Altitude sickness can develop when a person climbs a high mountain or travels to a place 2,000 meters (6,500 feet) or higher above sea level.

Altitude sickness or acute mountain sickness (AMS) includes a broad range of illnesses and their associated symptoms. Altitude sickness can affect anyone who ascends to an altitude of 2,000 meters (6,500 feet) or more.

Altitude sickness can be anything from a mild headache to brain swelling and even death. It is something every person going to a high-altitude area should know about before they ascend.

What is altitude sickness?


Altitude sickness is the attributing cause of any symptom, such as headache, nausea, confusion, coma, and even death, that is brought on by ascending into high altitude areas. It is a temporary illness alleviated when the affected individual descends back to lower altitudes.

In terms of altitude sickness, what is “high elevation”?

Climbing to these altitudes can cause altitude sickness symptoms such as:

  • High Altitude: 8,000 to 12,000 feet above sea level is considered a “high altitude.”
  • Very High Altitude: 12,000 to 18,000 feet in altitude.
  • Extremely high altitude: 18,000 feet or more.

To put it into perspective, New York City is 33 feet above sea level. Denver (known as the “Mile High City”) stands at 5,000 feet, while several Rocky Mountain ski resorts are at 11,000 feet or more. The Grand Canyon has an elevation of 6,600 feet above sea level. Mount Everest has a summit elevation of over 29,000 feet.

What causes altitude sickness?

The causes of altitude sickness are still not fully understood. At altitudes of 2,000 meters or more, oxygen concentration remains the same but doesn’t enter your body the same way it does at sea level; oxygen cannot get into your body in adequate amounts.

One reason for this is decreased air pressure, and this is the main cause that lies behind the development of altitude sickness.

The symptoms of altitude sickness

Symptoms of altitude sickness can range from mild headaches or nausea to more severe symptoms like brain swelling, confusion, fluid in the lungs, severe difficulty breathing, and even death.

About 20% of people will develop a mild form of altitude sickness after ascending to heights of 2,000 meters or more, and after 4,200 meters (13,800 feet), the majority of people will experience some degree of altitude sickness.

The majority of persons who suffer from altitude sickness get AMS or acute mountain sickness. Moreover, at 10,000 feet above sea level, 75% of persons will experience minor symptoms. AMS is classified into three types:

  • Mild AMS: Symptoms such as a mild headache and tiredness do not impede daily activities. After a few days, your symptoms will improve as your body adjusts. As your body adjusts, you should be able to stay at your present height.
  • Moderate AMS: Symptoms begin to obstruct your activities. You may feel severe headaches, nausea, and difficulties coordinating your movements. To feel better, you’ll need to descend.
  • Severe AMS: Even at rest, you may feel short of breath. Walking can be challenging. You must immediately descend to a lower altitude and seek medical attention.

Altitude sickness complications

Severe types of altitude sickness can develop at exceedingly high altitudes. The two most severe types of altitude sickness are pulmonary edema (fluid in the lungs) and cerebral edema (fluid in the brain) (swelling of the brain).

High altitude pulmonary edema is known as “High Altitude Pulmonary Edema” (HAPE), while cerebral edema is known as “High Altitude Cerebral Edema” (HACE).

HAPE and HACE are potentially fatal conditions, and a steroid called dexamethasone can be administered to relieve symptoms until the affected person can descend to a lower altitude. Many of the lesser altitude sickness symptoms may be handled without descending.

This decline may generally be avoided with rest, medication to treat symptoms, and enough fluids to prevent dehydration.

High altitude cerebral edema (HACE)

High altitude cerebral edema (HACE) is swelling of the brain induced by a lack of oxygen.

HACE symptoms include: 

  • weakness
  • Being unwell and feeling sick
  • Coordination problems
  • feeling confused
  • Experienced hallucinations

A person suffering from HACE may be unaware that they are unwell. They may argue that they are OK and wish to be left undisturbed. HACE can manifest itself in a matter of hours. If not treated quickly, it can be deadly.

HACE Treatment

  • quickly descends to a lower altitude.
  • Dexamethasone should be taken
  • If available, provide bottled oxygen.

Dexamethasone is a steroid medication that lowers brain swelling. Professional mountain climbers frequently carry it as part of their medical equipment. If you can’t get down right away, dexamethasone can help ease discomfort until you can.

You should seek medical attention as soon as possible for further treatment.

High altitude pulmonary edema (HAPE)

A buildup of fluid in the lungs is known as high altitude pulmonary edema (HAPE).

HAPE symptoms include:

  • Cyanosis: a blue tinge to the skin or lips (cyanosis)
  • breathing difficulties even while resting.
  • Chest constriction
  • A prolonged cough that produces pink or white foamy fluids (sputum).
  • Fatigue and weak.

HAPE symptoms might occur a few days after arriving at a high altitude. If not treated quickly, it can be deadly.

HAPE Treatment:

  • Quickly descends to a lower altitude.
  • Use nifedipine.
  • If available, provide bottled oxygen.

Nifedipine is a medication that helps to relieve chest stiffness and improve breathing. It is also frequently included in the medical supplies of an expedition.

You should seek medical attention as soon as possible for further treatment.

Who is at risk of getting altitude sickness?

It is a common misconception that if a person is active and healthy, they are unlikely to suffer from altitude sickness. Altitude sickness may strike anyone at any moment if they are at or above 2,000 meters (6,500 feet). Altitude sickness may affect hikers, skiers, mountain climbers, travelers, and tourists alike.

