Altitude sickness can affect anyone above roughly 2,500 m, regardless of age or fitness. On the Everest trail you pass through the altitudes where it is most common, so everyone should know the warning signs. This page gives general information, not medical advice. Talk to a doctor who knows high altitude medicine before you go.
Mild symptoms
Acute mountain sickness often begins with a headache, along with nausea, loss of appetite, dizziness, unusual tiredness and poor sleep. Mild symptoms can improve with rest at the same altitude, extra fluids and simple pain relief, but you should not climb higher until you feel well.
Warning signs that need action
- A headache that gets worse or does not respond to simple pain relief.
- Repeated vomiting.
- Loss of balance, stumbling or difficulty walking in a straight line.
- Confusion, unusual behaviour or extreme drowsiness.
- Breathlessness at rest, a persistent cough, or a wet or bubbling sound in the chest.
These can point to serious high altitude cerebral or pulmonary conditions. The standard response is to descend promptly and seek medical help, even if it is the middle of the night.
How to reduce your risk
- Ascend gradually and include scheduled rest days.
- Walk at an easy pace that lets you talk.
- Drink fluids steadily through the day and avoid alcohol at altitude.
- Do not climb higher while you still have symptoms.
- Tell your guide or companions early if you feel unwell.
Medication
Some people discuss preventive medication with their doctor before the trip. This should be a conversation with a qualified medical professional about your health history, not something decided from a website.
Rescue and descent
If someone worsens, going down is the treatment. Helicopter evacuation may be needed, which is why insurance that covers it is important. Your guide should have a clear plan and a way to communicate with the nearest health post or rescue service.
Why it happens
As you climb, the air pressure falls and each breath contains less oxygen. Your body responds by breathing faster, producing more red blood cells and adjusting how it uses fluids, but these changes take days. Problems arise when you go up faster than the body can adapt. This is why the same person can feel fine at 3,500 m after a rest day and unwell at the same height after a rapid ascent.
Who is more at risk
Anyone can be affected, and past experience is not a guarantee. People who have had altitude sickness before, who ascend quickly, who travel straight from sea level without an easy first days, or who are dehydrated or ill with a chest infection are more likely to have trouble. Age and fitness are poor predictors, and young, strong trekkers are often caught out because they keep pace with the fastest in the group.
Looking after each other
On the trail, honesty is the best safety tool. Report headaches, nausea, dizziness or unusual breathlessness to your guide as soon as they appear, and do not hide symptoms to avoid slowing the group. Check on your companions too, especially in the evening, because confusion and unsteadiness can be easier for others to notice than for the person affected. If a friend seems withdrawn, clumsy or irritable without explanation, tell the guide.
A simple daily routine
- Drink steadily through the day, aiming for pale urine rather than counting litres.
- Eat regular carbohydrate-rich meals even if appetite is poor.
- Walk slowly enough that you can speak in full sentences.
- Avoid alcohol and sleeping tablets unless advised by a doctor.
- Check in with yourself each evening: headache, appetite, sleep, energy.
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Excerpts from guest reviews of Himalayan Wonders, our parent company, on Tripadvisor.
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