Air travel and your health

Every year approximately 2,000 British travellers return home with malaria and the UK is one of the biggest importers of malaria among industrialised countries.

The most severe form of malaria (Plasmodium falciparum) is on the increase amongst British travellers and in 2006 approximately 80% of travellers returning to the UK with malaria had this most deadly form. An average of nine British travellers die each year from malaria, which is a preventable disease.

A simple approach to malaria prevention is called the ABCD :

A: Awareness of risk
B: Bite reduction
C: Commence preventative medication before travel
D: Diagnose and treat promptly if prevention fails

It is essential that you visit your GP, Practice Nurse or Travel Clinic to discuss your precise travel plans as the drugs used for prevention vary depending upon the area visited. When the appropriate drugs are taken, these are between 90 and 100% effective when used in conjunction with the advice above.

Should you feel unwell on return from a malarious area, it is essential that you seek urgent medical advice and give full details of the areas that you have visited on your travels to the health care professional.

Further information may be found at:

• NHS - Fit For Travel

If you have a medical condition that is stable, e.g. a stroke which has left residual weakness which impairs movement and no further complications, you do not need a medical certificate.

If you have an unstable condition, e.g. an underlying heart condition which had led to the stroke and is ongoing, a note from the treating physician outlining the medical condition will help with the decision on fitness to fly.

It is important to consider what insurance you need before booking flights and holidays. If you are travelling outside the UK you should always take out travel insurance to cover the costs of medical care if you are injured or become unwell while you are away, including the costs of getting home.

Sometimes travel insurance is provided with a bank account or credit card. Make sure that you read the policy conditions (including the 'small print') to make sure that you have the right cover to meet your needs. Most policies require you to make an annual declaration of your health in order for you to be properly insured.

Declare your medical history

You must almost always tell your insurer about existing medical conditions to be covered for them. You must also disclose any changes to your health during the policy term. If the insurer does not ask you about any pre-existing conditions that you have, the condition is almost certainly not covered by the policy.

Medical treatment in Europe and the European Health Insurance Card

The UK Global Health Insurance Card (GHIC) lets you get necessary state healthcare in the European Economic Area (EEA), and some other countries, on the same basis as a resident of that country. This may be free or it may require a payment equivalent to that which a local resident would pay. The UK GHIC has replaced the existing European Health Insurance Card (EHIC). If you have an existing EHIC you can continue to use it until the expiry date on the card. Once it expires, you'll need to apply for a UK GHIC to replace it. If you have rights under the Withdrawal Agreement, you can choose to apply for a new UK EHIC rather than a UK GHIC, though neither are a replacement for travel insurance.

Similar health agreements exist in other countries, (for example Australia), as well as some British Crown dependencies such as the Channel Islands and the Isle of Man.

If you are travelling abroad, you may need vaccinations when visiting certain countries.

You should make an appointment with your GP or Practice Nurse and advise them of your trip in order that an appropriate vaccination schedule may be carried out in a timely manner.

It is important that you give specific details of the areas that you are visiting, along with the time of year that you are planning to travel and the duration of your trip.

Passengers with a blood count of greater than 8 may travel without problems assuming there are no other conditions such as heart or lung disease. If the count is less than 7.5 special assessment should be made and consideration to the use of supplemental oxygen should be considered. If the anaemia is chronic, passengers often tolerate a slightly lower blood count without problems in flight, but in this case it is essential that the airline is informed of precise medical information via the MEDIF Form.

The treatment for a broken arm or leg usually includes a plaster or fibreglass/resin cast to immobilise the broken bone. Checks are made when the cast is first put on to make sure that it isn't too tight and doesn't stop the circulation to the tissues. However, problems can still occur if the tissues around the fracture swell after the cast has been applied, either as a result of the injury itself or due to blood pooling in the immobilised limb.

