Altitude sickness can affect anyone above roughly 2,500 m, regardless of fitness. Early signs are headache, nausea, dizziness and poor sleep. Climb gradually, include rest days, drink fluids and report symptoms early. If symptoms get worse, descend. This page is general information, not medical advice, so talk to a doctor who knows altitude medicine before you go.
Symptoms to know
Mild altitude illness usually starts with a headache, plus nausea, loss of appetite, dizziness, unusual tiredness and broken sleep. These can ease with rest at the same height, but do not go higher until you feel well.
Serious signs need action at once:
- A headache that worsens or ignores simple pain relief.
- Repeated vomiting.
- Stumbling, poor balance or trouble walking in a straight line.
- Confusion, odd behaviour or heavy drowsiness.
- Breathlessness at rest, or a wet cough.
These can point to dangerous conditions affecting the brain or lungs. Tell your guide immediately and do not ignore a friend who seems different.
Ascent rate and rest days
The main protection is a slow rise. Above about 3,000 m, most guidance is to increase your sleeping altitude gradually and add rest days at intervals. A common habit is to climb high and sleep low, walking up for a view and returning to sleep lower.
Routes like our 14 day Everest Base Camp itinerary build in acclimatisation days for this reason. Do not rush early days because you feel strong, since altitude effects often show later. A spare day in your plan gives you a buffer for weather, illness or slow adaptation. Younger, fitter people are not safer, and sometimes they climb too fast. Walk at a pace where you can speak in short sentences.
Hydration, food and sleep
Drink water steadily through the day, enough that your urine stays pale. Dry mountain air and extra breathing cause fluid loss, and dehydration can mimic or worsen symptoms. Hot tea and soup count toward your fluids.
Eat regular meals even when appetite is poor, because the body needs energy. Carbohydrate rich food such as rice, noodles and potatoes is easy to find in teahouses. Limit alcohol, which can affect sleep and judgement. Sleep may be broken at altitude, with odd breathing patterns at night, and that is common. If you wake with a pounding headache or feel breathless at rest, tell your guide in the morning, or earlier if it is serious.
Medication myths and medical advice
There is no tablet that lets you ignore the rules of gradual ascent. Some people use medication to help prevention, but whether that suits you depends on your health, allergies and other medicines, so discuss it with a doctor before you travel. We do not give doses here.
Myths to drop: that fitness protects you, that garlic soup or a special drink cures it, that you can push through a bad headache, or that symptoms always fade overnight. Painkillers may ease a headache but do not treat the underlying cause. Mild symptoms can be managed by resting, and anything that worsens needs descent. Carry a small first aid kit and your own prescriptions.
When to descend and how guides monitor
Descent is the most reliable treatment. If symptoms worsen, if you cannot walk normally, or if you have confusion or breathlessness at rest, go down, even at night, and get medical help. Do not wait for morning if the signs are serious.
A good guide checks each trekker daily, asking about headache, appetite and sleep, watching balance and mood, and noting how people look at breakfast. Some teams carry a pulse oximeter, which gives a rough reading but is only one clue. Honest reporting is your part. Ask your operator how evacuation works and confirm that your insurance covers trekking at your maximum altitude and helicopter rescue.
Common questions
At what height does altitude sickness start?
It can begin above roughly 2,500 m, though people vary. Risk rises with height and speed of ascent, so a gradual itinerary with rest days is the best protection.
Can fit people get altitude sickness?
Yes. Age and fitness do not predict who will be affected. Fit trekkers sometimes climb too fast. Pace yourself, report symptoms and follow your guide's advice.
Should I take medication for altitude sickness?
Discuss it with a doctor who knows altitude medicine before you travel. Medication does not replace slow ascent, and we do not recommend doses. General information only, not medical advice.
What should I do if my headache gets worse?
Stop climbing and tell your guide. If it worsens or comes with vomiting, confusion or poor balance, descend and seek medical help. Descent is the main response.
