High altitude pulmonary edema (HAPE) is a life-threatening condition where fluid accumulates in the lungs at altitudes above 8,000 feet, usually developing within 2-3 days. Symptoms include acute mountain sickness, breathlessness, cough with white or pink frothy sputum, a sound resembling crumpled paper when breathing, rapid heart rate, blue lips, and elevated body temperature. HAPE can be mistaken for infections but requires immediate hospitalization at its onset. Prompt oxygen administration can prevent HAPE.