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Travel health: How to combat altitude sickness

Apr 26, 2024
By Jackie Yaris
Man on mountain

Clinical editors:
Martha Strain, RN, Megan Dodson, PA-C

If you’ve ever hiked Machu Picchu, climbed Kilimanjaro, or even skied some particularly intense slopes, you might be familiar with altitude sickness. It’s a common ailment — studies show that 25 percent of people show signs of it at elevations as low as 8,000 feet. In its most benign form, altitude sickness can put a damper on your vacation plans. In more severe manifestations it can be debilitating — and sometimes deadly. If you’re planning to travel to higher elevations, be sure you know how to prevent and treat altitude sickness.

What is altitude sickness?

The phrase “altitude sickness” is an umbrella term for several varieties of illness. The root cause is the same, however: lack of oxygen at high elevations. The symptoms vary, but can include headache, loss of appetite, vomiting, diarrhea, and abdominal pain, all of which can last anywhere from 12 hours to four days.

What are the different types?

Altitude sickness is typically divided into three distinct syndromes:

  • Acute Mountain Sickness (AMS): Considered the most common form, AMS involves the symptoms people typically associate with altitude sickness and hangovers: headache, fatigue, loss of appetite, nausea, and occasional vomiting. Symptoms usually resolve within 24 to 72 hours of acclimatization.
  • High Altitude Cerebral Edema (HACE): If AMS progresses, it can turn into HACE, which involves the build-up of fluid in the brain. Symptoms include headache, dizziness, blurry vision, and disorientation. Although an important prevention and treatment strategy is hydration, people with more severe forms of altitude sickness often can’t keep water down. HACE is rare but potentially fatal, and can become life-threatening in just a few hours. Descent is the only real treatment.
  • High Altitude Pulmonary Edema (HAPE): HAPE typically occurs at higher elevations and involves a build-up of fluid in the lungs. HAPE can happen to anyone at any altitude above 8,000 feet. Even experienced athletes can experience it, so while preparation and training are important, they aren’t guaranteed safeguards. Mild symptoms can include a dry cough and shortness of breath after mild exertion, but more severe types of HAPE involve shortness of breath at rest, confusion, and fever. The only way to alleviate HAPE is to descend — oxygen and descent are life-saving and essential.

How can I prevent altitude sickness?

Luckily, there are ways to sidestep the symptoms of altitude sickness and avoid the more serious complications before and during your trip.

Before you go:

Talk to your healthcare provider

Certain medical conditions can make people more likely to get seriously ill from altitude changes, so it’s best to talk to your healthcare provider before you climb.


Drink two to three liters of water a day to prepare for your trip. Dehydration decreases the body’s ability to acclimatize to higher altitudes.


If you are a regular coffee drinker, make sure that you have caffeine prior to climbing. The effects of caffeine withdrawal mimic the effects of altitude sickness, and are alleviated by caffeine.

Stay home if you’re sick

What seems to be a small cold at lower elevations can be serious at higher elevations. It’s imperative to be completely healthy when you begin your journey. Your lungs are already working their hardest to adapt to the thinner air at altitude; any cough or wheeze can compromise that. Use your best judgment and if you’re unsure about whether it’s safe to go, contact your health care provider for advice.

Special Health Considerations

Those with certain high risk medical conditions and those that are pregnant should review their high altitude itinerary with their provider or specialist to determine overall safety in ascending. If you think you might be at risk, make an appointment to decide together if this is the right trip for you.

Take the right medication

Acetazolamide is a medication often used to prevent and reduce the symptoms of altitude sickness by making you breathe faster and helping you use oxygen better. Acetazolamide should get started 24 hours before you begin climbing. Side effects include dizziness, increased urination, and tingling in the hands and feet. People with certain medical conditions can’t take acetazolamide, so speak to your healthcare provider about whether it’s right for you, or whether you should consider an alternative such as ibuprofen.

Bring snacks

Because it’s important that you continue to eat while at altitude, make sure you are bringing food that is easily tolerated. Treats like chocolate or snacks such as pretzels can be great portable options. Stick with simple flavors; sometimes spicy food can be very nauseating at high altitudes.

During the trip:


Don’t go too high too fast. Acclimatization is the most important way to avoid symptoms of altitude sickness, so plan for a night or two at 8,000 feet, then ascend no more than 1,600 feet per day.

Climb high, sleep low

The old climber’s adage holds true: climb high, sleep low. It’s important to head to higher altitudes during the day as you are trying to acclimatize, but to sleep lower in order to get oxygen. Never sleep at an altitude if you are feeling symptoms of altitude sickness; head down the mountain to sleep in thicker air.

Hydrate more

You’ll know if you’re drinking enough water if you’re urinating regularly. If you haven’t urinated in three to four hours, drink more. Higher altitudes require maintaining regular fluid consumption without forcing overhydration.

Cover up

Protect yourself from the sun by wearing a hat, lip protection, and sunblock. Be sure to wear sunglasses as well to avoid snow blindness, a condition that can occur at higher elevations.

Keep an eye on children

Kids can develop altitude sickness the same as adults. For those that are preverbal, look for irritability, loss of appetite, or an ill appearance.

If you get sick

If, despite your best efforts, you do begin to feel some of the mild signs of altitude sickness like headache and difficulty breathing, there are a few strategies you can try. Often you can alleviate the symptoms with a few simple tricks:

  1. Hydrate with water and electrolyte solutions.
  2. Take a dose of ibuprofen if considered safe per your medical history.
  3. Walk slower, especially while climbing. Try this pattern: Step, step…breathe….step, step…breathe. Sometimes all you need to do is slow down.

If the headache and difficulty breathing continue despite all of the above, or if you have severe symptoms, the most important thing you can do is descend. Never ever try to “sleep it off” — that could be a deadly decision. Remember, the mountain will always be there.

Originally published November 20, 2018.

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Jackie Yaris

The One Medical blog is published by One Medical, a national, modern primary care practice pairing 24/7 virtual care services with inviting and convenient in-person care at over 100 locations across the U.S. One Medical is on a mission to transform health care for all through a human-centered, technology-powered approach to caring for people at every stage of life.

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