Altitude sickness

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If you are insufficiently accustomed to it, you can get altitude sickness if you stay at high altitudes or if you ascend too quickly. It’s caused by low oxygen content in the air, which can give you problems by causing a lower level of oxygen in your blood. The body needs time to adapt to a lower oxygen content (acclimatisation). The higher the altitude you stay at, or the faster you ascend to this height, the greater will be the likelihood that you’ll suffer from altitude sickness. Generally speaking, its symptoms only become evident above a height of 2,500 metres. Susceptibility to altitude sickness varies from person to person, which means that some people can also experience problems at lower altitudes. Conversely, some people show no symptoms when staying at altitude.

How do you recognise altitude sickness?

Mild symptoms of altitude sickness will usually manifest themselves between several hours to a day after arriving at a high altitude. They usually include a headache and at least one of the following symptoms: nausea and/or vomiting, sleep disorders, dizziness and/or a feeling of weakness. At the beginning the symptoms will be mild, but a headache should set the alarm bells ringing. On average, the complaints will last no longer than a few days and the condition is not serious, providing you do not go any higher while the symptoms prevail. Mild altitude sickness can turn into severe altitude sickness. When this happens the headache and shortness of breath will become worse, even while resting, particularly at night. This can affect you so much that you might even need help to eat and get dressed. In the event of severe altitude sickness you must descend immediately. If it’s not addressed, altitude sickness can lead to fluid in the lungs and brains (pulmonary and cerebral edema), accompanied by coma and even death.

Advice for travellers going to high altitudes

  • Acclimatise for at least two nights at a moderate altitude (1,500-2,500 metres).
  • If you fly directly to a destination that’s 2,500 metres or higher, you should acclimatise at that altitude for a few days before going any higher.
  • You can help your body to adapt by limiting physical exertion and by climbing higher during the day than the altitude at which you sleep at night (climb high, sleep low). Avoid strenuous activity for the first two days that you are above 2,500 metres.
  • As you ascend above 3,000 metres make sure you climb no more than 500 metres per overnight.
  • For every increase in altitude above 500 metres, spend at least two nights at the same height.
  • Drink enough, which means at least a few litres a day (your urine must remain light and clear).
  • Don’t drink alcohol or take sleeping pills.
  • Keep your travel schedule flexible so that you can rest for a few days in the event of altitude sickness.
  • Consult your doctor if you have heart and/or lung complaints.
  • Medication, such as acetazolamide (Diamox®) can be prescribed to accelerate the acclimatisation process. Before taking it always read the enclosed documentation!
    • If you take the medication to prevent altitude sickness, start taking it 24 hours before reaching 3,000 metres. Continue taking them for two days after reaching your maximum altitude.
    • If you take the medication to treat altitude sickness, start taking it if you get a headache and even with milder symptoms if you intend to climb higher. Continue taking them for three days, or less if you descend beforehand. If, after climbing higher, the complaints return, you can start another course of the medication.

Possible side effects of acetazolamide include: tingling in the extremities, change in taste, nausea and having to urinate frequently.

What should you do if you have the symptoms of altitude sickness?

For mild altitude sickness symptoms: do not ascend any further and start taking the acetazolamide. If the symptoms do not improve within a day descend to a lower altitude. If you have a headache you can take paracetamol, and for nausea an antiemetic agent. Once the symptoms subside you can ascend carefully to a higher altitude. For severe altitude sickness: descend immediately to a lower altitude and seek medical help (oxygen and medication). Bear in mind, however, that if you are staying in a remote area access to medical care will be limited! Source: