Altitude Sickness: Prevention & Treatment for the Inca Trail

Altitude sickness (known as soroche in Peru) is the most common health concern for travelers to Cusco and the Inca Trail. It occurs when your body hasn't had time to adjust to reduced oxygen levels at high elevation. Here is what you need to know about symptoms, severity, and how to prevent it.

Understanding Altitude Sickness

At sea level, the air contains about 21% oxygen. This percentage doesn't change at altitude, but the air pressure drops, meaning each breath delivers fewer oxygen molecules to your lungs. At Cusco's elevation (3,400m), you're breathing roughly 66% of the oxygen available at sea level. At Dead Woman's Pass (4,215m), it's about 59%.

Your body compensates by breathing faster, producing more red blood cells, and increasing heart rate. This adaptation takes 2–3 days, which is why rushing from sea-level Lima directly to trekking is risky, and why all our packages include acclimatization time.

Symptoms by Severity

Mild AMS (Acute Mountain Sickness)

Affects 50–80% of visitors to Cusco. Not dangerous, but uncomfortable. Symptoms appear 6–24 hours after arrival at altitude:

• Headache (most common symptom)
• Fatigue, weakness, drowsiness
• Dizziness or lightheadedness
• Loss of appetite, mild nausea
• Difficulty sleeping
• Shortness of breath during exertion

Action: Rest, hydrate, take ibuprofen or paracetamol for headache. Symptoms usually resolve within 24–48 hours with proper acclimatization.

Moderate AMS

Requires attention. If mild symptoms worsen or don't improve after 24 hours:

• Severe, persistent headache not relieved by painkillers
• Nausea and vomiting
• Increasing fatigue and weakness
• Shortness of breath at rest
• Decreased coordination

Action: Do not ascend further. Consider descending 300–500m. Take Diamox if not already taking it. Seek medical evaluation. Our guides carry supplemental oxygen and are trained to assess severity.

Severe: HACE & HAPE (Life-Threatening)

Prevention

Acclimatization Schedule

The single most effective prevention is gradual ascent. Our recommended schedule:

• Day 1 (Arrive Cusco, 3,400m): Rest. Short, gentle walks only. Drink coca tea. No alcohol.
• Day 2 (Sacred Valley, 2,800m): Day trip to the Sacred Valley, 600m lower than Cusco. Gentle sightseeing at Pisac and Ollantaytambo.
• Day 3 (Cusco, 3,400m): Light city sightseeing. Walk to San Blas, visit markets. Your body is already adapting.
• Day 4+ (Trek begins): You've had 2+ days to acclimatize. The first trek day starts at 2,650m, lower than Cusco.

Medication: Diamox (Acetazolamide)

Diamox is a carbonic anhydrase inhibitor that speeds acclimatization by making your blood slightly more acidic, which triggers deeper breathing and better oxygen uptake.

• Dosage: 125–250mg twice daily (morning and evening)
• When to start: 1–2 days before arriving at altitude
• Duration: Continue for 2 days after reaching your highest altitude
• Side effects: Tingling in fingers/toes/lips, increased urination, altered taste of carbonated drinks, mild drowsiness
• Contraindications: Sulfa allergy, kidney disease. Consult your doctor before travel.

Alternatives: If you can't take Diamox, ask your doctor about dexamethasone (for prevention) or nifedipine (for HAPE prevention). Ibuprofen (600mg three times daily) has shown some preventive benefit in studies.

General Prevention Tips

• Hydrate aggressively: Drink 3–4 liters of water daily at altitude. Dehydration mimics and worsens altitude symptoms.
• Avoid alcohol: For at least the first 24–48 hours. Alcohol dehydrates and depresses breathing.
• Eat light, high-carb meals: Your body metabolizes carbohydrates more efficiently at altitude than fats or proteins.
• Ascend gradually: Never gain more than 500m sleeping altitude per day above 3,000m.
• Coca tea: Widely used in Peru. May provide mild symptomatic relief. Available everywhere in Cusco.

Risk Factors

You may be more susceptible to altitude sickness if you:

• Have had altitude sickness before (the strongest predictor)
• Live at or near sea level
• Ascend rapidly without acclimatization
• Have respiratory conditions (asthma, sleep apnea)
• Are under 50 (younger adults tend to ascend faster and push harder)

Note: Physical fitness does not prevent altitude sickness. Marathon runners and sedentary travelers are equally susceptible.

Our Tours Include Acclimatization

Every Inca Trail package includes 2–3 acclimatization days in Cusco and the Sacred Valley (2,800m) before trekking. Our guides carry supplemental oxygen, pulse oximeters, and are trained in high-altitude first aid. Our guides check on every trekker throughout the trek.

Altitude FAQ