Are coca leaves effective for preventing or treating altitude sickness?

Coca Leaves for Altitude Sickness: Evidence-Based Assessment

Coca leaves are not effective for preventing or treating altitude sickness, and acetazolamide remains the most evidence-based pharmacological intervention for prevention of altitude sickness. 1

Understanding Altitude Sickness

Altitude sickness, also known as acute mountain sickness (AMS), occurs due to hypobaric hypoxia when ascending to elevations typically above 2500m. It can progress to more severe forms including high-altitude pulmonary edema (HAPE) and high-altitude cerebral edema (HACE), which can be life-threatening.

Pathophysiology

• Decreased oxygen tension at altitude triggers hypoxic pulmonary vasoconstriction
• This leads to increased pulmonary vascular resistance and potential pulmonary hypertension
• Symptoms result from tissue hypoxia and compensatory mechanisms 2

Evidence Against Coca Leaves

Recent research specifically examining coca leaf use for altitude sickness prevention shows:

• A 2022 cohort study of travelers to Cusco, Peru (3350m) found that consumption of coca leaf tea was not associated with decreased risk of AMS 1
• Another study in Peru found that coca leaf products were used by 62.8% of travelers but were actually associated with increased AMS frequency rather than prevention 3

Effective Prevention Strategies

Pharmacological Prevention:

1. Acetazolamide (First-line):

   • Significantly reduces AMS risk with an odds ratio of 0.13 (0.03-0.56) 1
   • Recommended for those with history of AMS or rapid ascent profiles
   • Works by increasing arterial oxygen levels and reducing symptoms 4
   • Often underprescribed (only 16.6% of travelers used it in one study) 3

2. Dexamethasone:

   • Effective alternative, particularly for severe AMS prevention
   • Has some euphoric effects that may mask symptoms 4
   • Generally reserved for treatment rather than prevention

3. Nifedipine:

   • Primarily for HAPE prevention in susceptible individuals
   • Particularly useful for those with history of HAPE 2

Non-Pharmacological Prevention:

1. Gradual Ascent:

   • Most effective prevention strategy
   • Recommended rate above 2500m is 300-600m per day 2
   • Include rest days (one day for every 600-1200m gained)

2. Proper Acclimatization:

   • Spending time at intermediate altitudes before going higher
   • Avoiding vigorous exertion before acclimatizing

3. Adequate Hydration

Risk Factors for Altitude Sickness

The following factors increase susceptibility:

• Obesity (OR 14.45) 1
• Female sex (OR 4.32) 1
• Rapid ascent profiles
• No recent high altitude exposure
• Age under 60 years 3

Treatment Approach

For established altitude sickness:

1. Descent - most effective treatment for moderate to severe cases
2. Supplemental oxygen when available
3. Acetazolamide - can help treat mild AMS
4. Dexamethasone - for more severe AMS and HACE
5. Nifedipine or PDE-5 inhibitors - for HAPE 5

Special Considerations

• Pre-existing conditions: Patients with cardiopulmonary disease, especially pulmonary hypertension, are at higher risk 2
• Children: May be more susceptible to altitude illness, with similar prevention and treatment approaches 2
• Timing: AMS typically develops within 6-12 hours of ascent, with symptoms peaking at 24-48 hours

Common Pitfalls

1. Relying on unproven remedies: Despite cultural traditions and widespread use, coca leaves have not been proven effective and may give travelers a false sense of security
2. Inadequate pre-travel preparation: Only 29.1% of travelers receive AMS advice from physicians 3
3. Underutilization of acetazolamide: Despite strong evidence for its effectiveness
4. Ignoring early symptoms: Leading to progression to more severe forms of altitude illness

In summary, travelers should rely on evidence-based strategies including gradual ascent and acetazolamide for prevention of altitude sickness rather than coca leaves, which have not demonstrated effectiveness in clinical studies.