SafekipediaAltitude sickness
Adapted from Wikipedia · Adventurer experience
Altitude sickness is a problem that can happen when people go to very high places where there is less oxygen. When someone climbs quickly to a high altitude, their body may not have enough time to adjust. This can cause symptoms like headaches, tiredness, trouble sleeping, dizziness, and sometimes vomiting.
This kind of sickness usually happens above 2,500 metres, which is about 8,000 feet. But some people can feel it even at lower heights. Having had altitude sickness before, moving up very quickly, or being very active can increase the risk. Being in good physical shape does not protect someone from getting it.
To prevent altitude sickness, it is best to climb slowly, increasing elevation by no more than 300 metres (1,000 feet) each day. If symptoms appear, resting and drinking plenty of fluids can help. For mild cases, certain medicines may be used, and severe cases need immediate descent to lower altitudes. The only sure way to get better from serious altitude sickness is to go down until the symptoms go away.
Signs and symptoms
People can get altitude sickness when they climb very high mountains quickly. This happens because there is less oxygen in the air at high places. Some people might feel sick even at heights around 2,000 metres, like at ski resorts. Symptoms usually start showing up within ten hours of climbing and often get better in a couple of days. But sometimes, they can become more serious.
Common symptoms include headaches, feeling tired, stomach trouble, dizziness, and trouble sleeping. Moving around can make these feelings worse. Headaches are a main sign of altitude sickness, especially if they happen above 2,400 metres and come with other symptoms like feeling very tired or dizzy.
More serious symptoms can include feeling short of breath even when resting, coughing, and fever. There can also be swelling in the brain, which causes headaches that don’t go away, trouble walking, and confusion. These serious symptoms need quick help, like moving to a lower altitude, to get better.
| Disordered system | Symptoms |
|---|---|
| Gastrointestinal | Loss of appetite, nausea, vomiting, excessive flatulation |
| Nervous | Fatigue or weakness, headache with or without dizziness or lightheadedness, insomnia, "pins and needles" sensation |
| Locomotory | Peripheral edema (swelling of hands, feet, and face) |
| Respiratory | Nose bleeding, shortness of breath upon exertion |
| Cardiovascular | Persistent rapid pulse |
| Other | General malaise |
Cause
See also: Breathing § Breathing at altitude, and Effects of high altitude on humans
Altitude sickness can start when you climb up to about 1,500 metres (4,900 ft). The problem gets worse the higher you go, especially above 5,500 metres (18,000 ft), where you might need extra oxygen to stay safe.
When you climb high up, there is less air pressure and less oxygen. Even though the air still has oxygen, your body finds it harder to get enough. This can make you feel unwell. How fast you climb, how high you go, and how active you are all affect how likely you are to get altitude sickness.
Usually, if you climb slowly, your body can get used to the height, and the bad feelings will go away. But if you climb too fast to very high places, it can be very dangerous.
High altitude
At heights between 1,500 to 3,500 metres (4,900 to 11,500 ft), you might notice you get tired more quickly and need to breathe more. Your blood still carries enough oxygen, but you might feel the effects more.
Very high altitude
Between 3,500 to 5,500 metres (11,500 to 18,000 ft), getting enough oxygen gets much harder. This can cause serious problems, especially when you’re active or sleeping.
Extreme altitude
Above 5,500 metres (18,000 ft), there isn’t enough oxygen to keep your body working well. People can’t live permanently above this height. If you climb here too fast without extra oxygen, you could get very sick.
Mechanism
When you climb very high in the mountains, there is less oxygen in the air. This can make it hard for your body to get enough oxygen, which can cause problems. Your body tries to adjust by making more red blood cells to carry oxygen.
People can feel sick from this kind of air, with symptoms like headaches or feeling tired. It is important to take it easy when moving to high places.
| Type | At Sea Level | At 8400 m (The Balcony of Everest) | Formula |
|---|---|---|---|
| Pressure of oxygen in the alveolus | 21 % × ( 101.3 kPa − 6.3 kPa ) − ( 5.3 kPa 0.8 ) = 13.3 kPa O 2 {\textstyle 21\%\times (101.3{\text{ kPa}}-6.3{\text{ kPa}})-\left({\frac {5.3{\text{ kPa}}}{0.8}}\right)=13.3{\text{ kPa O}}_{2}} | 21 % × ( 36.3 kPa − 6.3 kPa ) − ( 1.8 kPa 0.74 ) = 3.9 kPa O 2 {\textstyle 21\%\times (36.3{\text{ kPa}}-6.3{\text{ kPa}})-\left({\frac {1.8{\text{ kPa}}}{0.74}}\right)=3.9{\text{ kPa O}}_{2}} | F I O 2 × ( P B − P H 2 O ) − ( P CO 2 RQ ) {\textstyle F_{I}{\text{O}}_{2}\times (P_{\text{B}}-P_{{\text{H}}_{2}{\text{O}}})-\left({\frac {P_{{\text{CO}}_{2}}}{\text{RQ}}}\right)} |
| Oxygen carriage in the blood | ( 0.98 × 1.34 × 14 g dL ) + ( 0.023 × 12 kPa ) = 17.3 mL O 2 100 mL blood {\textstyle \left(0.98\times 1.34\times 14{\frac {\text{g}}{\text{dL}}}\right)+(0.023\times 12{\text{ kPa}})={\frac {17.3{\text{ mL O}}_{2}}{100{\text{ mL blood}}}}} | ( 0.54 × 1.34 × 19.3 g dL ) + ( 0.023 × 3.3 kPa ) = 14.0 mL O 2 100 mL blood {\textstyle \left(0.54\times 1.34\times 19.3{\frac {\text{g}}{\text{dL}}}\right)+(0.023\times 3.3{\text{ kPa}})={\frac {14.0{\text{ mL O}}_{2}}{100{\text{ mL blood}}}}} | ( Sa O 2 × 1.34 mL g Hb × Hb ) + ( O 2 carriage in blood × Pa O 2 ) {\textstyle ({\text{Sa}}_{{\text{O}}_{2}}\times 1.34{\tfrac {\text{mL}}{\text{g Hb}}}\times {\text{Hb}})+({\text{O}}_{2}{\text{ carriage in blood}}\times {\text{Pa}}_{{\text{O}}_{2}})} |
Diagnosis
Altitude sickness is usually figured out by yourself because the signs are easy to see, like feeling sick to your stomach, throwing up, or having a headache. These signs often happen when you quickly climb a mountain or go to a place with less air. But, sometimes these signs can look like dehydration. In serious cases, a doctor might use special machines like an MRI or CT scan to check for extra fluid in the lungs or brain.
