Altitude sickness

What is it?

Altitude sickness is puzzling. At times it occurs when you travel too high too quickly, but not at others. It’s unpredictable, happening on one climb but not the next. But it should always be taken seriously. What are the symptoms?

They often include headache, nausea and vomiting, dizziness, tiredness, loss of appetite and shortness of breath. They usually develop between six and 24 hours after reaching altitudes of more than 3,000m (9,842ft) above sea level and are usually worse at night.

It’s not possible to get altitude sickness in the UK because the highest mountain, Ben Nevis in Scotland, is only 1,345m.

How to prevent it

The best way is to travel up to altitudes beyond 3,000m slowly. Also take the precaution of travelling with these medicines for altitude sickness when you climb: ■ acetazolamide, a diuretic, to prevent and treat high altitude sickness

■ ibuprofen and paracetamol for headaches

■ anti-sickness medication, like promethazine, for nausea.

Before any expedition, research the symptoms and treatments. What’s the treatment?

If you think you have altitude sickness, stop and rest where you are. Don’t go any higher for at least 24-48 hours; if you have a headache, take painkillers; if you feel sick, take anti-sickness medication and make sure you’re drinking enough water.

You can continue going up with care once you feel fully recovered. If you don’t feel any better after 24 hours, you should go down by at least 500m (about 1,600 feet). If your symptoms don’t improve or get worse, descend and see a doctor as soon as possible.

If the symptoms of altitude sickness are ignored, they can lead to life-threatening conditions affecting the brain or lungs. Highaltitude cerebral edema (HACE) is the swelling of the brain caused by a lack of oxygen and high-altitude pulmonary edema (HAPE) is a build-up of fluid in the lungs.

Both conditions are serious and require immediate treatment.