Ilia Jbankov
FNP-BC Medcor Provider

Are you a fan of skiing, snowboarding, or mountain climbing? Have you ever dreamed of visiting a mountainous destination such as Lhasa in Tibet, Cusco in Peru, or La Paz in Bolivia? Have you thought of making a trip to one of Colorado’s mountain resort towns like Aspen, Breckenridge, or Vail?

If so, you are guaranteed to enjoy some amazing views.

But before you start packing, there is one thing you should know about destinations at higher elevations: altitude sickness. In order to enjoy those spectacular views, be prepared and know what to do in case you develop altitude sickness.

Altitude Sickness

Altitude sickness (also known as mountain sickness) is a medical condition that results from hypoxia (low oxygen levels) in the body. Hypoxia can occur at higher altitudes because oxygen pressure (amount of oxygen in the air) is lower at higher elevations. For example, at 10,000 ft, the air only has about two-thirds the amount of oxygen compared to sea level.

The body’s natural mechanism to combat changes in altitude (known as acclimatization) is relatively effective, but it generally requires 3–5 days in a higher elevation for your body to make these adjustments. Altitude sickness occurs when change in altitude is quick and the body is not given enough time to adjust. A sudden drop in oxygen level results may cause stress on the body and may lead to a number of symptoms that can be mild to severe, and in some cases, even life-threatening.

The risk for altitude sickness starts at 8,000 ft and increases as the elevation rises. There are three types of altitude sickness:

  • Acute Mountain Sickness (AMS)—mildest form and is very common  
  • High Altitude Pulmonary Edema (HAPE)—dangerous and potentially fatal form
  • High Altitude Cerebral Edema (HACE)—also dangerous and potentially fatal form

Acute Mountain Sickness (AMS)

Acute mountain sickness (AMS) is the mildest form of altitude sickness. Symptoms of AMS may be mild but can be significant in some people. About 25% of travelers to altitudes above 8,000 ft in Colorado experience AMS. Also, approximately 50% of individuals going from sea level to 14,000 ft without enough time for adjustment get AMS.  Symptoms of AMS include:

  • Headache
  • Fatigue
  • Nausea
  • Vomiting
  • Dizziness
  • Muscle aches
  • Loss of appetite

Mild symptoms of AMS usually improve in 1–2 days once your body has had time to acclimate. Over-the-counter medications for headache, muscle aches, nausea, and dizziness may relieve mild symptoms. Some people may notice that their symptoms do not improve with time and/or symptoms may gradually worsen. Moderate symptoms of AMS include:

  • Severe headache not relieved by over-the-counter medication
  • Loss of coordination
  • Difficulty walking
  • Chest tightness

If AMS symptoms worsen or do not improve, you should make your descent to a lower altitude. If symptoms continue worsen or do not improve with descent, you must seek immediate medical care.

High Altitude Pulmonary Edema (HAPE)

High altitude pulmonary edema (HAPE) refers to a dangerous and potentially life-threatening form of altitude sickness. HAPE occurs when fluid enters into the lungs. HAPE may occur 2–5 days after being at a high altitude. HAPE is characterized by the following symptoms:

  • Worsening breathlessness with exertion
  • Progression to breathlessness at rest
  • Rapid breathing
  • Rapid heart rate
  • Weakness
  • Cough
  • Pink froth at the mouth
  • Skin discoloration (blue skin)
  • Elevated body temperature

About 1 in 10,000 skiers in Colorado and 1 in 100 climbers to heights above 14,000 ft develop HAPE. It is a medical emergency and requires immediate medical attention. Of note, HAPE may be preceded or occur in conjunction with symptoms of AMS or may develop by itself. HAPE is associated with the most rapid mortality risk.

Administration of supplemental oxygen or descent to lower altitudes (with minimal exertion when possible) is the mainstay of treatment. Other medical treatment may be given by your healthcare provider.