Prevention
Ascending slowly is the best way to avoid altitude sickness. Try not to do hard activities like skiing or hiking for the first 24 hours at a high altitude. Alcohol and sleeping pills slow down the body’s adjustment and should be avoided because alcohol can make symptoms worse. It is best not to drink alcohol for the first 24–48 hours at a higher altitude.
Pre-acclimatization is when the body gets used to low oxygen before going up high. This can lower risk because the body needs less time to adjust. Some people use altitude tents that copy high altitude by lowering oxygen but keeping air pressure the same. Other ways include ischaemic preconditioning, hypobaric air breathing, and positive end-expiratory pressure.
Altitude acclimatization is when the body gets used to lower oxygen at higher elevations. Above about 3,000 metres (10,000 ft), most climbers follow the “climb-high, sleep-low” method. They might stay a few days at a base camp, climb higher, and return. They repeat this, slowly spending more time higher up so the body can adjust. The rule is to climb no more than 300 m (1,000 ft) per day for sleep.
The drug acetazolamide (Diamox) can help some people who climb quickly above 2,700 metres (9,000 ft). It may also help if started early when symptoms begin. It is usually taken at 125 mg twice a day before symptoms start. The Everest Base Camp Medical Centre says it should not replace a slow climb plan, except in special cases. The Centers for Disease Control and Prevention (CDC) also suggest 125 mg every 12 hours for prevention. Acetazolamide works by changing the blood’s chemistry to help breathing. Side effects can include feeling tired and tingling in the hands and feet.
There is not enough proof to say if sumatriptan is safe or helpful for preventing altitude sickness. Antioxidant treatments have not been shown to work. Some think drugs like sildenafil might help, but they could make headaches worse. Another possibility is myo-inositol trispyrophosphate (ITPP), which may help release more oxygen.
Taking ibuprofen before altitude sickness starts can help with headaches and nausea. It has not been studied for preventing cerebral edema.
Herbal supplements and traditional medicines are sometimes used, like ginkgo biloba, minerals such as iron, antacids, and hormonal supplements such as medroxyprogesterone and erythropoietin. But there is little proof they work. Some Indigenous peoples of the Americas, like the Aymaras on the Altiplano, chew coca leaves to feel better, but studies have not shown this works. In Chinese and Tibetan medicine, Radix rhodiola root is used, but studies have not confirmed it works either.
In high places, adding oxygen can help with the lack of oxygen. A little extra oxygen can make a high place feel lower. For example, at 3,400 metres (11,200 ft), adding 5% more oxygen can make it feel like 3,000 metres (10,000 ft). Oxygen can come from gas bottles or special machines. These machines can make oxygen if there is electricity. Drinking more water helps the body adjust, but drinking too much can be dangerous.
Treatment
If someone has severe altitude sickness, the best way to get better is to go down to a lower altitude until they feel well again.
Doctors can help if going down right away is not possible. Giving oxygen can help with milder cases. A special bag called a Gamow bag can make it feel like the person is at a lower altitude. Some medicines, like acetazolamide, can help the body adjust faster. In some places, people use tea from the coca plant to help with symptoms. Steroids can help with serious symptoms but do not fix altitude sickness. Pain relievers like ibuprofen or paracetamol may also help.
Epidemiology
José de Acosta, SJ was a sixteenth-century Spanish missionary and naturalist in Latin America. His ideas about health problems when crossing the Andes helped us understand altitude sickness better.
Tourists and mountain climbers often get altitude sickness. Who gets it more depends on things like age, health, and how fast they climb. People with health issues, like anemia, are more likely to get it.
Altitude sickness is common for workers in mines in the Chilean Andes. Because these workers often live lower down and then work very high up, they can get sick. Chilean law requires tests to make sure workers can handle high altitudes and moves those who can't to lower places.
We still don’t know much about how working at high altitudes affects miners’ health.
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