Introduction
Altitude sickness, also known as acute mountain sickness (AMS), occurs when a person ascends to high altitudes too quickly, typically above 2,500 meters (8,200 feet). At higher elevations, the air contains less oxygen, which can make it difficult for the body to adjust. Altitude sickness can affect anyone, regardless of age or physical fitness, and can range from mild discomfort to life-threatening conditions if not managed properly.
Causes
Altitude sickness is caused by reduced air pressure and lower oxygen levels at high elevations. When the body does not have enough time to acclimatize, it struggles to deliver sufficient oxygen to tissues and organs. Rapid ascent, physical exertion, and a history of altitude sickness increase the risk. There are three main forms of altitude sickness: acute mountain sickness (mild), high-altitude cerebral edema (HACE), and high-altitude pulmonary edema (HAPE), with the latter two being severe and potentially fatal.
Symptoms
Symptoms of altitude sickness usually develop within hours of reaching a higher elevation. Common symptoms include:
- Headache
- Nausea and vomiting
- Dizziness or lightheadedness
- Fatigue and weakness
- Loss of appetite
- Difficulty sleeping
- Shortness of breath with exertion
Severe forms (HACE and HAPE) may present with:
- Confusion or difficulty walking (HACE)
- Severe shortness of breath, even at rest (HAPE)
- Cough, sometimes with frothy or bloody sputum (HAPE)
- Blue or gray lips and fingernails
- Chest tightness
Diagnosis
Diagnosis is based on recent travel to high altitude and the presence of characteristic symptoms. A healthcare provider will assess symptoms and may perform a physical examination. In severe cases, oxygen saturation levels may be measured, and imaging studies (such as a chest X-ray) may be used to check for pulmonary edema.
Treatment Options
The primary treatment for altitude sickness is to stop ascending and, if symptoms are severe, to descend to a lower altitude as soon as possible. Other treatment options include:
- Rest and avoiding further ascent until symptoms resolve
- Supplemental oxygen, if available
- Medications such as acetazolamide to speed acclimatization and relieve symptoms
- Dexamethasone for severe symptoms or cerebral edema
- Pain relievers for headache and anti-nausea medications as needed
Severe cases (HACE or HAPE) require immediate descent and emergency medical care.
Prevention
Preventing altitude sickness involves gradual ascent, allowing the body time to acclimatize. Recommendations include:
- Ascend slowly, especially above 2,500 meters (8,200 feet)
- Spend a few days at intermediate altitudes before going higher
- Avoid strenuous activity for the first 24–48 hours at high altitude
- Stay well-hydrated and avoid alcohol
- Consider preventive medications (such as acetazolamide) if you have a history of altitude sickness or are planning rapid ascent
When to Seek Medical Care
Seek medical attention immediately if you or someone you are with experiences:
- Severe shortness of breath at rest
- Confusion, difficulty walking, or loss of coordination
- Coughing up blood or frothy sputum
- Blue or gray lips or fingernails
- Worsening symptoms despite rest
Takeaway
Altitude sickness is a potentially serious condition that can affect anyone traveling to high elevations. Gradual ascent, proper acclimatization, and awareness of symptoms are key to prevention and safety. If symptoms become severe, immediate descent and medical care are essential.