Understanding Altitude Sickness
Altitude sickness, or Acute Mountain Sickness (AMS), is your body's response to the lower oxygen levels and reduced air pressure found at high elevations. While the percentage of oxygen in the air remains the same, the 'thin' air means you get less oxygen with
each breath. Most people can ascend to 1,500 to 2,000 meters without issue, but symptoms often start to appear above 2,500 meters (about 8,000 feet). The key issue is ascending too quickly, not allowing your body the crucial time it needs to acclimatize. Physical fitness, while beneficial for the activity itself, does not necessarily prevent you from getting it.
Recognizing the Early Signs
The initial signs of AMS often mimic a hangover, typically developing within 6 to 12 hours after you arrive at a high altitude. A persistent headache is the most common and cardinal symptom. This is often accompanied by one or more other signs, such as dizziness, fatigue, nausea or loss of appetite, and difficulty sleeping. These symptoms frequently appear during the first night at a new elevation as your body struggles to adjust. For most people with mild symptoms, they will resolve within 24 to 48 hours if you rest and do not ascend any higher.
The Golden Rules of Prevention
The best treatment for altitude sickness is prevention, and the most important rule is to ascend slowly. Once you pass 3,000 meters, try not to increase your sleeping elevation by more than 500 meters per day. A common strategy is to 'climb high, sleep low,' meaning you can hike to a higher altitude during the day but return to a lower elevation to sleep. Staying well-hydrated by drinking plenty of water is crucial, while avoiding alcohol for the first 48 hours is highly recommended as it can worsen symptoms. Eating regular, carbohydrate-rich meals can also help maintain your energy levels.
What to Do If Symptoms Appear
If you start to feel the mild symptoms of AMS, the first and most important step is to stop ascending. Rest where you are and allow your body time to acclimate, which can take anywhere from 12 hours to three days. Over-the-counter pain relief can help with the headache. If your symptoms are moderate, don't improve, or get worse, you must descend. Dropping your altitude by just 300 to 1,000 meters can bring significant and rapid relief. Never continue to a higher altitude if you are experiencing symptoms.
When It Becomes an Emergency
While most cases of altitude sickness are mild, it can progress to life-threatening conditions. High-Altitude Cerebral Edema (HACE) is a swelling of the brain, and High-Altitude Pulmonary Edema (HAPE) is a buildup of fluid in the lungs. HACE symptoms include severe headache, confusion, loss of coordination (ataxia), and irrational behavior. A simple test is to see if the person can walk a straight line. HAPE is characterized by extreme shortness of breath even at rest, a persistent cough that may produce frothy or bloody sputum, and chest tightness. HAPE can develop even without the usual AMS symptoms and is the most common cause of death from altitude illness. Both HACE and HAPE are medical emergencies that require immediate descent and medical attention.
