How does Diamox (acetazolamide) help with altitude sickness?

How Diamox (Acetazolamide) Helps with Altitude Sickness

Diamox (acetazolamide) helps prevent altitude sickness by inhibiting carbonic anhydrase, which increases ventilation, improves oxygenation, and accelerates acclimatization to high altitude environments. 1

Mechanism of Action

Acetazolamide works through several physiological mechanisms to prevent and treat altitude sickness:

1. Respiratory Stimulation:

   • Inhibits carbonic anhydrase enzyme in the kidneys and red blood cells
   • Creates a mild metabolic acidosis by increasing bicarbonate excretion
   • The acidosis stimulates the respiratory center to increase ventilation rate
   • Higher ventilation improves oxygen uptake at high altitudes

2. Improved Oxygenation:

   • Increases arterial oxygen saturation (SaO₂) 1
   • Reduces the risk of hypoxemia that triggers altitude sickness symptoms

3. Blood Pressure Regulation:

   • Antagonizes the blood pressure rise induced by high altitude 2
   • Helps prevent central sleep apnea that often occurs at altitude 2

4. Prevention of Fluid Retention:

   • Acts as a mild diuretic, reducing fluid retention in tissues
   • May help prevent cerebral and pulmonary edema associated with severe altitude illness

Effectiveness for Altitude Sickness

Acetazolamide significantly reduces the incidence of Acute Mountain Sickness (AMS):

• Reduces the risk of adverse altitude effects in both healthy individuals and those with underlying conditions 3
• The number needed to treat (NNT) to prevent one case of AMS in healthy adults is 10 3
• Particularly effective for rapid ascents to altitudes above 3350m, where AMS risk can reach 35-50% 4

Dosage for Altitude Sickness Prevention

• Standard preventive dosage: 125-250 mg twice daily 1
• When to start: Begin 24 hours before ascent to high altitude 1
• Higher dosages: 500-750 mg/day may be more effective for rapid ascents over 3500m 1

Limitations and Considerations

• While effective for AMS prevention, acetazolamide shows limited efficacy in preventing High Altitude Pulmonary Edema (HAPE) compared to medications like dexamethasone, tadalafil, or nifedipine 5
• Does not significantly reduce pulmonary artery pressure despite improving arterial oxygenation 5
• Should be used alongside proper acclimatization strategies, not as a substitute 1

Common Side Effects

• Paresthesias (tingling sensations, especially in extremities)
• Altered taste (particularly for carbonated beverages)
• Increased urination
• Fatigue and drowsiness

Important Precautions

• Contraindicated in patients with:

  • Sulfa allergy
  • Severe kidney or liver disease
  • History of kidney stones
  • Adrenocortical insufficiency
  • Hyperchloremic acidosis 1

• Monitor for electrolyte imbalances and acid-base disturbances with prolonged use

Best Practices for Altitude Sickness Prevention

Acetazolamide should be part of a comprehensive approach:

1. Gradual ascent: Not exceeding 300-600m/day above 2500m 1
2. Rest days: Include one rest day for every 600-1200m gained 1
3. Hydration: Maintain adequate fluid intake
4. Medication: Use acetazolamide as prescribed for prevention
5. Immediate descent: Primary treatment for severe altitude illness 1

Acetazolamide remains one of the most effective pharmacological interventions for preventing altitude sickness when combined with appropriate acclimatization strategies.