Altitude sickness facts for kids

Kids Encyclopedia Facts

Quick facts for kids Altitude sickness
Synonyms	High-altitude sickness, altitude illness, hypobaropathy, altitude bends, soroche

Altitude sickness warning – Indian Army
Symptoms	Headache, vomiting, feeling tired, trouble sleeping, dizziness
Complications	High-altitude pulmonary edema (HAPE), high-altitude cerebral edema (HACE)
Usual onset	Within 24 hours
Types	Acute mountain sickness, high-altitude pulmonary edema, high-altitude cerebral edema, chronic mountain sickness
Causes	Low amounts of oxygen at high elevation
Risk factors	Prior episode, high degree of activity, rapid increase in elevation
Diagnostic method	Based on symptoms
Similar conditions	Exhaustion, viral infection, dehydration, carbon monoxide poisoning
Prevention	Gradual ascent
Treatment	Descent to lower altitude, sufficient fluids
Medication	Ibuprofen, acetazolamide, dexamethasone, oxygen therapy
Frequency	20% at 2,500 metres (8,000 ft) 40% at 3,000 metres (10,000 ft)

Altitude sickness, also called acute mountain sickness (AMS), is a problem that can happen when people go to high places too quickly. It's caused by not having enough oxygen in the air at high elevations. Your body needs time to get used to these changes.

Symptoms of altitude sickness can include headaches, feeling sick to your stomach, tiredness, confusion, trouble sleeping, and dizziness. Sometimes, mild altitude sickness can become more serious. This includes high-altitude pulmonary edema (HAPE), which affects your lungs, or high-altitude cerebral edema (HACE), which affects your brain. If you stay at high altitudes for a very long time, you might even get chronic mountain sickness.

Altitude sickness usually happens above 2,500 metres (8,000 ft) (about 8,200 feet). However, some people feel sick at lower heights. Things that increase your risk include having had altitude sickness before, doing a lot of physical activity, or going up too fast. Being very fit does not protect you from getting it. Doctors usually diagnose it based on your symptoms. If you have a headache, feel sick, or are short of breath at high altitude, it's best to assume it might be altitude sickness.

You can prevent altitude sickness by going up slowly. Try not to climb more than 300 metres (1,000 ft) (about 1,000 feet) higher each day. If you feel sick, going down to a lower altitude and drinking enough fluids can help. For mild cases, medicines like ibuprofen can ease symptoms. More serious cases might need oxygen therapy or a special portable bag that creates more pressure. The best way to treat severe altitude sickness is to go down to a lower elevation right away.

About 20% of people get AMS if they go quickly to 2,500 metres (8,000 ft). This number goes up to 40% at 3,000 metres (10,000 ft). Both boys and girls get AMS and HACE equally. However, HAPE is more common in boys. People have known about altitude sickness for a long time. An ancient Chinese text from around 30 BCE described "Big Headache Mountains." This might have been about the Karakoram Mountains.

What Are the Signs and Symptoms?

Left: A woman at normal altitude. Right: The same woman with a swollen face while trekking at high altitude (Annapurna Base Camp, Nepal; 4,130 m (13,550 ft)).

Everyone reacts differently to high altitudes. For some healthy people, mild altitude sickness can start around 2,000 metres (6,600 ft) (about 6,500 feet). This is the height of many mountain ski resorts. Symptoms often appear within ten hours of going up. They usually go away within two days. Sometimes, though, they can become more serious.

Common symptoms include:

Headaches
Feeling confused
Tiredness
Upset stomach
Dizziness
Trouble sleeping

Doing a lot of exercise can make these symptoms worse.

Main Symptoms to Watch For

Headaches are the most common sign of altitude sickness. However, headaches can also mean you are dehydrated. If you have a headache above 2,400 metres (7,900 ft) (about 7,900 feet), along with any of these other symptoms, it might be altitude sickness:

Stomach problems: Not feeling hungry, feeling sick, throwing up, or having a lot of gas.
Feeling tired or weak: Headaches, dizziness, feeling lightheaded, trouble sleeping, or a "pins and needles" feeling.
Swelling: Your hands, feet, or face might swell up.
Breathing issues: Nosebleeds or feeling short of breath when you move around.
Fast heartbeat: Your heart might beat very quickly all the time.
General unwell feeling: Just feeling generally sick or unwell.

Serious Symptoms That Need Help

Some symptoms mean altitude sickness is becoming very dangerous. You need to get help right away if you notice:

Symptoms like a bad cold or bronchitis.
A cough that won't stop and is dry.
Fever.
Feeling short of breath even when you are resting.
A headache that won't go away with pain medicine.
Trouble walking steadily.
Slowly losing consciousness or becoming very confused.
Feeling more and more sick to your stomach and throwing up more often.
Problems with your eyesight.

The most serious problems from altitude sickness happen when fluid builds up in your body. At very high altitudes, this can lead to high-altitude pulmonary edema (HAPE) in your lungs. It can also cause high-altitude cerebral edema (HACE) in your brain. HAPE can get worse very quickly and can be deadly. Symptoms include extreme tiredness, severe shortness of breath even when resting, and a cough. This cough might start dry but could later produce pink, foamy spit. Going down to a lower altitude helps HAPE symptoms.

HACE is also very dangerous and can lead to a coma or death. Symptoms include headaches, tiredness, blurry vision, problems with your bladder or bowels, losing coordination, or confusion. Going down to a lower altitude can save people with HACE.

Why Does Altitude Sickness Happen?

Climbers on Mount Everest often experience altitude sickness.

Altitude sickness can start at 1,500 metres (4,900 ft) (about 5,000 feet). It becomes very serious at extreme heights, above 5,500 metres (18,000 ft) (about 18,000 feet). You can only stay above 6,000 metres (20,000 ft) (about 20,000 feet) for short times. You need extra oxygen to avoid getting sick there.

As you go higher, there is less air pressure. This means there is less oxygen available for you to breathe. Even though the percentage of oxygen in the air stays the same (about 21%), the air is thinner. This makes it harder for your body to get the oxygen it needs.

You can also lose more water vapor from your lungs at higher altitudes. This can lead to dehydration, which can make altitude sickness worse.

How fast you go up, how high you go, how much you exercise, and your own body's reaction all affect if you get sick. They also affect how bad the sickness will be. Altitude sickness usually happens after going up quickly. You can often prevent it by climbing slowly. In most cases, symptoms are temporary. They usually go away as your body gets used to the altitude. But in very serious situations, altitude sickness can be deadly.

High altitude illness is grouped by how high you are:

High altitude: 1,500–3,500 metres (4,900–11,500 ft) (about 5,000 to 11,500 feet).
Very high altitude: 3,500–5,500 metres (11,500–18,000 ft) (about 11,500 to 18,000 feet).
Extreme altitude: Above 5,500 metres (18,000 ft) (above 18,000 feet).

High Altitude (1,500 to 3,500 meters)

At these heights, your body starts to feel the effects of less oxygen. You might not be able to exercise as well. You will also breathe faster. Your blood still carries enough oxygen, usually above 90%. Altitude sickness is common here because many people go up quickly to these heights.

Very High Altitude (3,500 to 5,500 meters)

At very high altitudes, the oxygen in your blood drops below 90%. You might have very low oxygen levels during exercise or sleep. Serious altitude sickness happens most often in this range.

Extreme Altitude (Above 5,500 meters)

Above 5,500 metres (18,000 ft), your body has very low oxygen. Your body's functions get worse over time, even if you try to get used to it. Because of this, people do not live permanently above 5,100 metres (16,700 ft) (about 16,700 feet). You need time to get used to these extreme heights. Going up suddenly without extra oxygen for more than a short time can cause severe altitude sickness.

How Does Your Body React?

When you are at high altitude, there is less air pressure. This means that even though the air still has 21% oxygen, there is less oxygen pressure in your lungs and blood. Your body tries to adjust to this lack of oxygen.

Your body's responses to high altitude include:

Making more red blood cells to carry more oxygen.
Changing how your blood carries oxygen so it can release it more easily.
Your kidneys help balance your blood chemistry.
Your blood vessels in your lungs might tighten, which can sometimes cause problems.

People who get altitude sickness often don't breathe faster enough. They might also have trouble exchanging gases in their lungs. Sometimes, fluid can build up in their body.

How Is Altitude Sickness Diagnosed?

Altitude sickness is usually diagnosed by how you feel. The symptoms are often clear: feeling sick, throwing up, and having a headache. These symptoms usually appear after a quick change in altitude. However, some symptoms can be confused with dehydration. In serious cases, doctors might use special scans like an MRI or CT scan. These scans check for unusual fluid buildup in the lungs or brain.

How Can You Prevent Altitude Sickness?

Going up slowly is the best way to avoid altitude sickness. Try to avoid hard activities like skiing or hiking during your first 24 hours at a high altitude. This can help reduce symptoms. It's also best to avoid alcohol and some medicines that can make it harder for your body to get used to the altitude. Alcohol can also make you dehydrated, which worsens altitude sickness.

Getting Your Body Ready (Pre-acclimatization)

Pre-acclimatization means getting your body used to less oxygen before you go to a high place. This can greatly lower your risk of getting sick. It also means you don't have to spend as much time at high altitude to get used to it. Some special tents, called altitude tents, can help. They create air with less oxygen, like at high altitude, while keeping the air pressure normal.

Getting Used to Altitude (Acclimatization)

Altitude acclimatization is when your body slowly adjusts to lower oxygen levels at higher elevations. This helps you avoid altitude sickness. Once you are above about 3,000 metres (10,000 ft) (about 9,800 feet), many climbers use a method called "climb-high, sleep-low." This means they stay at a base camp for a few days. Then, they climb to a higher camp (slowly) and return to the base camp to sleep. Later, they climb to the higher camp again and stay overnight. They repeat this process, spending more time at higher altitudes. This helps their body make more red blood cells to carry oxygen. Once they are used to that height, they repeat the process at even higher camps.

