The Altitude Safety Checklist

1. See a doctor first: especially if you have heart, lung or blood-pressure conditions, or are pregnant. Ask about preventive medication; do not self-prescribe.

2. Go up gradually: above about 3,000 metres, aim to raise the altitude at which you sleep by only a few hundred metres a day, and plan a rest day every few days.

3. Rest on arrival: a day of light activity before anything strenuous.

4. Drink water: and go easy on alcohol for the first days.

5. Know the symptoms: headache, nausea, dizziness, poor sleep and fatigue are common early signs of altitude sickness.

6. Know the danger signs: severe headache, confusion, loss of balance, breathlessness at rest or a persistent wet cough mean you should descend and seek medical help.

7. Never ascend with symptoms: and never leave a sick person alone.

8. Sleep low, climb high: a day trip to a higher point is safer than sleeping there.

9. Insurance: buy cover that includes altitude, trekking and evacuation.

10. Tell someone: share your itinerary with your host and someone at home.

11. Sun and cold: UV is strong at altitude, and nights are cold; carry sun protection and layers.

12. Listen to your guide: local guides have seen altitude problems many times; follow their advice.