Winding through lush rice paddies, alpine forests, and barren high-altitude plateaus, the Annapurna Circuit Trek is a living masterpiece carved by nature and tradition.
Starting at a humble 760 meters, this iconic trail weaves its way up to the mighty Thorong La Pass at 5,416 meters, where prayer flags flutter in the wind and the air is so thin, it feels like you’re walking in a dream.
It’s a trek of transformations. From jungle to glacier, sweat to stillness, sunrise to snowfall. But amid all this awe-inspiring beauty lurks an invisible challenge, altitude sickness.
And here’s the truth: it doesn’t care how strong your legs are, how expensive your gear is, or how many peaks you’ve conquered before. Altitude sickness on Annapurna circuit trek, specifically Acute Mountain Sickness (AMS), can strike anyone, anytime, above 2,500 meters. It can turn your life-affirming journey into a dangerous gamble if you’re not prepared.
This Annapurna Circuit Altitude Sickness Guide is your high-altitude survival kit. It’s your cheat sheet for climbing higher without crashing your health, packed with expert insights, prevention strategies, acclimatization tips, emergency protocols, and gear advice. Whether you’re trekking with a guide, solo with a porter, or through a trusted local company, this guide helps you trek smarter, safer, and stronger.
So, before you chase the clouds and cross suspension bridges into the sky, pause here. Read this. Breathe deep. And let’s make sure the only thing that takes your breath away is the view.
What Is Altitude Sickness on Annapurna circuit trek (AMS)? The Silent Climb You Didn’t Plan For
It’s not the rugged trails, the howling winds, or even the cold that catches most trekkers off guard on the Annapurna Circuit, it’s the air itself.
As you climb higher into the Himalayas, the oxygen thins. Every breath carries a little less of what your body needs to function. Your muscles tire faster, your head might pound, and suddenly, that beautiful landscape begins to blur into nausea, dizziness, and confusion. This isn’t just exhaustion, it’s Altitude Sickness, or more precisely, Acute Mountain Sickness (AMS).
AMS is your body waving a red flag, saying, “Slow down. I’m not ready yet.”
It often strikes when trekkers ascend too quickly without giving their bodies time to adapt. And while it may start with something as innocent as a mild headache or trouble sleeping, it can escalate fast if ignored.
In more serious cases, AMS can evolve into life-threatening conditions:
- HAPE (High Altitude Pulmonary Edema): When fluid floods the lungs, making each breath feel like drowning in dry air. A persistent cough, chest tightness, or shortness of breath, even while resting, are warning signs.
- HACE (High Altitude Cerebral Edema): When the brain begins to swell from lack of oxygen. Symptoms include confusion, clumsiness, hallucinations, and inability to walk straight. It’s terrifying, and it’s fatal if not treated immediately.
Both of these require immediate descent and emergency medical attention. No summit is worth risking your life.
But here’s the good news: AMS is almost entirely preventable. The key lies in knowledge, pacing, hydration, and respect for your own body’s limits. That’s exactly what this guide will help you master.
Where the Air Gets Thin: High-Risk Altitude Zones on the Annapurna Circuit
Not all parts of the Annapurna Circuit are created equal, especially when it comes to oxygen.
While the trail starts low in lush river valleys, it gradually snakes its way into the high Himalayas, where the air grows thinner and your body’s margin for error shrinks.
Altitude sickness doesn’t strike everyone, but when it does, it often happens in the same places.
Here’s where trekkers are most vulnerable, the altitude danger zones where you’ll need to slow down, listen to your body, and maybe take an extra day (or two) to let it catch up:
Manang (3,540m): The Acclimatization Capital
This charming village nestled beneath glacier-carved peaks is more than just scenic, it’s a lifeline. Manang is your best chance to stop, rest, and give your lungs a chance to adjust before pushing higher. Smart trekkers never skip at least one acclimatization day here, and the wise add two.
Pro tip: Use the time to hike to Gangapurna Lake or Ice Lake for a “climb high, sleep low” strategy that aids acclimatization.
