Did You Know – About Altitude Illness?

DID YOU KNOW - Altitude illness can be fatal?


  • Acute mountain sickness (AMS) begins with mild symptoms such as headache and nausea. Altitude illness becomes worse as one ascends higher.
  • If you develop cough and shortness of breath, this can be a sign of fluid in the lungs (high altitude pulmonary edema, HAPE).
  • Vomiting, confusion or unsteady gait can be signs of swelling in the brain (high altitude cerebral edema, HACE). HAPE and HACE can be fatal within 24 hours.

DID YOU KNOW - Altitude illness can start as low as 3,000 meters (10,000 feet)?


  • At 3,000m, the air you breathe contains only 69% as much oxygen as what you would breathe at sea-level. Oxygen levels drop even more as you ascend.
  • How badly you are affected by this oxygen shortage (hypoxia) depends on how high you are, how fast you ascend, and how long you have stayed at that altitude.

DID YOU KNOW - safe travel at high altitudes begins well before the trip?


  • It is your trip - understand your itinerary and the altitude you will be sleeping at each day.
  • A slower ascent is safer and can make for a more comfortable journey.
  • Medications such as acetazolamide (Diamox) can prevent AMS, and speed up acclimatization.

DID YOU KNOW - which are high altitude destinations BEFORE booking your trip?


Some Popular Destinations Altitude (feet) Altitude (meters)
Lhasa, Tibet 12,100 3,650
Cuzco, Peru 11,000 3,300
Everest Base Camp, Nepal 17,700 5,400

DID YOU KNOW - going down to a lower altitude can be life-saving?


  • Be aware of symptoms and danger signs. If the symptoms get worse, listen to your body.
  • Be willing to stop the trip and go down to a lower altitude.
  • Dexamethasone (a strong steroid) is usually reserved for treatment of HAPE/HACE.

ASK YOUR DOCTOR how to prevent and survive altitude illness 

PRECAUTION: Acetazolamide (Diamox) is related to sulfonamide medications. 

Individuals with a history of severe allergy to sulfa (anaphylaxis) should not receive it. 

Written by A/Prof (Adj) Lim Poh Lian – Head, THVC