact sport, Ms McMahon took up mountain bike riding. With this she has traveled all over the world.

“For me it’s not as bad as having a total hip replacement at all,” she said.

“It may affect my rock climbing abilities, which is a bit disappointing, and there is a risk that there’ll be some permanent nerve damage there.”

An passionate mountaineer, Ms McMahon has no intention of letting the frostbite stop her climbing.

She’s already got friends sending her reams of information about a climb in Pakistan for 2019.

It was “almost surreal” reaching the summit, Ms McMahon said.

“I still don’t really feel like I did,” she said.

“You’re standing and when you look around, there’s nothing higher. The views are absolutely amazing.”

She does however plan to prepare even more for her next expedition, and wants to urge others to do the same.

Prior to attempting Everest, Ms McMahon had climbed another 8,000 metre peak to see how her body responded to the altitude.

She hopes to see others prepare as well.

“So many foreigners go and climb Everest every year...for anyone who’s going... make sure you get experience first,” she said.

“The people who haven’t climbed before and go to just tick something off a bucket list, they might be putting people at risk.”

While disappointed, Ms McMahon is matter of fact about her injury.

“The damage isn’t as bad as it could have been, and it is a risk you undertake when you’re climbing,” she said.

“Everything that happens that leads in a new direction, teaches us something new.

“If I didn’t learn anything from this, I would say it wasn’t worth it.”