Altitude sickness, also known as acute mountain sickness (AMS), occurs when individuals ascend to high altitudes too quickly. At elevations above 8,000 feet (2,400 meters), the air pressure decreases, leading to lower oxygen levels. This can cause symptoms such as headache, nausea, dizziness, and fatigue. To prevent altitude sickness, it is essential to acclimatize gradually by ascending slowly and allowing the body time to adjust. Staying hydrated and avoiding alcohol can also help. In severe cases, descending to a lower altitude is necessary, and medical attention may be required for those experiencing more serious symptoms.