What should you know about dealing with altitude sickness?

Dealing with altitude sickness means stopping ascent, resting, monitoring symptoms, and descending promptly if they worsen. It can happen when the body has not adjusted to lower oxygen at high altitude. Headache, nausea, dizziness, tiredness, and poor sleep may begin after arrival or further ascent. Mild symptoms should not be ignored because serious altitude illness can develop.

Rapid ascent gives the body less time to adjust breathing, heart rate, and fluid balance. Mild acute mountain sickness commonly causes a [Headache](/symptoms/headache/) with one or more symptoms such as [Nausea](/symptoms/nausea/), reduced appetite, dizziness, or fatigue. Symptoms often improve when a person rests at the same elevation, but worsening symptoms indicate that descent is needed.

Stop going higher while symptoms are present. Rest, avoid alcohol and sedatives, drink normally, and use only medicines that a clinician or pharmacist has advised for you. Travel with another person who can observe changes. If symptoms do not improve, descend to a lower altitude; do not rely on sleep or pain relief to mask deterioration. Plan gradual ascent and rest days when arranging future trips.

Descend urgently and seek emergency help for breathlessness at rest, confusion, inability to walk normally, fainting, severe weakness, blue lips, or a cough producing frothy or bloody mucus. Do not leave a severely unwell person alone. A [Travel Health Consultation](/treatments/occupational-and-travel-medicine/travel-health-consultation/) can review destination, ascent plan, medicines, and previous altitude reactions before travel.

Is my destination and ascent route suitable for my health? Should I carry preventive or emergency medicine? How can heart, lung, pregnancy, or sleep conditions affect my risk? What exact symptoms mean I must descend or seek emergency care?