Heading out for a family ski trip. Going hiking during school break. Sightseeing in a mountainous region. Your hotel is booked, and the itinerary is set. But one thing you may not think to pack along with those skis, sneakers, and sunscreen are some helpful tips on how to avoid altitude sickness.

It is easy to overlook altitude sickness, also known as acute mountain sickness (AMS), when you travel. The illness, which can vary from uncomfortable to life-threatening, occurs when you ascend in altitude too quickly.

The higher you climb in elevation, the less air pressure and oxygen is in the atmosphere. Some people are more sensitive to this feeling than others and begin to experience symptoms like headache, fatigue, and dizziness. This can progress to nausea and vomiting, shortness of breath, or confusion.

“Anyone can get altitude sickness, despite their age and level of physical fitness,” explains Carolyn Mudry, DO, internist at Summit Health. “It occurs when someone goes from a low altitude to a high altitude, such as leaving New Jersey to ski in Colorado’s tall mountains. It does not occur on airline flights, however, since the cabins are pressurized.” Compared to flying, however, driving gives your body more time to adjust with a more gradual incline.

Altitude sickness typically kicks in when you are at least 7,000 feet above sea level. New York City, for example, is only 33 feet above sea level compared to the Rocky Mountain ski slopes that are 11,000 feet or higher. People who are pregnant, have heart or lung conditions, or live at low elevations may be more prone to develop the condition.  

Symptoms generally start within the first 24 hours of being at a new elevation. They usually improve in a day or two after the body has time to adjust.

The most important thing you can do to feel better is return to a lower elevation. Over-the-counter painkillers can help with headaches, while prescription medications can control nausea and vomiting.

“Descending to lower altitudes will improve altitude sickness,” explains Dr. Mudry. “We also recommend a high dose of the medication acetazolamide.”

Altitude sickness can be dangerous and life-threatening if not treated properly, she cautions. In serious cases, fluid can build up in the lungs and brain. If any of your symptoms become extreme, or you continue to have shortness of breath, see a physician immediately. They will listen to your lungs and take an X-ray of the chest or CT scan of the brain if needed.

High altitude pulmonary edema (HAPE) is a condition that causes pressure to build up in the lungs and fluid to leak out of the blood vessels. Signs of HAPE include shortness of breath and a cough with white or pink frothy mucus.

Swelling can also develop in the brain, a condition known as high altitude cerebral edema (HACE). Visit the emergency room if you experience a severe headache, difficulty walking, loss of coordination, or confusion.

“With severe altitude sickness, as in HAPE or HACE, descending to low altitudes is a must,” advises Dr. Mudry.

Tips to Avoid Altitude Sickness

Unless you are an avid mountain climber or skier, you probably don’t think twice about altitude sickness. Here are some tips to keep you healthy on your next vacation.

Go slow. The body needs to adjust gradually to changes in elevation. Do not start your trip above 10,000 feet, especially if you live at a low altitude the rest of the year. Increase your climb by no more than 1,000 feet a day. Take a rest day for every 3,000 feet you ascend.

Sleep low. If you spend a lot of time at high elevations during the day or climb more than 1,000 feet in a day, make sure to rest at a low altitude. Remember the climbers’ motto: “climb high and sleep low.”

Rest up. At the first sign of trouble, come down in elevation. Take it easy and let your body reset. Do not push yourself to climb higher.

Wait to exercise. Delay that vigorous workout for at least 24 hours. Plan a light activity for day one while your body finds its bearings.

Hydrate well and avoid stimulants. Drink several quarts of water a day. Good hydration increases your blood oxygen levels. Skip alcohol, tobacco, and sleeping pills, which can be taxing for your body to process.

Carb load. Fill your plate with pasta, bread, and foods that are rich in potassium. Carbohydrates contain sugar, which gives the body energy. You also use less oxygen to break down carbs when compared with fat.

Take medication. Talk to your doctor if you have a history of motion or altitude sickness. A prescription drug called acetazolamide, which is taken preventively a day or two before you travel, can help curb symptoms. The medication helps the body use oxygen more efficiently.