Altitude Sickness, also termed as High Mountain Sickness is a type of condition that is defined by a feeling of discomfort or uneasiness due to rapid exposure of a low amount of oxygen at high elevation. Also known in some parts of the world as Hypobaropathy or Acosta disease, high altitude sickness typically happens above 2500 metres or 8000ft.

Altitude sickness

At sea level, the concentration of atmospheric oxygen is 21% with the surrounding air pressure at 760 mm of Hg. As one travels higher up, the surrounding air pressure known as the barometric pressure decreases along with a fall in the oxygen levels. If you stay at a higher altitude, slowly with time your body adjusts to the change in pressure, i.e. it acclimatizes. But if you are just travelling in a plane, or hiking, skiing or driving, your body may not have enough time to adjust to the surrounding pressure resulting in acute mountain sickness.

Rising to extreme higher altitudes without acclimatization results a sudden fall in blood pressure causing fluid to leak from tiny blood vessels. This condition ultimately leads to potentially dangerous fluid build-up in the lungs and the brain resulting in serious risk of life-threatening conditions.

Altitude sickness is of three types, mainly:

Acute Mountain Sickness (AMS):

It is the most common and mildest form of altitude sickness. The symptoms can feel like a hangover resulting in headaches, muscle aches, dizziness, and nausea.

High Altitude Pulmonary Edema (HAPE):

This is a chronic form of altitude sickness that characterizes a build-up of fluid in the lungs that can be very dangerous and even life-threatening. Also Read: Pulmonary Edema: Causes, Symptoms And Treatment

High Altitude Cerebral Edema (HACE):

The most severe form of altitude sickness happens when there is an accumulation of fluid in the brain. It is life-threatening and requires immediate medical help.

People travelling to extreme heights or having an existing heart or lung condition or having acute mountain sickness or diabetes or anaemia are at a higher risk of getting altitude sickness.


The common signs and symptoms usually crop up within 12 to 24 hours of reaching a higher elevation and mostly includes:

Acute Form:

  • Nausea
  • Vomiting
  • Trouble sleeping
  • Headache
  • Fatigue
  • Swelling up of limbs
  • Loss of appetite

Chronic Form:

  • Shortness of breath at rest
  • Racing heartbeat
  • Altered vision
  • Hallucinations
  • Insomnia
  • Exhaustion or extreme weakness
  • Dry cough with pink foamy mucous
  • Severe headache
  • Disorientation and inability to walk
  • Seizures
  • Coma

Diagnosis And Treatment

The usual diagnosis depends upon experiencing any of the aforementioned acute signs and symptoms having climbed an approximate height of 2500 ft. The doctor usually performs a thorough physical check-up to see if there are any respiratory problems, like headaches or pain in the body. The doctor may also perform an X-ray of the chest or CT-Scan of the head to check for any fluid build-up.

Although acute altitude sickness can be treated by just moving to a lower level and allowing the body to get acclimatized, a severe or chronic condition requires immediate medical assistance including oxygen treatment, prescribing or injecting pain or anti-nauseatic medications followed by moving the patient to a much lower altitude. Also Read: Oxygen Therapy Prevents Respiratory Failure

Depending upon the type of altitude sickness, the doctor may suggest some self-care tips and prescribe some medications which include:

  • Moving down to a lower altitude
  • Drinking plenty of fluids
  • Avoiding smoking and intake of alcohol
  • Adequate resting
  • Getting pure oxygen
  • Using inhalers
  • Taking prescribed pain killers and blood pressure-lowering medications

 But the best way to avoid high altitude sickness is to allow your body to get acclimatized or used to the surrounding air and pressure. This is generally done by taking adequate breaks of a complete day while one is hiking or driving to a higher altitude.