Avoiding altitude sickness in China - a short guide

It's easy for the foreign traveller to forget the vastness of China. By virtue of American movies, books and TV, we're often familiar with the sweeping plains of Montana, the California redwood forests, the mountains of Colorado, the deserts of New Mexico and so on.

China's geographic diversity rivals - and probably exceeds - the continental US (in terms of biodiversity and extremes). Open up Google Maps and turn on the topographic overlay - you'll see that about a quarter of China's map area, the vast majority of its southwest, is connected to the Himalayan plateau. This extends from Sichuan (with Chengdu being the last big Chinese city before the mountains) all the way through to Bhutan, Nepal and northern India, including Mount Everest, K2 and most of the world's 7,000-metre-plus peaks.

All of that is to say that practically, you can drive from Chengdu - elevation 300 metres - to a town at the base of Four Sisters Mountain - elevation 3,100 metres - in less than four hours. Four Sisters is 6,250m, and Mount Gongga, the tallest mountain entirely within China, is around 7,500m and about five hours' drive away from Chengdu.

This means it's easy for unsuspecting people to suddenly be at the mercy of altitude sickness. In Mandarin it's known as 'gaofan', short for 'gaoyuan fanying' (高原反应) or 'plateau reaction'.

There's a range of things you can do to make your life easier at altitude. I'll list them further below roughly in order of how science-backed they are. I will also list some excellent resources that informed this page.

But what does it feel like?

First, altitude sickness affects different people in different ways. It depends on genetics, speed of ascent, acclimatisation period, and other factors such as exertion and water and alcohol consumption.

It can be very unpleasant, but is rarely life-threatening. That said, if you get serious symptoms, the first thing you should do is descend, as that's the only reliable way to reverse symptoms.

It often feels like a pounding headache that won't go away. When you sleep, your breathing and heart rate naturally slow, but with thin air your body can't get enough oxygen - meaning some people wake up in the middle of the night gasping for air - which then leads to interrupted sleep and fatigue.

At altitude, I found my resting heart rate increased to about 110-130bpm, up from 60-70bpm at sea level. Average blood oxygen level also dropped from 98 to 92-95 percent. I constantly felt slightly out of breath.

This is caused by hypoxia, or a lack of oxygen. Chronic hypoxia means your body is consistently not getting the oxygen it needs, which can lead to acute mountain sickness (AMS). The other two acronyms you should be aware of are HAPE (high-altitude pulmonary edema) and HACE (high-altitude cereberal edema). HAPE affects your breathing; HACE your head. HACE is the more severe of the two, and should be treated by descending immediately. If you have a headache, that is normal – but hallucinations, disorientation or confusion is not.

Here are some recommendations, informed by research and experience:

Drink more water than you think you need, and regularly. Aim for approximately 500ml per hour. For hydration, the regularity of the intake is key; if you quaff huge amounts at once it will pass straight through you.
Do not drink alcohol. At the end of a long day, a beer or a small whiskey can be very appealing - but in my experience, even a sip and the pounding headache seems to triple in intensity. Headaches and symptoms tend to be worst during evenings, mornings and nights.
Ascend slowly. Let your body adapt. It can help to spend a night at a midpoint on a mountain, or to 'climb high, sleep low'.
Counter-intuitively, even if you have a headache, many recommend going for a brisk walk (or otherwise getting your heart rate up) in the morning, which apparently helps reoxygenate your blood. Possibly due to the nature of the headache, I found paracetamol and ibuprofen surprisingly ineffective against AMS symptoms.
Avoid over-exerting yourself. Walk more slowly than you usually would (you will find yourself naturally breathing more rapidly at altitude, but don't push it).
Being more physically fit will not necessarily make you less susceptible to altitude sickness. An unfit person will usually move more slowly with a lighter load and is less likely to over-exert.
There is an over-the-counter medication called Diamox which increases oxygen uptake in your blood - some people recommend it (though there is debate in the mountaineering community about the altitude beyond which it's necessary). One side effect is numb/tingling extremities and a slight diuretic effect (needing to pee more). Some say needing to pee several times during the night has the same negative impact on overall sleep quality as altitude sickness itself. It's recommended to start taking this a few days in advance.
There are some less science-backed things that people will tell you to do. I don't know if they work; they probably do not. They include: not overeating, not washing your hair, not showering at all (apparently having a wet scalp makes you more vulnerable – I am skeptical; perhaps if you walked around all day with wet hair outside, but even then...).
Beyond this we get into traditional Chinese and Tibetan medicine. There is not a large body of research about the effectiveness of these, though many local people say they work. I haven't tried them (yet), though probably will for future mountain adventures.

Further resources: