Dexamethasone as Prophylaxis for Acute Mountain Sickness: Effect of Dose Level,

Rapid exposure of unacclimatized individuals to high altitude causes a syndrome termed acute mountain sickness AMS. Prophylactic treatment with high doses of dexamethasone is known to prevent AMS, but carries a high risk of side effects. To determine whether lower doses with less potential for side effects were effective in preventing AMS, 28 men between the ages of 18 and 32 were exposed to a simulated altitude of 4579 m for 45 h in a hypobaric chamber on two occasions while taking one of three doses of dexamethasone 4 mg. 1 mg or .25 mg every twelve hours or a placebo in a double-blind, crossover design. Three independent measures for the presence of AMS showed that the 4 mg dose of dexamethasone reduced the incidence of AMS symptoms compared to placebo and compared to the other dose levels. Dexamethasone did not alter fluid balance or plasma volume changes, but treatment with 1 mg adn 4 mg suppressed cortisol secretion. There was no evidence of adrenal cortical suppression after treatment with dexamethasone or placebo 48 h after discontinuing altitude exposure and drug treatment. The results indicate that doses of dexamethasone less than 4 mg twice daily may not be effective prophylactic treatment for AMS. Keywords Altitude sickness.