Altitude Sickness

What is altitude sickness?

Altitude sickness (AS) or acute mountain sickness (AMS) is a condition that occurs at high altitudes, when sufficient amount of oxygen is not available from the inhaled air. Generally, altitude sickness is felt when a patient moves quickly from lower altitudes to higher altitudes. A quick hike or drive to high altitudes or mountain peak causes a decrease in oxygen availability (hypoxia). The hypoxia condition increases the amount of blood supply in brain and lungs. Increased blood flow raises the capillary pressure and the fluid seeps out leading to swelling or edema around the brain and lungs among other sites in the body.

What are the types of altitude sickness?

Altitude sickness caused by hypoxia can lead several related syndromes such as :

  • High-altitude cerebral edema (HACE)
  • High-altitude pulmonary edema (HACE)
  • Chronic mountain sickness (Monge‚Äôs disease)

What causes altitude sickness?

The main underlying cause for development of altitude sickness is decrease in oxygen availability.

The symptoms of altitude sickness can be aggravated by :

  • Sleep deprivation,
  • Excessive exertion,
  • Increased loss of body fluid or decreased intake of water,
  • Consumption of alcohol, and
  • Rapid climbing to higher altitudes

What are the symptoms of altitude sickness?

The symptoms of altitude sickness are wrongly diagnosed for common cold, hangover, exhaustion and decrease in body fluids. The common symptoms associated with severe altitude sickness include the following :

  • Throbbing headache (severe during night and when patient wakes up)
  • Difficulty in sleeping and sleep disturbance
  • Fatigue
  • Dizziness
  • Feeling weak and lazy with no energy even to eat or work
  • Loss of appetite
  • Nausea and/or vomiting

Severe altitude sickness will lead to symptoms of related syndromes affecting the lungs and brain in particular. The more definitive symptoms in this regard includes :

  • Confusion and incoordination (not being able to walk straight, ataxia),
  • Lips and fingernails turning blue
  • Changes in breathing rate, rhythm and depth
  • Disorientation
  • Swelling in regions of brain, lungs, peripheral parts and face.

What is the treatment for altitude sickness?

Altitude sickness is diagnosed mainly by clinical evaluation. A medical history indicating recent trips to high altitudes is useful in reaching the diagnosis. Treatment is primarily directed at preventing the symptoms, i.e., moving to lower altitude

To treat mild symptoms of altitude sickness :

  • Spend more time at set high altitudes (allow the body to acclimatize before climbing further).
  • Avoid moving to a higher altitude if altitude sickness symptoms are present, until symptoms reduce (between 12 hours to 3 or 4 days).
  • A slow and gradual ascent will ensure that altitude sickness is prevented.
  • Sufficient rest between periods of activity (walking, hiking, climbing) when in high altitudes.
  • Drinking plenty of water may also help as air is drier at higher altitudes and promotes dehydration.
  • Take certain medication that helps prevent altitude sickness before embarking on a trip.

To treat severe symptoms of altitude sickness :

  • Descend from high altitudes immediately.
  • Oxygen therapy, either through a mask, in oxygen tents or high pressure chambers may be necessary.
  • Take medication immediately.


The major classes of medicines which are commonly used in the treatment and prevention of altitude sickness are:

  • Analgesics and anti-inflammatory drugs to treat headaches , like acetaminophen, ibuprofen and naproxen.
  • Acetazolamides and dexamethasone to prevent altitude sickness
  • Anti-emetics are medication to reduce nausea and vomiting which also helps to prevent worsening of dehydration.

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