Altitude Sickness: Symptoms, Prevention, and Treatment

Altitude sickness (Acute Mountain Sickness, or AMS) is the biggest risk on Nepal’s high-altitude treks. Here’s what you need to know.

What Causes Altitude Sickness?

At altitudes above 2500m, the air pressure drops and you take in less oxygen with each breath. Your body needs time to acclimatize. If you ascend faster than your body can adapt, AMS develops.

Symptoms

Mild AMS: Headache (the hallmark symptom), nausea, fatigue, shortness of breath, loss of appetite, difficulty sleeping.

Severe AMS (HAPE/HACE): Severe headache unresponsive to painkillers, vomiting, ataxia (loss of coordination — the “drunk walk”), confusion, blue lips, gurgling breath, coughing pink froth. These are medical emergencies.

Prevention

• Ascend slowly: above 3000m, gain no more than 300-500m of sleeping altitude per day.
• Take acclimatization days every 1000m gained.
• Climb high, sleep low: day-hike higher than your sleeping altitude.
• Drink 3-4L of water daily.
• Eat high-carbohydrate meals (garlic soup is a Himalayan staple).
• Avoid alcohol and sleeping pills.
• Consider Diamox (acetazolamide) 125mg twice daily above 3000m.

Treatment

For mild AMS: Stop ascending. Rest, hydrate, take ibuprofen. If symptoms worsen, descend 500m or more.

For severe AMS: Descend immediately — at least 1000m. Do not wait for morning. If you can’t descend, use supplemental oxygen and a Gamow bag if available. Take Dexamethasone for HACE (8mg initial, 4mg every 6 hours) and Nifedipine for HAPE.

Carry a Pulse Oximeter

A fingertip pulse oximeter (we rent these for USD 0.50/day) lets you track your blood oxygen saturation. Normal at sea level is 95-100%; at 4000m, 80-90% is acceptable; below 80% is concerning.

The Golden Rule

Never ascend with symptoms of AMS. If you feel worse, descend. No mountain is worth your life.