Because of the risk that swelling inside a cast can affect the circulation, many airlines restrict flying during the first 24 or 48 hours after a cast has been fitted. If you need to fly before then, the airline will usually require the cast to be split along its full length before you fly, as any swelling will not then affect the circulation. This can be arranged at the hospital. You may also have to make arrangements to have the cast replaced once you reach your destination. It is helpful to carry a letter confirming the date and time of application of the cast, especially if you have not had the cast split.

If you have a broken arm or leg, you will not be allowed to sit in an emergency exit row. Also, if you have a broken leg and are unable to bend your knee to sit normally, you may be required to purchase additional seats so that you have enough space. This will also allow you to elevate the leg during flight and will reduce any swelling that would occur if you kept the leg down.

Pneumatic Splint

A pneumatic splint is a plastic sleeve or sock which can be inflated with air to form a rigid splint. They are often used by first aiders to immobilise a suspected fractured limb. However, they are not suitable for use when flying, as the pressure within the splint is affected by the changes in air pressure in the aircraft.

Should I discuss my trip with my diabetes team?

Air travel should not pose significant problems for travellers with well-controlled diabetes. Pre-planning is important and discussion of the travel itinerary, four to six weeks in advance, with your GP or treating specialist team plays an important part in preparation for travel.

What should I pack?

Passengers may carry essential liquid medicines such as insulin for the period of their trip. These are permitted in larger quantities above the 100ml limit for liquids, but will be subject to authentication.

All prescription medication and dietary liquids that you have medical confirmation for are allowed. Any that are in containers of 100 ml or less may be placed in a re-sealable plastic bag as above if you wish. This can be carried in addition to a bag containing toiletry and cosmetic items and must be presented separately to cabin baggage. Any containers over 100 ml must also be taken out of cabin baggage, and will be subject to additional screening.

The security officer may ask to see your medical confirmation. This could be your name on a prescription label or a letter from your doctor. You should only carry the amount you need for your trip.

For diabetic passengers who use insulin pumps and/or continuous glucose monitoring (CGM) devices, it is essential that they speak to the airline to obtain precise advice on the use of such devices on board the aircraft.

Passengers must also take with them supporting documentation from a relevant qualified medical professional.

It is essential that diabetic passengers carry adequate equipment (glucose meters, lancets, batteries) and medication in their hand baggage. It is also important that insulin not being used in the flight is not packed in the hold baggage as this may be exposed to temperatures, which could degrade the insulin, in addition there is also the potential that luggage may be lost en-route.

It is useful to have simple carbohydrates to treat hypoglycaemia including glucose tablets or sweets. It may also be useful to pack longer lasting carbohydrates such as snack bars or biscuits in case of delayed meals.

What should I do on-board?

• Frequent blood glucose monitoring is essential.
• Avoid excess caffeine and alcohol as these can affect diabetes control including your warning of hypoglycaemia.
• If you are travelling North or South there is no need to change the timing of your insulin or other medications.
• Similarly keep to your regular regimen if you are crossing fewer than 5 time zones.
  • Travelling West means that your day will be longer - you may need more insulin;
  • Travelling East means that your day will be shorter - you may need less insulin.

As noted above, it is best to discuss this with your diabetes team in advance. If you use oral medicine, it may be easier to skip one dose rather than take two doses close together. A short period of slightly high glucose levels will not cause harm.

Insulin pumps

There have been some concerns about possible effects of airport security screening equipment on insulin pumps. Guidance from the Department for Transport is that both insulin pumps and CGMs must not be either screened by x-ray or pass through the security scanner.

At airport security passengers with insulin pumps can opt for an alternative screening method. You will need to carry a letter from your doctor confirming your situation which should be handed to the security officer. This applies to all EU airports which should be aware of the requirement

The CAA and the Airport Operators Association (AOA) have produced a Medical Device Awareness Card for passengers with an insulin pump or CGM that can assist passengers in preparing for their journey, and provide the correct documentation at the search area. The card also acts as a reminder to security officers that alternative processes to screening by security scanner and spare devices by x-ray are available.

