What is altitude sickness?

Altitude sickness refers to a combination of symptoms that can result when you take in less oxygen than your body is used to. This happens when you travel to a high elevation (8,000 feet or higher).

It's commonly believed that there's less oxygen the higher up you go. In fact, the concentration of oxygen in the air is the same on top of a mountain as it is at the beach, but the air pressure is much lower.

The lower the air pressure, the less oxygen you take in with each breath. If your body isn't used to functioning on this amount of oxygen, you may start to feel sick.

Altitude sickness can happen to anyone, regardless of age or fitness level, and some people are simply more susceptible to it than others. People who live at higher altitudes – and those who stay there for a while – get used to taking in less oxygen and do just fine. But those who change elevations quickly, especially when they're being physically active, often have trouble.

Types of altitude sickness

There are several types of altitude sickness.

Acute mountain sickness (AMS) is the mildest, most common type. Less common and much more serious forms occur when AMS progresses, or when someone with AMS continues to ascend without giving his body a chance to adjust.

These conditions cause fluid to accumulate in the brain – known as high altitude cerebral edema (HACE) – or in the lungs, known as high altitude pulmonary edema (HAPE).

Altitude sickness in children

It's unlikely that your child will suffer from altitude sickness, but if you're planning to travel to higher elevations, you may want to take your time getting there.

If you're driving from San Francisco (at sea level) to Denver (at 5,000 feet), for example, your child probably won't have any trouble with altitude sickness. But if you're planning to fly from a low elevation to an elevation that's 8,000 feet or higher, you may want to take a few days to get there, spending a night or two at an intermediate elevation. Then allow one day for every 1,000 feet you travel beyond 8,000 feet.

If your child has a chronic heart or lung disease, though, or any systemic disease that affects breathing, it's a good idea to check with her doctor before bringing her to a high altitude. Also chat with the doctor if your baby is younger than 6 weeks of age, because babies this young are more susceptible to altitude sickness.

How can I tell if my child has altitude sickness?

It's not easy to identify altitude sickness because the symptoms are pretty nonspecific at first. They can show up as early as one or two hours after arrival at the higher elevation, but typically they begin to appear eight to 36 hours after arrival.

You may notice a change in your child's normal behavior. For example: He may have trouble eating or sleeping. He may become unusually irritable. He may have a headache, dizziness, or fatigue. He may have difficulty breathing when he exerts himself. He may also have nausea and vomiting.

If your child develops more severe altitude sickness, he might be confused, and his complexion might be pale or blue. He might develop a cough, have difficulty walking, and be short of breath, even when resting. If he's been vomiting, he may also show signs of dehydration.

What can I do to ease his symptoms?

If your child is showing only minor signs of acute mountain sickness, you can take her to a lower altitude to help her acclimate more gradually. Symptoms usually subside in a couple of days.

In the meantime, offer plenty of fluids to keep her well hydrated. You can give her frequent small sips of water or an electrolyte replacement solution to prevent dehydration, especially if she's vomiting.

If she has a headache, you can give her the proper dose of acetaminophen or (if she's 6 months or older) ibuprofen. (If your child is younger than 3 months, check with her doctor before giving her any medications, including over-the-counter options.)

You can also encourage your child to breathe more deeply and at a slightly faster rate than normal, to get more oxygen.

What if the symptoms are more severe?

If your child has difficulty breathing or turns blue, or shows anything more than very minor discomfort, take him to the nearest emergency room. There they can measure the oxygen in his blood and find out if he's suffering from altitude sickness. If his symptoms are severe, he may also need blood tests, a CT scan, a chest X-ray, or an ECG.

If he has AMS, they'll probably give him oxygen and advise you to take him to a lower elevation. If he has HACE or HAPE, he'lll need treatment and close monitoring, as these can be life-threatening conditions.