Acetazolamide (Diamox) may be used to help prevent Acute Mountain Sickness (AMS) when taken before ascent and can speed recovery if taken after symptoms have developed. An effective dose that minimizes symptoms should be started 24 hours before ascent and continuing the first 2 days at altitude, or longer if ascent continues.
- Recommended for people with prior history of AMS and ascending to 8,200–9,100 ft (2,500–2,800 m) or higher in 1 day.
- No history of AMS and ascending to more than 9,100 ft (2,800 m) in 1 day
- All people ascending more than 1,600 ft (500 m) per day (increase in sleeping elevation) at altitudes above 9,900 ft (3,000 m)
- Very rapid ascents (such as less than 7-day ascents of Mount Kilimanjaro)
It is best avoided by people with history of anaphylaxis to any sulfa. People with history of severe penicillin allergy have occasionally had allergic reactions to acetazolamide. Contraindicated for children younger than 12 years of age.
Dexamethasone (Decadron) is usually reserved for treatment. The adult dose is 4 mg every 6 hours. An increasing trend is to use dexamethasone for “summit day” on high peaks such as Kilimanjaro and Aconcagua, in order to prevent abrupt altitude illness.