Dexamethasone (Decadron®) is a potent steroid used to treat brain edema. Whereas acetazolamide treats the problem (by accelerating acclimatization), dexamethasone treats the symptoms (the distress caused by hypoxia). Dexamethasone can completely remove the symptoms of AMS in a few hours, but it does not help you acclimatize. If you use dexamethasone to treat AMS you should not go higher until the next day, to be sure the medication has worn off and is not hiding a lack of acclimatization.
Side effects include euphoria in some people, trouble sleeping, and an increased blood sugar level in diabetics.
For treatment of AMS: Two doses of 4 mg, 6 hours apart. This can be given orally, or by an injection if the patient is vomiting. Children may be given 1 mg/kg of body weight, up to 4 mg maximum; a second dose is given in 6 hours. Do not ascend until at least 12 hours after the last dose, and then only if there are no symptoms of AMS.
AMS symptoms resolve very rapidly (minutes) on moderate-flow oxygen (2-4 liters per minute, by nasal cannula). There may be rebound symptoms if the duration of therapy is inadequate - several hours of treatment may be needed. In most high altitude enviroments, oxygen is a precious commodity, and as such is usually reserved for more serious cases of HACE and HAPE.
Treatment in a portable hyperbaric bag (see physician's section for details) is essentially equivalent to descent or treatment with oxygen; the person is inside a pressurized bag breathing an atmosphere equivalent to a much lower altitude. AMS symptoms rapidly resolve (minutes), but may recurr if treatment is too short - at least two hours are needed. Dexamethasone works as well, though not quite as fast, is much cheaper, and far less labor-intensive than hyperbaric therapy. Hyperbaric treatment is usually reserved for more serious cases such as HACE and HAPE.