Mountain Sickness: Symptoms, Prevention, and Treatment

Mountain sickness (altitude sickness) can ruin a trip fast. It happens when your body can't adjust to lower oxygen at high elevation. Symptoms often start within 6 to 24 hours after ascent and can range from mild headaches to dangerous swelling in lungs or brain.

Recognize the signs early. Headache, nausea, dizziness, trouble sleeping, and loss of appetite are common early symptoms. If you notice shortness of breath at rest, a persistent cough, or severe confusion, treat this as an emergency — these may be signs of high-altitude pulmonary edema (HAPE) or high-altitude cerebral edema (HACE).

Slow ascent is the best prevention. Gain no more than 300–500 meters of sleeping altitude per day above 3,000 meters and rest a day every 1,000 meters. Stay hydrated, eat light meals, and avoid heavy alcohol or sedatives for the first days at altitude.

Acclimatization Tips

Sleep lower than your highest daytime climb when possible — "climb high, sleep low" helps your body adapt. Do short, easy hikes on your first days to test how you feel. Use a pulse oximeter if you want numbers: a healthy acclimatizing oxygen saturation varies with altitude, but sudden drops or very low readings are warning signs.

Medications can help in some cases. Acetazolamide (Diamox) speeds up acclimatization and reduces symptoms; start a day before ascent and continue for a couple of days at altitude. Dexamethasone can treat severe symptoms of HACE. Nifedipine helps with HAPE. Only use medicines according to a doctor's advice and know side effects.

What To Do If Symptoms Appear

If symptoms are mild, stop ascending and rest. Most mild cases improve within 24–48 hours with rest and hydration. If symptoms worsen or new severe signs show up, descend immediately — even a few hundred meters can make a big difference. Oxygen and portable hyperbaric bags are useful when descent is delayed.

Plan ahead: check the route, know evacuation options, and tell someone your schedule. People with heart or lung disease, or those who recently had a respiratory illness, should discuss plans with a doctor before going high. Kids and older people may show different symptoms and need closer monitoring.

Simple gear helps: a basic first-aid kit, a thermometer, a pulse oximeter, and a plan for rapid descent. Practice recognizing symptoms on smaller climbs before attempting very high mountains. Respect how your body feels — pride or impatience can turn a fixable problem into a dangerous one.

High risk starts above about 2,500–3,000 meters, but some people feel sick at lower heights. If you plan fast travel to high towns or quick flights to mountain cities, factor in a day or two to adjust. Also consider travel insurance that covers helicopter evacuation if you go to remote ranges. Know your limits.

Mountain sickness is preventable and treatable when you act early. Know the signs, climb smart, use proven medications when needed, and descend if things get worse. That way you can enjoy the views without risking your health.