Altitude sickness on the Everest trek: the simple rules that keep you safe
Altitude — not the walking — is the real challenge of an Everest trek. Here are the proven rules, and the warning signs, every trekker should know before 2026.
Here is the truth most first-time trekkers underestimate: the hard part of the Everest Base Camp trek is not the distance or the steepness — it is the thin air. Above 3,000 metres your body has to adapt to roughly half the oxygen it is used to, and rushing that process is what makes people sick. The good news is that altitude sickness is largely preventable if you follow a few well-proven rules.
Know the basics
- Symptoms of mild AMS: headache, nausea, poor sleep, fatigue
- The golden rule: climb high, sleep low, and ascend slowly
- Build in acclimatisation days (Namche, Dingboche on the EBC route)
- If symptoms worsen, the only sure cure is to descend
The rules that work
Acclimatisation is not optional — it is the whole game. Above about 3,000m, aim to raise your sleeping altitude only gradually each day, and take rest days where the classic itineraries put them (a good Everest trek schedules acclimatisation days at Namche Bazaar and Dingboche for exactly this reason). Hydrate hard, walk slowly, eat well, and never ignore a worsening headache. Many trekkers carry acetazolamide (Diamox) as a preventive — discuss it with your doctor. Above all, respect the mountain's timetable, not your own.
| Rule | Why it matters |
|---|---|
| Ascend slowly above 3,000m | Gives your body time to adapt |
| Climb high, sleep low | Trains the body without overnight stress |
| Take acclimatisation days | Namche & Dingboche exist for this |
| Descend if it gets worse | The one reliable cure for serious AMS |
What this means for you
You do not need to fear altitude — you need to respect it. Our Everest itineraries are built with the right acclimatisation days and guides trained to spot early symptoms, so you ascend at a pace your body can handle. Choose a properly paced trek, and the thin air becomes a challenge you are ready for, not a gamble.
Source: Travel Himalaya Nepal.
Cover photo: Nepal Trek Adventures via Wikimedia Commons (CC BY-SA 4.0).
Source: Travel Himalaya Nepal
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