A good rule is to not sleep more than 300 m (1,000 ft) (about 1,000 feet) higher each day. For example, you could climb from 3,000 m (9,800 ft) to 4,500 m (15,000 ft) in one day. But then you should go back down to 3,300 m (10,800 ft) to sleep. You cannot rush this process safely. That's why climbers spend days or even weeks getting used to the altitude before trying to climb a very high peak.

Medicines That Can Help

The medicine acetazolamide (brand name Diamox) can help some people who go up quickly to sleep above 2,700 metres (9,000 ft) (about 8,900 feet). It can also help if you start taking it early when you first feel symptoms. You can take acetazolamide as a preventive measure before symptoms appear. The Everest Base Camp Medical Centre suggests taking 125 mg twice a day for prevention. Start 24 hours before going up and continue for a few days at the highest altitude or until you descend. For treating AMS, they recommend 250 mg twice a day. This medicine helps your body get used to the altitude faster. It makes your kidneys remove more bicarbonate, which helps you breathe more deeply and often. A minor side effect can be a tingling feeling in your hands and feet.

The CDC suggests that Dexamethasone should be used for treating severe AMS and HACE during descents. They also note that Nifedipine might help prevent HAPE.

There isn't enough proof to say if sumatriptan helps prevent altitude sickness. Also, popular antioxidant treatments have not been shown to work. Some medicines like sildenafil might even make headaches worse. A promising new medicine called myo-inositol trispyrophosphate (ITPP) could help hemoglobin release more oxygen.

Before altitude sickness starts, ibuprofen is a good painkiller. It can help with headaches and nausea.

Herbal Remedies and Traditional Medicines

Some people suggest herbal supplements and traditional medicines to prevent altitude sickness. These include ginkgo biloba, R crenulata, iron, and antacids. However, there isn't clear medical proof that these methods are effective or safe. For centuries, Indigenous peoples of the Americas, like the Aymaras in the Altiplano, have chewed coca leaves. They believe it helps with mild altitude sickness. But this has not been proven in scientific studies. In Chinese and Tibetan traditional medicine, an extract from Radix rhodiola is often used. Again, there are no clear medical studies to confirm its effectiveness or safety.

Adding More Oxygen

In high-altitude places, adding extra oxygen can help with the effects of low oxygen. Even a small amount of extra oxygen can make it feel like you are at a lower altitude. For example, at 3,400 metres (11,200 ft) (about 11,000 feet), increasing the oxygen level by 5% can make it feel like 3,000 metres (10,000 ft) (about 9,800 feet). This is much easier for people who are not used to high altitudes.

You can get oxygen from gas tanks or special machines called oxygen concentrators. These machines take oxygen from the air if electricity is available. Using extra oxygen increases the amount of oxygen you breathe in.

Other Helpful Tips

Drinking more water can also help your body get used to the altitude. You breathe faster in thin, dry air, so you lose more fluids. Just be careful not to drink too much water, as this can cause other problems.

How Is Altitude Sickness Treated?

The only sure way to treat severe AMS, HACE, and HAPE is to go down to a lower altitude right away. Symptoms will usually get better as you descend.

Trying to treat someone at high altitude can be risky unless there are good medical facilities. However, these treatments can be used if going down is not possible:

Oxygen: For mild to moderate AMS below 3,700 metres (12,000 ft) (about 12,000 feet), oxygen can be given. Symptoms often improve in 12 to 36 hours without needing to descend.
Gamow bag: For more serious cases, or if you can't go down quickly, a Gamow bag can be used. This is a portable, inflatable chamber that makes it feel like you are at a lower altitude. It's mainly used to help people get down safely, not to treat them at high altitude.
Acetazolamide: Taking 250 mg of acetazolamide twice a day helps treat AMS by speeding up acclimatization. Studies have shown it helps relieve symptoms and improves oxygen levels.
Traditional remedies: In countries like Ecuador, Peru, and Bolivia, people sometimes drink tea made from the coca plant (mate de coca) for altitude sickness.
Steroids: Medicines like steroids can help with the swelling in the lungs or brain. However, they don't fix the underlying altitude sickness itself.
Pain relievers: Studies have shown that ibuprofen (600 milligrams three times a day) can help reduce the severity of AMS. Paracetamol (acetaminophen) has also been found to be as effective as ibuprofen for altitude sickness.

Who Gets Altitude Sickness?

José de Acosta, a Spanish Jesuit from the 1500s, was one of the first to describe the problems of crossing the Andes mountains. He realized that the air was too thin for people. His observations helped us understand altitude sickness, sometimes called Acosta's disease.

Tourists and mountain climbers are two groups of people who often get altitude sickness. Your risk depends on your age, gender, how fit you are, your general health, where you normally live, your genes, and how fast you go up. People with certain health issues, especially those affecting the lungs, heart, or nervous system, are at a higher risk.

Mining at High Altitudes

Altitude sickness is a common problem for workers in mines high up in the Chilean Andes. These workers often live in lower areas but have to work at mines thousands of meters higher. Chilean law requires tests for employees working at high altitudes. If workers already at high altitude are found to be unfit, they are moved to lower elevations. They still keep their original salary.

Not much is known about the effects of going back and forth between low and high elevations. This is a common situation for workers in Chilean mines.