The Awareness card can be downloaded here.

Changes in the cabin air pressure can have an effect on insulin delivery. The reduction in cabin air pressure when the aircraft climbs may lead to a slight increase in delivery of insulin as a result of the formation or expansion of air bubbles in the insulin syringe or tubing. This might be sufficient to cause symptoms of hypoglycaemia. A more severe impact could be seen in the (very rare) event of sudden decompression of the cabin at altitude. A slight reduction in insulin delivery is also possible during descent. You should discuss the best way to manage this with your doctor.

At my destination

Should you run out of insulin and need to source this locally, remember the strength may be different as many countries still use U-40 or U-80 as opposed to the U-100 used in the UK.

Some safety advice for illness

• Always continue taking your insulin, even if you're not eating.
• Test for ketones if your blood glucose levels are above 14mmol/L
• Positive ketone tests always require treatment with extra insulin
• If you are unable to eat because you are ill, you can obtain carbohydrate from sources such as high-energy drinks (e.g. Lucozade), fizzy soft drinks, squashes and milky drinks.

The fear of flying is the third most common phobia after the fear of snakes and spiders. Whilst 90% of adults are apprehensive when flying, fear only occurs in 10-25% of airline passengers.

There are various components which may cause the fear of flying - concern over heights, loss of control, claustrophobia, physiological effects, media "hype" and fear of the unknown.

To help overcome the fear, some airlines run courses which combine behavioural techniques and educational input on aspects of flying, including helpful material on aircraft noises and other area which may cause distress, such as turbulence. Many courses finish with a flight, which is carried out in carefully controlled situations.

Research has shown that the above interventions are effective and that the benefit may be sustained.

In severe cases, a GP may be able to prescribe a mild tranquiliser to assist in the process.

During the flight, it is advisable to avoid excess caffeine and alcohol.

In 2010 the British Cardiovascular Society published guidelines on air travel for patients who have a heart condition. The report concludes that the vast majority of people who have a stable heart condition can travel safely, although some will require some special assistance, for example in getting around the airport or in having additional oxygen supplied during the flight. However, some people who have more severe heart disease or whose condition is unstable, may have to delay travelling until their condition has improved.

If you are planning a flight, it is a good idea to check with your GP or hospital specialist before you book your flight. You should make sure that you have adequate travel medical insurance if you are going abroad, even if you are only going to Europe and already have an EHIC card.

If your doctor is not sure if you are fit to fly, contact the airline you intend to fly with for advice. Most airlines have a special assistance or medical clearance team and there will be information on how to contact them on their website. You must contact the airline before your flight if you will require help at the airport, wish to carry additional medical equipment or will need extra oxygen during the flight. Sometimes the airline will need additional medical information and will ask your doctor to fill in a medical information form (MEDIF) before they will confirm whether you are fit to fly.

Remember to carry your medication with you in your hand-baggage, in case you need to use it during the flight. It is also a good idea to take a copy of your repeat prescription, in case you need to get more medication when you are away from home.

The list below gives general guidance for some common heart conditions, but each case does have to be looked at individually and some airlines may apply different rules.

Angina

Angina is not usually a problem in flight, provided that your symptoms are stable and controlled by your medication. If you sometimes get chest pain on gentle exercise, such as climbing a flight of stairs or walking up a slight slope, you will still probably be able to fly but might need assistance at the airport and to have extra oxygen during the flight. However, if you sometimes get chest pain when you are at rest you may not be able to travel by air.

Heart attack (myocardial infarction)

If you have had a heart attack, you may be able to travel after 7 to 10 days, provided that there have not been any complications. If the blocked artery that caused the heart attack has been successfully unblocked, it may be possible for you to fly after as little as 2 to 3 days.

