Acute mountain sickness (AMS) is a condition that can occur when individuals ascend to high altitudes too quickly. It is caused by reduced oxygen levels in the atmosphere, leading to symptoms such as headache, nausea, dizziness, and fatigue. AMS typically affects people at elevations above 2,500 meters (about 8,200 feet). To prevent AMS, it is important to acclimatize gradually by ascending slowly and allowing the body time to adjust. Staying hydrated and avoiding alcohol can also help. In severe cases, AMS can progress to more serious conditions like high altitude pulmonary edema (HAPE) or high altitude cerebral edema (HACE), which require immediate medical attention.