Acute Mountain Sickness (AMS) is the body's protest at climbing faster than it can adapt to thinner air. It can affect anyone — fitness is no immunity — which is why understanding it beats fearing it.
What it feels like
The classic early signs: a persistent headache, loss of appetite, nausea, unusual fatigue and disturbed sleep, typically appearing 6–12 hours after reaching a new altitude above ~8,000 ft. Think 'worst hangover of your life' — that's textbook mild AMS.
The rules that keep it mild
Climb high, sleep low; ascend gradually (our itineraries build this in); drink 4–5 litres a day; skip alcohol entirely; and never ignore a headache that paracetamol doesn't touch. Report symptoms to your trek leader early — nobody has ever been judged for it, and early reporting is what keeps small problems small.
How we monitor every trekker
Twice-daily oximeter and pulse checks on every TrekNova batch, recorded per trekker. Falling oxygen saturation plus symptoms triggers our protocol: stop ascent, assess, and if symptoms persist — descend. Descent is the cure; everything else only buys time.
When it's serious
Confusion, breathlessness at rest, a wet cough or stumbling gait are signs of severe altitude illness (HACE/HAPE) — rare on our sub-16,000 ft trails, but our leaders carry oxygen and are trained for immediate evacuation. This is precisely why you trek with a professional team.
