What is altitude sickness and what causes it?

Also known as “Mountain Sickness”, altitude sickness is defined as a condition “caused by ascent to a high altitude and the resulting shortage of oxygen, characterized chiefly by hyperventilation, nausea, exhaustion, and cerebral edema”. Supplemental oxygen like Boost Oxygen can help the mild symptoms of altitude sickness, but we want to explain how to recognize the symptoms and what you can do to treat and prevent it.


  • Why does altitude sickness happen? When you go to higher altitudes, there is less oxygen for your body, lungs and blood cells to create energy. The faster you climb to higher altitudes, the more likely you will get it.
  • There are several symptoms of altitude sickness, which can range from mild to more severe symptoms which could require treatment.
  • The ways to treat mild symptoms of altitude sickness include moving to lower altitude levels, rest and pain relievers. Supplemental oxygen can also help mild symptoms.
  • The best ways to prevent altitude sickness are too acclimate your body with altitude changes, stay hydrated and carry supplemental oxygen.

(story continues below photo)




Altitude sickness typically occurs at altitudes over 6,000 feet. The higher you go, the more air pressure drops and there is less oxygen for your body. Simply put, the symptoms of altitude sickness are your body reacting to this lack of oxygen. Altitude sickness also happens if you ascend to higher altitudes too quickly without allowing your body time to acclimate to the altitude changes. It can also occur if you exercise too much (or exert your body) before visiting higher altitudes. Genetics may also increase the risk, including high altitude pulmonary edema (HAPE).



There are two types of altitude sickness: mild and severe. Acute Mountain Sickness (AMS) are the mild symptoms which include headaches, shortness of breath, nausea, dizziness, fatigue and muscle aches. High Altitude Cerebral Edema (HACE) and High Altitude Pulmonary Edema (HAPE) result in more severe symptoms. HACE usually develops after mild forms of AMS and can include trouble walking, worsening headaches and vomiting and confusion. HAPE can result in a buildup of fluid in the lungs that can also be very dangerous. It can also occur WITHOUT the signs or symptoms from AMS or HACE. Symptoms from HAPE can include chest tightness, extreme fatigue, inability to catch your breath even when resting, coughing and fever.



The general rule is to stop ascending to higher altitudes if you experience mild symptoms. You can also treat the mild forms with rest, pain relievers and supplemental oxygen. If you experience the more severe symptoms like HACE or HAPE, it is important to descend to lower levels as soon as possible or seek medical treatment.



The easiest way to prevent altitude sickness is by allowing your body to acclimate to the changes in pressure and altitude by ascending gradually. Going slow allows your lungs to acclimate and your blood cells to carry more oxygen to your organs and tissues. Some basic guidelines are to begin your journey at 5,000-8,000 feet and go no more than 1,000 feet per day. Also, stay hydrated with lots of water and avoid alcohol, tobacco and sleeping pills. If you experience mild symptoms of altitude sickness and follow these guidelines, your symptoms should go away within 24 hours.


To learn even more about Altitude Sickness, please visit this link from Harvard Health Publishing: “Altitude Sickness: What Is It?”


Topics: questions altitude sickness hypoxia recovery altitude health information & research

Share This Article

Written by Bill Banks