Yak Kharka (4,020m): Gentle Ascent, Hidden Risk
It may look peaceful with yaks grazing and prayer flags fluttering, but don’t let Yak Kharka fool you. You’re now above 4,000 meters, and your oxygen levels have dropped to about 60% of what they were at sea level. Headaches, insomnia, and fatigue often begin here.
Thorong Phedi (4,450m): The Last Safe Haven
Often used as the final overnight stop before the big push to Thorong La Pass, this is where your body is under peak stress. It’s tempting to rest briefly and push on, but if you’re feeling unwell, spending a night at High Camp (4,880m) could make symptoms worse. Know when to pause, and when to turn back.
Thorong La Pass (5,416m): The Thin-Air Challenge
This is the crown jewel, and the highest point, of the Annapurna Circuit. With dazzling views and the thrill of being on top of the world, it’s also where the air is at its most unforgiving. Here, every breath is a decision. Many trekkers start this climb in the dark hours of early morning to avoid high winds and harsh sun, but that also means colder temperatures and extra strain.
Don’t race to the top. This is where AMS turns serious if you’re not fully acclimatized.
Altitude Sickness Doesn’t Care About Your Timeline
Trekkers who try to compress the itinerary, skip rest days, or push through symptoms are the ones most often affected. Altitude sickness follows no rules, but it does follow speed. The faster you ascend, the more vulnerable you become.
Respect these zones, listen to your body, and remember—getting there healthy is more heroic than getting there fast.
When Your Body Starts to Whisper: Symptoms of Altitude Sickness You Can’t Ignore
Altitude sickness doesn’t arrive like a storm. It sneaks in quietly, one skipped breath, one restless night, one strange headache at a time.
On the Annapurna Circuit, where your days are filled with panoramic wonder and physical exertion, it’s easy to overlook the first quiet warnings from your body. But knowing the early signs of Acute Mountain Sickness (AMS) could be the most important thing you carry in your backpack.
Common AMS Symptoms: The Subtle Signs That Signal Trouble
Acute Mountain Sickness (AMS) often starts out as something that feels manageable, a bit of a headache, a little fatigue. But at high altitude, small discomforts can escalate fast. These symptoms usually appear within 6 to 24 hours after gaining elevation, especially above 2,500–3,000 meters.
| Symptom | What It Feels Like |
| Headache | A dull throb that gets worse at night, with movement, or when bending over |
| Fatigue | That bone-deep exhaustion you can’t shake, even after resting |
| Nausea or Vomiting | A queasy stomach, skipped meals, or sudden repulsion to food |
| Dizziness | Feeling like the earth just swayed beneath you |
| Insomnia | Tired but wired, tossing and turning while your heart races |
| Loss of Appetite | Food in front of you, but no desire to eat, even after a long day’s trek |
If you feel two or more of these symptoms, especially after gaining altitude, stop ascending immediately. Give your body time to adjust.
When It Turns Serious: The Red Zone
Sometimes, altitude sickness evolves into dangerous conditions that can’t be ignored or toughed out. These require emergency descent and in many cases, helicopter evacuation.
HAPE (High Altitude Pulmonary Edema)
Your lungs begin to drown in fluid. Breathing becomes a struggle, every gasp more shallow than the last.
- Persistent dry or frothy cough
- Shortness of breath, even while sitting still
- Tightness or heaviness in the chest
- Gurgling or rattling sound in lungs
- Blue lips or fingernails (lack of oxygen)
HACE (High Altitude Cerebral Edema)
Your brain swells from the lack of oxygen, and things get terrifying fast.
- Severe headache that won’t go away, even with meds
- Confusion, slurred speech, or disorientation
- Staggering like you’re drunk, loss of coordination
- Hallucinations or strange behavior
- Inability to walk in a straight line
If you or someone you’re trekking with shows these signs, don’t wait. Descend immediately and call for evacuation if possible.