Version July 2025
AMS: acute mountain sickness; HACE: high-altitude cerebral edema; HAPE: high-altitude pulmonary edema; ICP: intracranial pressure; IM: intramuscular; IV: intravenous; L: liter; Sp02: oxygen saturation.
* A descent of approximately 1000 m (3300 ft) is usually lifesaving.
¶ Dexamethasone does not facilitate acclimatization (unlike acetazolamide) and may give a false sense of security when symptoms diminish. Symptoms can recur once dexamethasone is stopped if descent/acclimatization have not been accomplished.
Δ Acetazolamide aids with acclimatization. We administer 125 to 250 mg orally twice daily and continue until symptoms resolve (usually one to three days while the patient remains at the same altitude). Refer to drug monograph for dose adjustments for kidney impairment.
◊ Oxygen 1-3 L per minute via nasal canula for a short duration (eg, one hour) may be sufficient to allow individuals to remain at altitude and slowly acclimatize without the need for descent.
§ Descent to an altitude lower than that where symptoms started is an effective and rapid treatment for AMS, but it is not mandatory except if symptoms are intractable or suspicion that illness is progressing to HACE or HAPE.
¥ One hour of hyperbaric therapy in a portable chamber can relieve symptoms. Hyperbaric therapy is unnecessary for the treatment of AMS in the hospital and at lower elevations where supplemental oxygen alone is sufficient to alleviate symptoms.
