Huaraz sits at about 3,050 metres above sea level, and many of its finest excursions go above 4,500. For anyone arriving from Lima, Chimbote or any coastal city, that is an abrupt change. Altitude sickness, or soroche, can ruin a trip if ignored, but good planning prevents most of it. This guide summarizes the recommendations of the US CDC and the Wilderness Medical Society and applies them to a real trip in the Cordillera Blanca.
Disclaimer: this article is informational and does not replace advice from a health professional. If you have heart or respiratory conditions, are pregnant or have doubts, see your doctor before travelling.
What is altitude sickness?
As we go up, air pressure drops and less oxygen reaches the blood. The body needs a few days to adapt: it breathes faster, adjusts circulation and over time changes the blood. When we climb faster than the body can adapt, symptoms appear. The CDC say risk becomes relevant above about 2,400–2,500 metres (8,000 feet), so in and around Huaraz it applies to every traveller.
Symptoms of acute mountain sickness
Acute mountain sickness (AMS) is the mildest and most common form. According to the CDC, symptoms include:
- Headache.
- Fatigue.
- Loss of appetite.
- Nausea or vomiting.
In pre-verbal children it may show only as irritability. Mild cases usually improve in a couple of days if you do not go higher. There are much rarer severe forms, such as high-altitude cerebral oedema (confusion, clumsy walking) and high-altitude pulmonary oedema (breathlessness at rest, cough). Both are emergencies requiring immediate descent and medical care.
The golden rule: go up gradually
The CDC and Wilderness Medical Society agree on the essentials:
- Avoid going in a single day from low altitude to sleeping above about 2,750 m.
- Above 3,000 m, do not increase your sleeping altitude by more than about 500 m per day.
- Add an extra acclimatization day for every additional 1,000 m of sleeping altitude.
- Avoid alcohol and strenuous exercise for the first 48 hours.
- Take day trips higher and come back to sleep lower.
What matters most is the altitude where you sleep, not the maximum you reach during the day. That is Huaraz's advantage: you sleep at about 3,050 m and make return trips higher.
The Huaraz problem… and how to solve it
The typical bus from Lima takes you over Conococha, above 4,000 metres, and straight to sleep at over 3,000. Under the CDC risk classification, sleeping between 2,750 and 3,400 m on day one already means moderate risk. That is no reason not to go, but it is a reason to plan:
- Days 1 and 2: relative rest in the city, gentle walks, good hydration, no alcohol.
- Day 2 or 3: low-effort trips such as the Llanganuco lakes or Chavín de Huántar.
- Day 3 or 4: a warm-up hike such as Laguna Churup.
- From day 4 or 5: higher trips such as Pastoruri or Laguna 69.
Some specialist trekking guides recommend at least three days in Huaraz before starting multi-day routes. If you can afford it, more days are always better.
What if I come from Chimbote?
Chimbote is at sea level, so the change is just as big. Some routes from the north coast, such as the one up the Cañón del Pato, cross remote areas with poor roads. Apply the same rules. See also what to see in Chimbote.
Medication: talk to your doctor
The CDC mention that there are medications to prevent AMS and speed acclimatization, and their use depends on each person's risk profile and history. Consult a doctor before the trip, especially if your itinerary does not allow a gradual ascent. Do not self-medicate.
The CDC also note that the small oxygen canisters sold in some destinations may give brief relief but contain too little oxygen for sustained improvement. They are no substitute for acclimatization.
Helpful habits
- Drink water regularly even if not thirsty: highland air is dry.
- Eat light the first days.
- If you usually drink coffee, keep doing so: the CDC warn that caffeine-withdrawal headache can be confused with altitude headache.
- Sleep well and keep warm at night.
- Protect yourself from the sun: radiation is intense at altitude.
- Coca tea: a very common traditional Andean drink. Enjoy it as a local custom, but do not consider it medical treatment.
On a hike: when to turn back
On routes like Laguna 69 or Pastoruri, pay attention to how you feel. With a strong headache, nausea or tiredness out of proportion to the effort, tell the guide, stop climbing and rest. The CDC are clear: anyone with symptoms should not go higher until they resolve, and anyone getting worse at rest must descend. No photo is worth your health.
Travel with formal agencies
SERNANP-authorized agencies, mandatory at Laguna 69 since February 2026, work with identified guides who know the symptoms and evacuation routes. Ask before booking what protocol they follow if someone feels unwell. You can ask us for contact with local operators.
In short
Altitude sickness is common but mostly preventable. Go up slowly, sleep low and climb by day, avoid alcohol and strenuous effort at first, and leave the highest hikes for the end of your trip. For a full plan, read things to do in Huaraz.
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Sources
- CDC – Travel to High Altitudes
- CDC Yellow Book – High-Altitude Travel and Altitude Illness
- CDC Yellow Book 2026 – AMS risk categories table
- Wilderness Medical Society – 2019 clinical practice guidelines
- Horizon Guides – Trekking in Huaraz (acclimatization)
- Andina – Laguna 69 entry only with authorized agencies
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