I hiked a mountain in the Andes to celebrate my 40th birthday. The hallucinations and violent vomiting that followed had not been part of the plan.

12.08.2024 - 06:01 / insider.com / Lake Titicaca

The condors appeared at 5,000 meters. They were not real.

I got altitude psychosis a few hundred meters from high camp as I scaled the frigid face of Huayna Potosi, the ninth-highest mountain in the Bolivian Andes.

My optimism, determination, and the sugar high from my last frozen-solid Snicker's bar had all but faded into a combination of low-key anxiety, aching muscles, and vertigo by the time I started hallucinating birds with giant geometrically patterned wings alighting gently in on the ice-slicked rocks around me.

With the help of a phenomenal local guide and a lot of luck, I made it back down the mountain. I still do multi-day treks at altitude in the Andes and Caucasus mountains, but I follow some hard rules to keep myself safe.

I first glimpsed Huayna Potosi, a mountain near Bolivia's La Paz and El Alto, when I sailed across Lake Titicaca, the massive freshwater lake linking Peru and Bolivia. I remember thinking, naively, "I can climb that," and set forth to summit on my 40th birthday.

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I climbed too quickly, without ample preparation or acclimation, and tamped down the effects of your garden-variety altitude sickness, like nausea, headaches, and fatigue with a combination of cold-brewed coca leaf tea, water, acetaminophen, and sugar.

I didn't realize I was sick until it was far too late; I started hallucinating and violently vomiting as I tenuously made my way up to high camp, crampons skidding and slipping off the packed ice as exhaustion and confusion set in.

Thanks to my excellent guide, I made it to high camp and spent the night in an orange geodesic dome perched on Potosi's precarious eastern side. I didn't sleep a wink. Instead, I spent all night prying open the triangular door of the dome with a screwdriver, vomiting spectacularly on the rocks outside, and marveling at how gorgeous the stars looked at that height.

High-altitude psychosis generally occurs at heights of 7,000 meters or higher, although it can strike hikers trekking at lower altitudes. Once referred to as mountain madness, it's a uniquely terrifying ailment that manifests itself in hyper-intense hallucinations and disappears once you descend.

Although high-altitude psychosis doesn't always happen in tandem with altitude sickness, my doctor speculated that my experience had a lot to do with not acclimatizing properly, overestimating my abilities, and minimizing the effects of altitude sickness through a constant regimen of over-the-counter medication and natural remedies, like coca tea.

Frontiers in Psychiatry noted that while episodes of psychosis during exposure to high altitude are frequently reported, it has still not been assigned to medical diagnoses.

I would have been in serious trouble if not