Fit young men are at a higher risk of altitude sickness than others. This may appear unusual, but there is a very good explanation behind it. If a person rapidly ascends, altitude sickness is more likely to occur.

People who are overconfident in their fitness and abilities tend to assume they are unlikely to acquire altitude sickness and so ascend more quickly, increasing their chances of experiencing altitude sickness.

Altitude sickness may affect everyone. Your age, gender, or overall health do not appear to influence your risk. You may be more vulnerable if you:

  • If you have a lung or heart issue, your doctor may advise you to avoid high altitudes if at all feasible.
  • Consult with your physician prior to actually heading to a high-altitude region if you are pregnant.
  • Living at a low elevation: Because your body isn’t accustomed to higher elevations, you’re more susceptible to symptoms. If you’re going to a high-altitude area, you should be aware of the signs of altitude sickness and how to manage it.

If you’ve already had altitude sickness, talk to your doctor about preventative and treatment options before your next trip.


It’s most likely altitude sickness if you experience a headache and at least one additional symptom within 24 to 48 hours after relocating to a higher elevation. If you’re ascending, a more experienced climber may detect indications of altitude sickness and point you in the right direction for assistance.

A healthcare specialist will inquire about your symptoms, activities, and location if you have serious altitude sickness. The provider may do a physical exam, which may include listening to your chest.

A chest X-ray may be required to determine whether or not there is fluid in your chest. In extreme circumstances, your doctor may request a brain MRI or CT scan to look for fluid in the brain.

Preventing altitude sickness

mountain hiking

The faster a person ascends and the harder the person pushes themselves, the higher the chances of developing altitude sickness. This also increases the chances of developing a more severe form of altitude sickness.

New research is revealing the usefulness of Viagra in the treatment of altitude sickness, but no conclusions have been made. Following the advice listed below is the best way to avoid altitude sickness.

  • The only way to avoid altitude sickness is to ascend gradually. After ascending 3,000 meters (9,840 feet) or more, the basic rule of thumb is to not rise more than 300 meters (980 feet) every day.
  • Avoid strenuous activity during the first 24 hours. Skiing, climbing, or trekking during the first 24 hours reduces the likelihood of acquiring altitude sickness.
  • While at high elevations, do not consume alcohol or use smoke. Tobacco inhibits oxygen exchange, increasing shortness of breath and respiratory problems. Alcohol can induce severe dehydration. Altitude sickness can be exacerbated by alcohol and cigarette use.
  • Maintain appropriate hydration. Altitude sickness at high elevations is accelerated by dehydration at high elevations. Begin drinking plenty of water before ascending to high altitudes. If you land in a high-altitude place while dehydrated, you have an increased probability of acquiring altitude sickness or worsening altitude sickness.
  • If you must fly or drive somewhere and are unable to spend time in lowland areas along the route, the medicine acetazolamide can help accelerate acclimatization.
  • If you walk, trek, or climb more than 10,000 feet, go only up 1,000 feet every day. Rest at that height for at least a day for every 3,000 feet climbed.
  • Ascend high and sleep low: If you have to climb more than 1,000 feet in a day, be sure you return to a lower altitude to rest.

Treating high altitude sickness

mountain hiking

There is really only one way to treat altitude sickness, and that is decent. Most mild cases of altitude sickness can be treated without descent, but if symptoms do not subside or worsen, the descent is required.

Severe altitude sickness, such as HAPE or HACE, are life-threatening situations that require medical attention and descent ASAP.

Trekking in high-altitude areas, such as Tibet in the Himalayas or South America, can be very adventurous, but medical emergencies in foreign countries can be extremely costly and turn an adventure into a disaster.

Seek medical advice before you leave, and if you develop altitude sickness and you are not sure what to do, contact a medical professional before severe altitude sickness develops.

Things to keep in mind

  • Mountain climbers are susceptible to altitude sickness.

Altitude sickness is induced by fast climbing, which does not give the body enough time to acclimate to decreased oxygen and changes in air pressure.

  • Headache, vomiting, sleeplessness, and decreased performance and coordination are among the symptoms.
  • Fluid can accumulate within the lungs, brain, or both in extreme instances, which can be deadly.
  • Descending promptly, drugs, and the use of oxygen delivered from a handheld container are all alternatives for first aid.

Frequently asked questions

What are the remedies for severe altitude sickness?

Treatments are determined by your symptoms:

  • Dexamethasone, a steroid that helps lower swelling in the brain, may be required for fluid in the brain (HACE). Dexamethasone is occasionally used as preventative medicine.
  • Fluid in the lungs (HAPE) may necessitate the use of oxygen, medicine, a lung inhaler, or, in extreme cases, a respirator.
  • If you require more oxygen, your doctor may give you acetazolamide, which raises your breathing rate and allows you to take in more oxygen. The medication allows your body to acclimate to higher elevations more quickly and decreases symptoms of altitude sickness.

Is altitude sickness harmful in the long run?

Altitude sickness has no long-term detrimental consequences if you take precautions and relocate to a lower height when you get symptoms. You’ll be OK in just a few days. You can continue to go to higher elevations after you feel better, as long as you do so gently and safely.

Is it possible for altitude sickness to be fatal?

Altitude sickness can be deadly in rare situations. If you have HAPE or HACE, you may have problems such as coma or even death. To lower your risk, seek therapy as soon as possible.

Is it possible to recover from altitude sickness?

Altitude sickness is only short-lived. You’ll feel better after you return to a lower altitude. When you resume your ascent (or on your next climb), travel slowly to allow your body to adapt.