Why does altitude sickness cause nausea?

Higher elevations have lower air pressure, so less oxygen is transferred into the blood with each breath. The brain and digestive system can both be affected while the body adapts. Nausea may occur alongside headache, tiredness, light-headedness, poor appetite, or disturbed sleep. Nausea is a very common presentation of Altitude Sickness. Feeling sick can also result from a stomach infection, motion sickness, alcohol, anxiety, medicines, or food-related illness, so the timing and accompanying symptoms matter.

Pause at the current elevation and do not climb higher while you feel unwell. Rest, sip fluids, and choose small, simple meals if tolerated. Avoid alcohol and heavy exertion. An anti-sickness medicine may be suitable for some people, but check with a clinician or pharmacist, especially if you take regular medicines. If nausea continues or worsens, descend to a lower elevation rather than trying to push through it. Read about Nausea for other causes and self-care considerations.

Descend and arrange urgent medical assessment for repeated vomiting, inability to keep fluids down, severe or worsening headache, confusion, marked unsteadiness, unusual sleepiness, breathlessness at rest, or a new cough. Do not leave someone alone if their thinking or coordination is changing. Dehydration can develop when vomiting or poor intake continues, so seek advice early when drinking is difficult.

Before a high-altitude trip, ask how to build rest days into your route, whether a previous episode changes your plan, and whether you can use any nausea or prevention medicine safely. Mention pregnancy, heart or lung conditions, and all medicines or supplements you take.