Heart failure

Heart failure occurs when the heart is weakened and is no longer able to pump blood around the body as effectively as it should. Most people who have heart failure are still able to fly, provided that the condition is stable and well-controlled on treatment. However, if you get breathless on gentle exercise you may need to request assistance at the airport and to have extra oxygen during the flight. However, if you sometimes become breathless when you are at rest or when you lie down, you may not be able to travel by air.

Pacemakers and implantable cardioverter defibrillators (ICD)

Travelling by air should not be a problem if you have been fitted with a pacemaker or an ICD. The modern devices are designed so that they will not be affected by any of the security screening equipment at airports and will not cause any problems with the aircraft electronic systems. However, they may set off the airport security alarm and therefore you should carry a letter from your doctor to explain that you have been fitted with the equipment and, if possible, show this to the security staff before you go through the security arch.

Heart surgery

Patients are often discharged from hospital very quickly these days, even after major surgery such as coronary artery bypass grafting or replacement of a heart valve. Normally you should not fly after such surgery for at least 10 days and until you are able to manage normal daily activities. You may need to request assistance at the airport if you still need help with baggage or are not yet able to walk the sometimes long distances from check-in to the aircraft.

Hypertension (high blood pressure)

Your blood pressure should not be affected by air travel and therefore there is no reason why you should not fly if you are being treated for high blood pressure. However, your travel insurance may not cover the cost of any additional treatment or complications, so it is advisable to only travel once your blood pressure has been controlled and your treatment is stable.

You can find more useful information on the British Heart Foundation website.

Your doctor might also wish to consult the British Cardiovascular Society website

The key focus when considering the pregnant traveller is the health and wellbeing of the mother and the baby.

Delivery in flight, or diversion in flight to a location, which may not have high quality obstetric services, is undesirable and for this reason, most airlines do not allow travel after 36 weeks for a single pregnancy and after 32 weeks for multiple pregnancies.

Most airlines require a certificate after 28 weeks, confirming that the pregnancy is progressing normally, that there are no complications and the expected date of delivery.

The majority of individuals with conditions such as asthma and chronic obstructive pulmonary disease, sometimes called COPD, can travel perfectly safely on board an aircraft. It is essential however to carry all relevant medications, such as an inhaler, in cabin baggage. Contrary to popular belief, modern aircraft are not pressurised to sea level equivalent and fly with a cabin altitude of between 5,000 and 8,000 feet, causing a slight reduction in oxygen. This should not cause symptoms in the majority of individuals with mild / moderate disease. It is important that you discuss your intention to travel with your treating physician who knows all your medical details, in order that an accurate assessment can be made. In general terms, if a passenger can walk 50 yards/metres at normal pace, or climb one flight of stairs without significant breathlessness, oxygen should not be required.

If it is felt that supplementary oxygen is required, it is important that the airline is notified well in advance with a MEDIF Form in order that this service can be provided. Some carriers do make a charge for this. Recent work has shown that the majority of those with lung conditions respond well to supplementary oxygen in flight and should be able to travel worldwide.

The ultimate decision to carry a passenger is that of the airline and the more information the airline has, the better and more objective that decision can be. Information can be provided to the airline either by telephone and your treating physician can give details via the MEDIF Form.

The subject of air travel following a surgical operation is becoming an important issue with the increasing frequency of day surgery. The time between surgery and travel varies depending on the complexity and extent of the surgical procedure.

It is appropriate to allow one to two days following keyhole surgery and between four and five days for simple abdominal surgery. Major chest or abdominal surgery requires a period of approximately ten days. Simple cataract or corneal laser surgery do not cause major complications and therefore 24 hours is an adequate gap between surgery and flying. More complex eye surgery, for example that used for a detachment of the back of the eye (retina) require approximately one week before air travel.

It is always best, in more complex cases, to contact the airline concerned in order that their medical adviser can have as much information as possible before making a decision on fitness to fly.

