Altitude Sickness

It's a bodily reaction to lower oxygen levels. Symptoms may worsen as the individual climbs higher and it can be very serious if not treated.

Altitude means any height over 1,500 metres above sea level, but sickness is most commonly experienced at heights above 2,500 metres. Heights over 3,600 metres may cause severe symptoms.

If you are travelling into these conditions you should explore the effects of altitude sickness and take steps to prevent it. Destinations that may cause altitude sickness include ski resorts, cycling holidays and trips to areas such as the Colorado Rockies.

Anyone can get altitude sickness; it depends on your body's reaction. You may not have developed symptoms on a previous trip, but this doesn't mean you won't in the future. Because it can be so serious it's worth taking precautions and paying attention to any symptoms experienced, even if it means you miss out on a planned outing or target.

Acute mountain sickness (AMS)

Although the name is 'acute' this is the mildest form. It can occur at heights over 2,500 metres above sea level. If you begin to feel unwell at this height, start taking steps to ensure your safety. AMS is a warning sign your body is affected by altitude. You may feel like you have a hangover or the beginning of flu.

High altitude pulmonary oedema (HAPO)

This is a build-up of fluid in the lungs that prevents enough oxygen intake. It can occur within hours and be fatal. HAPO can happen at heights over 2,500 metres, particularly if several days have been spent at altitude. The gradual restriction of oxygen is not fully understood, but it is a medical emergency and the individual should seek immediate attention.

High altitude cerebral oedema (HACO)

This condition is a build-up of fluid in the brain rather than the lungs. It can cause coma and death within a few hours. It is rare, affecting just a few people who ascent over 3,000 metres above sea level.

Both HAPO and HACO can follow on from mild symptoms of altitude sickness, so symptoms should never be ignored.

Mild altitude sickness causes symptoms similar to a hangover or flu. They include nausea, headaches, tiredness, loss of appetite, dizziness, lack of breath, racing heart and an upset stomach. You may feel worse at night.

These are all signs that the altitude is causing ill effects on your body. If you ignore these symptoms you may develop severe altitude sickness complications of HAPO or HACO. Symptoms of these life-threatening conditions are:

• As above but worsening
• A cough
• Bubbling chest
• Coughing up liquids
• Consistent breathless
• Clumsiness
• Double vision
• Fits and confusion

These are the life-threatening symptoms of a lack of oxygen and a build-up of dangerous fluids. Seek immediate medical attention.

Air pressure is lower at high altitudes. We are used to breathing the air found at sea levels, so when we move into high altitude areas our bodies can find it difficult to cope. Less oxygen can mean an increase in heart rate and breathing which can lead to other body changes in the blood and brain chemicals

Moving to lower heights decreases the symptoms. No matter how fit and healthy you are, altitude sickness could occur. It is not a sign of weakness or failure to try hard enough.

The best way to manage altitude sickness is by giving your body a chance to acclimatise to its new surroundings. It can take several days for your body to adjust, acclimatisation should not be rushed. Trying to speed up acclimatisation can mean you end up sick.

Avoid alcohol, smoking and drink lots of water. Don't undertake any hard physical exercise on your first day, and make sure you have a gentle start to your ascent.

If you can allow a night between every 500 metres rise when you're above 2,000 metres, and 300-500 metres once over 3,000 metres, above sea level you are at less risk. Ascending slowly and taking breaks when needed helps too.

Prevention is the best way to manage altitude sickness but if you find yourself becoming unwell you shouldn't go any higher until you feel better. If you experience symptoms, don't exercise, drink lots of water and rest. Avoid smoking and make sure companions are aware you feel unwell so they can look out for worsening symptoms that could lead to HACO and HAPO.

If you don't feel better after two days begin a descent by at least 500 metres. After a few days at that height, you can try again as acclimatisation may have taken place. If you don't feel better or get worse you should descend immediately and seek medical help.

Preventing altitude sickness

Taking it slowly and acclimatising is the best way to prevent altitude sickness. Some medications have also proven useful too.

Herbal remedies

There are many herbal remedies for altitude sickness available, but there is no clinical evidence they work. Don't rely on herbal remedies to treat altitude sickness. If you feel unwell descend and rest.

Prescription treatments

There are some medications clinically proven to prevent acute altitude sickness in adults. They work by correcting a blood imbalance caused by the lack of oxygen.

Prescription medicines should be taken before, during and after an ascent to work properly. If you are planning a trip to high altitude and think you may experience sickness, or you've had altitude sickness in the past, it can be worth taking this type of medication. It's prescription only, so you will need to speak to your doctor.

Altitude medication is prescription only because it is not suitable for everyone and may cause side effects of nausea, numbness, and tingling.

If you are allergic to the ingredients or have liver or kidney disease it may not be suitable. Don't take altitude medication belonging to anyone else. It needs to be prescribed to fit with your health and current medications.

It is much easier to prevent altitude sickness than treat it; prevention ensures everyone is safe, happy and able to enjoy the trip. It's worth putting in extra days and effort to ensure the trip is successful. No-one is to blame for altitude sickness; it can happen to anyone and be very serious.

Other tips for preventing altitude sickness include:

• Keeping a close eye on your health and the health of your travelling companions
• Resting or descending whenever it's necessary, remember severe altitude sickness can be fatal.
• Take rest days if ascending at speed so everyone can acclimatise
• Hydrate yourself with water - no caffeine - alcohol or fizzy drinks
• Eat high calorie foods
• Don't smoke or use any medication unless it is prescribed for you and you have spoken to your doctor about its use at altitude
• Look out for other problems of altitude such as the increased risk of sunburn. This can happen in snowy conditions too, so always use sunscreen, and wear a hat, sunglasses or goggles.

Looking out for the signs of altitude sickness can save ill health and even prevent death. Make sure everyone in your group is acclimatised and ready to move on before making decisions.

If you have symptoms, stay at the current height for up to two days, if you worsen or don't get better then start descending. It may be disappointing but it's not worth endangering your life.

If you are prescribed altitude sickness medication take it regularly as prescribed and seek medical attention if you feel unwell.

Altitude sickness is easy to overlook in the excitement of preparing for a trip abroad, but if you're planning a skiing, cycling, hiking or climbing trip remember to look at the altitudes and consider whether you may experience altitude sickness. Usually trips to the Alps, for example, do not cause problems, but it's worth being prepared.

In advance you should ensure that medical insurance covers altitude sickness, and arrange medication if needed. Once on the trip keep a close eye on your health and if you experience symptoms stop ascending and acclimatise. If you don't feel better or get worse you should descend and seek medical help.