High Altitude Cerebral Edema (HACE)

High altitude cerebral edema (HACE) is a rare, yet dangerous and potentially fatal form of altitude sickness. HACE is a severe progression of AMS and is usually associated with HAPE. It is caused by a build-up of extra fluid in the brain, leading to swelling of the brain and changes to normal brain function. Symptoms of HACE include:

  • Impaired coordination
  • Staggering gait
  • Confusion
  • Severe or worsening headache
  • Vomiting
  • Altered thinking or behavior
  • Hallucinations
  • Seizures
  • Rapid heart rate
  • Fever

HACE is a life-threatening condition that may lead to coma and death. A diagnosis of HACE requires immediate medical attention.

Preventing Altitude Sickness

Anyone can develop altitude sickness regardless of age, sex, or level of physical fitness. However, it can often be mitigated by taking precautions. Several factors may lead to altitude sickness and controlling these factors may help you safely achieve higher ground.

  • Sleeping Altitude: Sleeping at higher altitudes may lead to a higher level of hypoxia. If you climb more than 1,000 ft in a day, descend to a lower altitude to sleep. If you are at a height of more than 9,000 ft, sleep at an elevation of 1,600 ft or less each day. Never continue ascending and sleeping at higher elevations if you are experiencing even mild symptoms of altitude sickness.
  • Gradual Elevation: Ascending gradually and allowing the body sufficient time for acclimatization before moving onto higher elevation is one of the most important factors. It is recommended to avoid reaching from low elevation to over 9,000 ft sleeping elevation in just one day. If ascending above 9,000 ft, it is first recommended to stay at 8,000 ft to 9,000 ft for a few days in order to achieve acclimatization before proceeding higher. Also, keeping ascent to no more than 1,000 ft a day and resting for at least a day every 3,000 ft is ideal at heights above 10,000 ft. 
  • Acclimatization: Resting periods during ascent provide a great opportunity for proper acclimatization and may prevent most cases of altitude sickness. Additionally, acclimatization increases comfort, improves sleep, provides necessary rest and overall sense of wellbeing.
  • Hydration and Nutrition: Drinking plenty of fluids (about 3–4 quarts a day) and ensuring that approximately 70% of your calories come from carbohydrates helps your body adjust to changes in altitude.
  • Substances to Avoid: Tobacco, alcohol, sleeping pills, narcotic pain relievers, and respiratory depressants should be avoided. However, caffeine can be continued if you regularly consume caffeine. 
  • Risk Factors: Risk factors that increase the likelihood of altitude sickness include: history of prior altitude sickness and higher level of physical activity at high elevation.
  • Medical Conditions: Travelers with certain medical conditions such as heart failure, angina, sickle cell disease, sleep apnea, preexisting hypoxemia, or pulmonary insufficiency should consult with their healthcare provider before traveling to a higher altitude destination.
  • Preventive Medication: If you have a history of significant altitude sickness or if you are traveling to high elevations within a short period of time, your healthcare provider may prescribe a preventive medication. It is best to check with your healthcare provider before traveling.  

Whether you are mountain climbing, participating in winter sports, or taking some well-deserved rest, familiarizing yourself with altitude sickness and ways to prevent and treat it is essential for anyone who expects to travel to higher altitudes. With the right approach, altitude sickness is almost always preventable and easily treatable, and should not cloud anyone’s cheery attitude about altitude. Here’s to reaching new heights!

This article is not intended to diagnose or treat any condition or to give medical advice. Always consult your primary care provider for healthcare instructions. External links are provided as references and do not indicate an endorsement by Medcor. External links are subject to other sites’ terms of use and privacy policies.


American Journal of Neuroradiology, “High Altitude Cerebral Edema,”

Harvard Health Publishing, “Altitude Sickness,” December 2018,

Jon Divine, Justin Mullner, “High-Altitude Cerebral Edema,” American Medical Society for Sports Medicine,

Peter Hackett, David Shlim, “High-Altitude Travel & Altitude Illness,” Centers for Disease Control and Prevention, October 18, 2019,

Swapnil J. Paralikar, “High altitude pulmonary edema-clinical features, pathophysiology, prevention and treatment,” Indian Journal of Occupational and Environmental Medicine 16, no. 2 (2012): 59-62, doi: 10.4103/0019-5278.107066

WebMD, “Altitude Sickness: What to Know,” December 23, 2018,