Analgesic drugs like
acetylsalicylic acid,
paracetamol, and
ibuprofen are frequently used by subjects suffering from
headache of acute
mountain sickness (AMS). It is not clear if the effect is due to
analgesia or prevention of AMS. We performed a randomized controlled clinical trial comparing a low dose of an
acetylsalicylic acid analog,
calcium carbasalate (380 mg /day), to placebo in a cohort of altitude-naïve subjects attempting a fast climb of Mt. Kilimanjaro (5896 m). A third noncontrolled open arm was proposed-the usual recommended preventive treatment of
acetazolamide 500 mg/day. Of 93 potential participants, 44 chose prevention with
acetazolamide, 18 refused participation, 15 received
calcium carbasalate, and 16 received placebo. Mean age was 39 +/- 9 (SD) yr and 15% were female. AMS was quantified by the Lake Louise Symptom Score and physician assessment.
Calcium carbasalate at 380 mg/day did not have any preventive effect on AMS and did not have any effect on the prevalence and intensity of
headache. Event rate of AMS in the pooled carbasalate-placebo group was 84% and 55% in the
acetazolamide group. The number needed to treat (NNT) at 500 mg/day of
acetazolamide was 3. One subject on
acetazolamide developed high altitude
cerebral edema and was treated with
dexamethasone,
oxygen, and descent by evacuation. In conclusion, low-dose
calcium carbasalate is not effective for prevention of AMS. In addition, these results corroborate the contention that in typical steep climbing profile settings, such as used by commercial enterprise on Mt. Kilimanjaro,
acetazolamide 500 mg/day may not be sufficient to prevent AMS or to sufficiently reduce symptom intensity in almost half of subjects.