What medication is used to treat altitude sickness (Acute Mountain Sickness)?

From the Guidelines

For altitude sickness prevention and treatment, acetazolamide (Diamox) is the primary medication recommended, typically taken at 125-250mg twice daily starting 24-48 hours before ascent and continuing for 48 hours after reaching your highest altitude. This recommendation is based on the most recent and highest quality study available, which emphasizes the importance of proper acclimatization and medication in preventing altitude sickness 1.

Key Considerations

• Acetazolamide works by causing mild metabolic acidosis, which stimulates breathing and improves oxygen levels, helping the body adjust to lower oxygen environments faster than natural acclimatization alone.
• Dexamethasone can be used as an alternative at 4mg every 6 hours, particularly for those who cannot tolerate acetazolamide.
• For treatment of acute mountain sickness symptoms, ibuprofen or acetaminophen can help with headaches, while ondansetron may relieve nausea.
• Proper acclimatization remains essential, including ascending gradually (no more than 1,000-1,500 feet per day above 8,000 feet), staying hydrated, avoiding alcohol, and following the "climb high, sleep low" principle.

Special Considerations for Women

• Women may have a higher risk of acute mountain sickness, and pre-acclimatization, slow ascent, and potentially pharmacological prevention (acetazolamide) are recommended 1.
• Respiratory muscle training prior to or during altitude/hypoxic sojourn may be more beneficial for women due to larger expiratory flow limitations during hyperventilation 1.
• Early and appropriate iron supplementation prior to and during altitude/hypoxic sojourn is recommended due to a higher risk of iron deficiency in women 1.

Monitoring and Descent

• If symptoms worsen despite medication (severe headache, confusion, difficulty walking, shortness of breath at rest), immediate descent is necessary as severe altitude sickness can be life-threatening.
• Monitoring of hypoxemia and appropriate reduction of training intensity during chronic altitude/hypoxia exposure is recommended, especially for women who may experience greater hypoxemia and decrease in VO2max 1.

From the Research

Altitude Medication

• Acetazolamide is a commonly used medication for the prevention and treatment of acute mountain sickness (AMS) 2, 3, 4, 5, 6
• The recommended dose of acetazolamide varies, with studies suggesting doses of 125 mg twice daily 2, 250 mg twice daily or 500 mg slow release once daily 3, and 500-750 mg/day for rapid ascents to altitudes >3,500 m 4
• A lower dose of 62.5 mg twice daily has been shown to be noninferior to the standard dose of 125 mg twice daily for the prevention of AMS 5
• Pre-treatment with acetazolamide on the day before ascending to high altitude may reduce AMS incidence on the first day at high altitude, but improved oxygen availability to tissues may not occur until the second day of exposure 6
• The timing of acetazolamide pre-treatment is important, with some studies suggesting that starting treatment at least two days before arrival at high altitude may be more beneficial for preventing AMS development 6

Acetazolamide Efficacy

• Acetazolamide has been shown to be effective in decreasing the incidence and severity of AMS during rapid ascents 2, 4
• The medication improves gas exchange and exercise performance, and reduces the symptoms of AMS in most individuals 3
• However, the efficacy of acetazolamide may depend on the dose and timing of administration, as well as individual factors such as altitude and physical activity level 2, 4, 5, 6

Alternative Medications

• Dexamethasone is another medication that can be used for the prevention and treatment of AMS, although it is typically used for short-term treatment or prevention and should not be used for more than 2-3 days 3
• Progesterone has also been suggested as a potential prophylactic treatment for AMS, although more research is needed to confirm its efficacy 3