‘醉氧’ (zuì yǎng) literally means 'intoxicated by oxygen' and refers to a physiological reaction that occurs when people who have spent time at high altitudes return to lower elevations. After adapting to low-oxygen conditions, the body temporarily overreacts to the increased oxygen availability—causing symptoms like drowsiness, fatigue, headache, dizziness, or mild nausea. Though not life-threatening, it’s a real and widely recognized phenomenon among mountaineers, travelers, and residents of high-altitude regions like Tibet or Qinghai.

The term combines 醉 (zuì), meaning 'intoxicated' or 'drunk', and 氧 (yǎng), meaning 'oxygen'. It’s a playful yet scientifically grounded compound, modeled on terms like 醉酒 (zuì jiǔ, 'alcohol intoxication'). Unlike altitude sickness (高原反应, gāoyuán fǎnyìng), which happens when ascending, 醉氧 occurs during descent—and is sometimes called 'reverse altitude sickness' or 'oxygen intoxication' in English medical contexts.