What is the best way to prescribe acetazolamide (Diamox) to prevent acute mountain sickness (AMS)?

From the Guidelines

Diamox (acetazolamide) should be prescribed at a dose of 125-250 mg twice daily, starting 24-48 hours before ascending to high altitude, to prevent acute mountain sickness (AMS), as recommended by recent studies 1. The standard adult prophylactic regimen is 125 mg twice daily, though some physicians prescribe 250 mg twice daily for larger individuals or those ascending to very high altitudes.

• Common side effects include increased urination, tingling in fingers and toes, and altered taste of carbonated beverages.
• Diamox works by increasing respiratory rate and urinary bicarbonate excretion, which helps accelerate acclimatization to high altitude.
• This medication is particularly recommended for those with a history of altitude sickness, those ascending rapidly (over 1,500 feet per day), or when ascending to elevations above 10,000 feet.
• People with sulfa allergies should avoid Diamox, and those with kidney problems should consult their doctor before taking it.
• It is also important to note that proper acclimatization, gradual ascent, staying hydrated, and avoiding alcohol and smoking are crucial in preventing high altitude illness, including AMS, as highlighted in a recent study 2.
• Additionally, targeted training of the respiratory musculature could be a valuable preparation for altitude training, and sex hormones may influence hypoxia responses, which should be considered when prescribing acetazolamide 1.

From the Research

Prevention of Acute Mountain Sickness (AMS)

To prevent AMS, the following measures can be taken:

• Slow ascent to allow acclimatization, with a climbing rate of 300 to 600 m per day 3
• Spend at least nine or more nights at an altitude higher than 2500 m a.s.l. in the last 30 days before ascent 3
• Pharmacological prophylaxis with acetazolamide, a carboanhydrase inhibitor that increases ventilation 3, 4, 5, 6

Dosage of Acetazolamide

The recommended dosage of acetazolamide for AMS prophylaxis is:

• 250 to 500 mg 12 to 24 hours before ascent 3
• 2 × 250 mg 4

Additional Measures

Other measures that can be taken to prevent or treat AMS include:

• Immediate descent to a lower altitude 4, 5, 6
• Administration of oxygen 5, 6
• Use of dexamethasone for severe AMS 5, 6
• Use of nifedipine for high-altitude pulmonary edema (HAPE) 4, 5, 3, 6