Feeling fine at sea level doesn't protect you. Altitude sickness can hit anyone above about 2,500 meters (8,200 ft). Symptoms can start within hours. Knowing what to watch for saves you stress and can save lives.
What it is: Altitude sickness happens when your body can't get enough oxygen at higher elevations. The common form is acute mountain sickness (AMS). More serious types are high altitude cerebral edema (HACE) and high altitude pulmonary edema (HAPE). AMS feels like a bad hangover. Headache, nausea, dizziness, and poor sleep are typical. If you notice confusion, trouble walking, or severe shortness of breath, treat it as an emergency.
Go up slowly. Increase sleeping altitude by no more than 300–500 meters (1,000–1,600 ft) per day once above 3,000 meters. Rest a day every 600–900 meters. Stay hydrated and eat carbs. Avoid heavy alcohol and sedatives, especially the first nights. Consider "climb high, sleep low"—hike higher in the day but sleep lower.
Use a pulse oximeter if you want numbers, but don't depend on it alone. Your symptoms matter more than a single oxygen reading. Train smart: build aerobic fitness, but know fitness doesn't guarantee protection.
Acetazolamide (Diamox) helps you acclimatize faster. A common preventive dose is 125 mg twice daily, starting a day before ascent and continuing for 48 hours after reaching the goal altitude. Side effects include tingling hands or a funny taste. Dexamethasone can reduce brain swelling and is used for HACE or severe AMS when descent isn't immediate. Nifedipine helps with HAPE in some cases. Always get medical advice before using these drugs.
If symptoms are mild, stop climbing and wait. If symptoms improve, you can go on slowly. If symptoms worsen, descend at least 500–1,000 meters immediately. Give oxygen if available. Evacuate to a lower altitude for severe cases. Don't try to tough it out. HACE and HAPE are life-threatening.
Practical travel tips: Choose itineraries that allow gradual ascent. Ask guides about emergency plans and evacuation options. Pack a basic altitude kit: acetazolamide if prescribed, a small oxygen cylinder or concentrator if possible, and a pulse oximeter. Know the nearest clinic or heli-evac route.
Special groups: Children and older adults can get sick too. Pregnant people should avoid high altitudes above 2,500 meters unless cleared by their doctor. People with heart or lung disease need a medical check before high-altitude travel.
Final note: Most altitude sickness is preventable with slow ascent and sensible habits. If you recognize the signs early and act quickly—stop, rest, use meds if advised, and descend—you cut the risk of an emergency. Enjoy the views, but respect the mountain.
Quick checklist: ascend slowly, hydrate, avoid alcohol, carry acetazolamide if prescribed, know emergency descent plan, carry pulse oximeter, get medical clearance if heart/lung disease. If severe symptoms appear—confusion, inability to walk, or extreme breathlessness—descend now and seek urgent care.
Travel insurance that covers helicopter evacuation is worth checking. Plan ahead.
