Altitude: What It Does to Your Body and How to Prepare

Going up in elevation changes how your body works. Less oxygen means your breathing and sleep change, your heart works harder, and you may feel tired or get headaches. Knowing the signs, using simple prevention steps, and carrying the right medicines can stop mild problems from getting worse.

First, watch for symptoms of acute mountain sickness (AMS): headache, nausea, dizziness, loss of appetite, trouble sleeping and feeling unusually tired. If symptoms are mild, rest and don’t go higher for 24 hours. If symptoms get worse — vomiting, confusion, balance loss or shortness of breath at rest — descend immediately and get medical help.

Simple prevention and self-care

Climb slowly. Gain no more than 300–500 meters (1,000–1,600 feet) of sleeping elevation per day above 2,500 meters (8,200 feet). Hydrate well, avoid alcohol and heavy exertion on the first day at a new altitude, and eat light meals. Sleep higher? Stay put for a day to acclimatize. A small portable pulse oximeter helps track oxygen levels and can warn you if you need to act.

Over-the-counter options help with symptoms: acetaminophen or ibuprofen for headaches, simple anti-nausea meds for vomiting, and oral rehydration if you’re dehydrated. For sleep problems, try short naps and avoid sedating drugs unless advised by a doctor — they can make breathing worse at altitude.

Medications and medical prevention

Acetazolamide (Diamox) is the most used drug to prevent and reduce AMS. Typical prevention dosing is 125 mg twice daily starting a day before ascent and continuing for 48 hours after reaching higher altitude. It speeds up breathing and helps acclimatize, but it can cause tingling, taste changes, and increased urination. People with sulfa allergies should avoid it and ask a clinician for alternatives.

Dexamethasone can relieve severe symptoms fast and is useful for high-risk situations, but it’s a short-term rescue medicine, not a prevention long-term option. If you have heart or lung disease, asthma, diabetes, or pregnancy, talk to your doctor before travelling to high altitude — conditions can worsen and some medicines behave differently with less oxygen.

For frequent travelers, a doctor may suggest portable oxygen, a prescription for nifedipine for high-altitude pulmonary edema (HAPE) prevention in certain situations, or a plan for self-descend and emergency care. Carry a simple altitude kit: pulse oximeter, acetazolamide (if prescribed), basic pain reliever, anti-nausea pills, and clear instructions from your clinician.

If you plan an expedition, check the nearest emergency services and how long rescue or descent will take. Altitude problems are usually preventable with slow ascents and the right supplies. When in doubt, go down — descent works faster than any medicine.

Before travel, get a quick checkup and prescriptions if needed. Give your doctor details: planned altitude, pace of ascent, and medical history. Parents: kids show AMS faster—descend sooner and avoid air travel right after severe symptoms. Buy prescribed meds from licensed pharmacies and carry their original labels. A little planning cuts risk and keeps trips enjoyable. Pack snacks and warm layers.