What medication is recommended for altitude sickness?

Medication for Altitude Sickness

Acetazolamide is the first-line medication recommended for prevention and treatment of altitude sickness, with a typical prophylactic dose of 125-250 mg twice daily starting the day before ascent. 1

Prevention of Acute Mountain Sickness (AMS)

Recommended Medications:

1. Acetazolamide (First-line):

   • Dosage: 125-250 mg twice daily
   • Timing: Start 24 hours before ascent and continue for 2-3 days at high altitude
   • Mechanism: Carbonic anhydrase inhibitor that increases ventilation and arterial oxygenation
   • Evidence: Significantly reduces AMS incidence from 35-50% to approximately 10-20% 2

2. Alternatives when acetazolamide is contraindicated:

   • Dexamethasone: 4 mg every 6 hours
   • Nifedipine: Extended-release 20 mg three times daily (primarily for those with history of High Altitude Pulmonary Edema) 1

Dosing Considerations:

• Standard prevention: 125 mg twice daily is effective for most travelers
• Higher risk scenarios (rapid ascent above 3500m): Consider 500-750 mg/day divided doses 3
• Day-of-ascent dosing: Can be effective but slightly less so than starting the day before 4

Treatment of Established Altitude Sickness

For Mild to Moderate AMS:

• Acetazolamide: 250 mg twice daily
• Rest and acclimatization: Delay further ascent until symptoms resolve
• Hydration: Maintain adequate fluid intake

For Severe AMS or High Altitude Pulmonary Edema (HAPE):

• Immediate descent (primary treatment)
• Supplemental oxygen when available
• Nifedipine: 20 mg extended-release every 8 hours for HAPE 1
• Dexamethasone: 8 mg initially, then 4 mg every 6 hours for cerebral edema

Non-Pharmacological Prevention Strategies

• Gradual ascent: Maximum 300-600 m/day above 2500 m 1, 5
• Rest day: Include one rest day for every 600-1200 m gained
• Avoid overexertion: Particularly during the first 24-48 hours at altitude
• Maintain hydration: Avoid alcohol during initial acclimatization

Special Populations

Cardiovascular Patients:

• Acetazolamide may reduce the risk of subendocardial ischemia at high altitude 1
• Patients with coronary artery disease should consult their physician before high altitude travel

Women:

• May have higher risk of AMS than men
• Pre-acclimatization and slow ascent particularly important
• Consider iron supplementation before altitude exposure due to higher risk of iron deficiency 1

Common Pitfalls and Caveats

• Acetazolamide is not a substitute for proper acclimatization
• Side effects of acetazolamide include:
  • Paresthesias (tingling) in extremities
  • Altered taste of carbonated beverages
  • Increased urination
  • Potential for sulfa allergy reactions
• Combining acetazolamide with other diuretics may increase risk of dehydration and electrolyte imbalances 1
• Timing matters: Starting acetazolamide the night before ascent is more effective than day-of-ascent dosing 4

Remember that the most effective intervention for severe altitude illness is immediate descent to lower altitude, regardless of medication use.