Quick Answer
Symptoms of altitude sickness can develop within 6 to 24 hours after ascent, with most cases occurring within the first 12 hours. At higher elevations, symptoms can appear even sooner. In extreme cases, high-altitude pulmonary edema (HAPE) or high-altitude cerebral edema (HACE) can develop rapidly, often within 24 to 48 hours.
Understanding Altitude Sickness
Altitude sickness, also known as acute mountain sickness (AMS), occurs when the body cannot adapt quickly enough to high altitudes. This can happen when traveling to elevations above 8,000 feet (2,438 meters). The body needs time to acclimatize to the lower oxygen levels, which is why it’s essential to ascend gradually, allowing the body to adapt.
Prevention and Treatment
Preventing altitude sickness is easier than treating it. To mitigate symptoms, ascend no more than 1,000 to 1,500 feet (300 to 450 meters) per day, and spend at least one night at each intermediate altitude. Diamox (acetazolamide) is a medication that can be taken to help reduce the risk of altitude sickness, but it should only be used under medical supervision. In case of symptoms, immediate descent is usually the best course of action. For mild cases, rest and hydration are key. In severe cases, oxygen therapy may be necessary, and medical evacuation may be required.
Descent and Recovery
If symptoms of altitude sickness persist or worsen, immediate descent is necessary. Descending to a lower altitude can help alleviate symptoms and prevent further complications. The rate of descent depends on the severity of symptoms, but a safe general rule is to descend 1,000 to 2,000 feet (300 to 600 meters) per day. Once symptoms have subsided, it’s essential to allow the body time to recover before ascending again. This may involve a period of rest and observation at a lower altitude before attempting to ascend higher.
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