Altitude sickness, also called Acute Mountain Sickness (AMS), can be deadly. A bit of knowledge and preparation prior to hiking (or walking around) at altitude can mean the difference between a safe and pleasurable trip or a headache-filled experience that could potentially end with medical evacuation off a mountain.
What is altitude?
Altitude is generally divided into the following levels:
High altitude ranges from 4,950 – 11,500ft (1,500 – 3,000m). A traveler headed to this level will typically experience decreased exercise performance and increased breathing rates. Altitude sickness is more common above 8,200ft (2,500m)
Very high-altitude ranges from 11,500 – 18,050ft (3,500 to 5,500m). Severe altitude sickness is more common at this altitude, as well as hypoxia
Extreme altitude is above 18,050ft (5,500m). Acclimatization to this altitude is impossible, and rapid ascent to this altitude is very dangerous.
Travelers headed to high altitude should be aware of a few medical terms and conditions that they might encounter themselves or in their traveling companions.
Stages of altitude sickness
Acute Mountain Sickness/AMS
This is the broad term for altitude sickness. Symptoms of AMS include a headache (often throbbing, worse when bending over), nausea/vomiting, fatigue, and a general feeling of a hangover.
High Altitude Cerebral Edema (HACE)
Is a life-threatening emergency that has symptoms of ataxia (walking in a stumbling manner) and changes in mental status such as confusion or lethargy? This is literally swelling of the brain.
Symptoms of AMS are also usually present.
High Altitude Pulmonary Edema (HAPE)
Is a life-threatening emergency with symptoms of cough (wet or dry), difficulty breathing with mild exertion, and all the symptoms of AMS. Fluid collects in the patient’s lungs.
The definitive treatment for all altitude sickness is descent.
Treatment of high-altitude sickness of all kinds centers around the prompt recognition of the symptoms and realizing that altitude could be the cause of the illness. First and foremost, upon beginning to feel ill at altitude, do not ascend any higher.
Alcohol or sedatives, which can mask the symptoms of AMS, should be avoided for the first few days of altitude. Staying hydrated is also important.
Altitude sickness medications
Certain medications can help prevent and even treat AMS. The most commonly used medication is acetazolamide. This medication is used to both prevent and treat symptoms of AMS. Often taken as a 125mg tablet, twice per day, acetazolamide is effective at preventing AMS symptoms. This medication has the potential to cause allergic reactions in people with a history of sulfa allergies and can change the way some foods or drinks taste especially carbonated beverages. Overall, the medication is very well tolerated and is a viable option for travelers looking to take precautions in preventing AMS. This medicine should be started 24 hours before making an ascent, while at altitude and for 48 hours after a descent.
Dexamethasone is a steroid that can be used as a prophylactic medicine for those unable to tolerate acetazolamide. This medicine is best used as treatment but is still an option.