Three years ago I lived in Arequipa with a Swiss fella who loved climbing mountains. He organized a group to climb Misti. It’s a 2-day excursion. You camp at the halfway point so your system acclimates to the altitude.
On day 2 the Swiss fella couldn’t continue. He had altitude sickness and stayed at camp. He’d climbed several mountains in the Alps, and he was fit. He believes he couldn’t go on because he didn’t bring any coca.
I, one the other hand, brewed 2 liters of coca tea to drink in addition to water on the recommendation of a Peruvian who’d mounted Misti twice. It was a bitch carrying a 2-liter of coca AND a 2-liter of water in addition to all my other shit, but I never even noticed the altitude. Only the cold.