Objective: To determine the impact of sumatriptan prophylaxis on acute mountain sickness (AMS) and altitude headache development within 24 hours of ascent, we designed a double-blind, randomized, clinical trial. Methods: A prospective, double-blind, randomized, placebo-controlled trial was conducted in Tochal Mountain Hotel at an altitude of 3,500 meters above sea level during October 2006 to November 2006. A total of 102 Iranian adults were assigned to receive either sumatriptan succinate (50mg) or placebo within I hour of ascent. AMS incidence was measured by Lake Louise AMS score >= 3 with headache and one other symptom. Secondary outcome measures included severity of syndrome (Lake Louise scores >= 5), incidence of headache, and severity of headache. Results: Based on intention-to-treat analysis, AMS was more prevalent in placebo group (n = 23 [45.1%]) than sumatriptan group (n = 12 [23.5%]; p = 0.02). Headache also had a greater rate for placebo users (placebo vs sumatriptan group: 29 [56.9%] vs 17 [33.3%]; P = 0.02). No association was detected between sumatriptan prophylaxis and AMS or altitude headache severity. Discussion: Sumatriptan prophylaxis is effective to prevent AMS development. Furthermore, our findings confirm cerebral vasodilative and edematous mechanisms of AMS progression, whereas sumatriptan is a selective 5-hydroxytryptamine(1) receptor subtype agonist and a selective cerebral vasoconstrictor as a result (http://www.controlled-trials.com/ISRCTN87201238/).
