What are symptoms of altitude sickness?

Altitude sickness can make you feel dizzy and nauseous and may decrease your appetite. The most common manifestation of altitude sickness, Acute Mountain Sickness (AMS), typically doesn't happen below 8,000 feet (2,438.4 m).

You don't have to climb a mountain in order to feel its effects. In the United States, you might experience the effects of AMS in Vail, which sits at a base of 8,120 feet (2,474.98 m). In the Nepalese valleys close to Mount Everest, the lower elevation ranges from around 6,500 to 10,000 feet (1,981.2 to 3,048 m, while it ranges from around 11,000 and 13,000 feet (3,357.8 and 3,962.4 m) in the higher elevation. La Paz, Bolivia, has an elevation of 11,975 feet (3,649.8 m). Travelers to these sites can feel the effects of altitude sickness, even if they don't arrive there by foot.

The symptoms of mild to moderate altitude sickness include headache, decreased appetite or nausea, insomnia, and lightheadedness. With severe altitude sickness, you may have all of the above plus vomiting and shortness of breath. Symptoms of altitude sickness usually start within the first 24 hours of arrival at high altitude, such as a visit to the mountains, and often as early as the first few hours after arrival.

A person suffering from high altitude sickness may be breathing faster, deeper, or both. They will likely have shortness of breath during exertion and a change in the breathing pattern at night. They also awaken frequently at night. Other symptoms include loss of appetite, nausea or vomiting, fatigue or weakness, and dizziness or light-headedness. Those suffering from altitude sickness commonly complain of a headache. Many describe this general feeling as similar to that of a hangover. (This answer provided for NATA by the Marist College Athletic Training Education Program)

Acute mountain sickness (AMS): Common symptoms of acute mountain sickness (AMS) include fatigue, headache, dizziness, insomnia, shortness of breath, nausea, decreased appetite, swelling of the arms and/or legs, and social withdrawal.

High altitude pulmonary edema (HAPE): AMS may progress to high altitude pulmonary edema (HAPE) after more than one day spent at high altitude. Symptoms may develop gradually or suddenly. Common symptoms include shortness of breath (even when resting), gurgling sounds when breathing, wet cough with frothy sputum, and sometimes fever. If left untreated, this condition may lead to respiratory failure in which the lungs are unable to get enough oxygen. As a result, breathing is no longer possible. Without immediate treatment, the patient will die from respiratory failure.

High altitude cerebral edema (HACE): AMS may also progress to high altitude cerebral edema (HACE). The first symptom of HACE is usually confusion. As the condition worsens, the patient may have a difficult time keeping up with others. Then walking and coordination become impaired. As the brain continues to swell, the patient becomes more lethargic. If left untreated, the patient will go into a coma and eventually die.

High altitude retinal hemorrhage (HARH): The most common symptom of high altitude retinal hemorrhage (HARH) is blurred vision. Bleeding in the eye(s) may or may not be visible to the patient. Left untreated, HARH may lead to permanent eye damage or vision loss.

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