What is the proper use of acetazolamide (Diamox) for preventing acute mountain sickness (AMS) at high altitudes?

From the Guidelines

Acetazolamide (Diamox) is recommended for preventing acute mountain sickness (AMS) at a dose of 125-250 mg twice daily, starting 24-48 hours before ascent and continuing for 48 hours after reaching your final altitude, as supported by recent studies 1. The medication works by causing the kidneys to excrete bicarbonate, creating a mild metabolic acidosis that stimulates breathing and increases oxygen levels in the blood, which helps the body acclimatize faster to high altitudes. Some key points to consider when using acetazolamide for AMS prevention include:

• Starting the medication 24-48 hours before ascent to allow for proper acclimatization
• Continuing the medication for 48 hours after reaching the final altitude to ensure adequate protection
• Drinking plenty of water to prevent dehydration and reduce the risk of kidney stones
• Avoiding alcohol and ascending gradually (ideally less than 1,000-1,500 feet per day above 8,000 feet) to minimize the risk of AMS
• Being aware of potential side effects, such as increased urination, tingling in the fingers and toes, altered taste of carbonated beverages, and rarely, nausea, as noted in studies 1. It's also important to note that individuals with a history of sulfa drug allergies should avoid acetazolamide, and that proper acclimatization, gradual ascent, and staying hydrated are crucial in preventing AMS, as highlighted in recent research 1.

From the Research

Proper Use of Acetazolamide for Preventing Acute Mountain Sickness

• Acetazolamide is a commonly used medication for the prevention of acute mountain sickness (AMS) at high altitudes 2, 3, 4, 5, 6.
• The typical dosage of acetazolamide for AMS prevention is 125-250 mg twice daily, with some studies suggesting that higher doses may not provide additional benefits 5, 6.
• Acetazolamide can be administered starting the day or night before ascent, with some evidence suggesting that day of ascent dosing may be effective, although it may have a slightly higher incidence of AMS compared to traditional dosing 2.
• The medication works by increasing arterial oxygen concentrations, reducing proteinuria and peripheral edema, and other objective measures of AMS 3.
• Acetazolamide is also used to treat established AMS, although large doses may be required to increase arterial oxygen levels and reduce symptoms 3.

Administration and Efficacy

• The efficacy of acetazolamide for AMS prevention is limited when the baseline risk is low, and there is some evidence of dose-responsiveness 5.
• The risk of paresthesia, polyuria, and taste disturbance is increased with acetazolamide use, particularly at higher doses 5, 6.
• Acetazolamide prophylaxis is associated with a 48% relative-risk reduction compared to placebo, with a dose of 250 mg/day having similar efficacy to higher doses and a favorable side-effect profile 6.

Comparison with Other Treatments

• There is limited evidence on the effectiveness of acetazolamide compared to other drugs used for treating AMS, such as steroids and calcium channel blocking drugs 3.
• Dexamethasone, used prophylactically, also reduces the symptoms of AMS, partly due to its euphoric effect 3.
• Nifedipine is used to treat high altitude pulmonary edema, while dexamethasone is used to treat high altitude cerebral edema 4.