Most people with mobility problems have found it possible to travel by air, especially with legislation which was passed in 2008. If there are other medical issues you should check with your GP that these are taken into account.

If the conditions are complex, the use of the MEDIF Form may be required.

Useful guidance for travellers is given on the following links:

• See our Assisted travel pages for more
• Department for Transport Code of Practice
• Directgov - Advice regarding airport and airline services for disabled travellers

A wide range of medical devices worn on or in the body are now available for many healthcare needs. Some are for monitoring purposes, some administer medication and others take the place of bodily functions. Some examples are these are Continuous Glucose Monitoring systems (CGMs), insulin pumps, stoma bags, cochlear implants and feeding tubes.

Prosthetic devices are replacement body parts widely used in modern medical treatment. They may be fitted internally or externally and include replacement lenses in the eye following cataract surgery, artificial heart valves, hip replacements and breast implants. External prostheses include those used in cosmetic surgery or following breast cancer treatment, and artificial limbs.

Both internal and external devices that are partly or completely made of metal are likely to be detected by walk through metal detectors or security scanners. Other external devices, such as external breast prostheses, insulin pumps and stomas, may also be detected by security scanners. Security staff may carry out an additional hand-search if you are wearing an external prosthesis or medical device. This may be carried out in a private room by a security staff member of the same sex as you. You can also ask for a friend or family member travelling with you to be in the room while the search is carried out if you wish.

It is helpful to carry a letter from your doctor confirming that you have been fitted with a medical device or prosthesis, and whether this is fitted internally or is an external device. This should be shown to the security staff, if possible before you go through screening.

Additional useful information for diabetic passengers wearing insulin pumps or CGMs is available from Diabetes.Org.uk, and for those who have had breast implants or wear an external breast prosthesis from the breast cancer charity at: Breast Cancer Care

The manufacturers of medical equipment usually have patient support services available online via the internet or by telephone and they should be able to give advice on any potential problems that can be caused by airport security screening.

It is also helpful to carry a letter from your doctor confirming that you have been fitted with medical equipment, whether this is fitted internally or carried on the outside of the body, and whether you are carrying spare medical equipment in cabin baggage. This should be shown to the security staff, if possible, before you go through screening.

Internally fitted medical devices

Devices made of or containing metal, such as hip replacements may set off an alarm on walk through metal detectors but will not be affected or damaged by them. They may also be seen on security scanners, but again will not be affected or damaged.

Externally fitted medical devices

As there have been some concerns about possible effects of airport security screening equipment on insulin pumps and Continuous Glucose Monitoring systems (CGMs), updated guidance from the Department for Transport is that both insulin pumps and CGMs must not be either screened by x-ray or pass through the security scanner, so will be screened by alternative methods.

If you do not wish to be screened by security scanner you can ask for a hand-search. This may be an enhanced hand-search in private to ensure equivalence with a security scanner. Security staff can exercise discretion as to the extent of the search, subject to the security officer being able to reasonably satisfy themselves that no prohibited article is present.

The security officer must explain to the individual to be screened how they are required to present themselves for screening by security scanner. Any alarms will be subject to, at least, a 'targeted search' of the area of the body that has alarmed; it may be necessary for a hand-search in private to be carried out.

You should not be asked to remove your medical device for screening.

If you are carrying a spare medical device remove it from your cabin bag before the X-ray and let the Security Officer know. If you have any concerns or queries before you travel contact the airport and do note that screening equipment and processes may differ from airport to airport.

The CAA and the Airport Operators Association (AOA) have produced a Medical Device Awareness Card for passengers with an insulin pump or CGM that can act as a reminder to passengers to prepare for their journey, and provide the correct documentation at the search area. The card also acts as a reminder to security officers that alternative processes to screening by security scanner and spare devices by x-ray are available.

The Awareness card can be downloaded here.

Security scanners are used to show items that may be hidden under clothing and have been approved for use at airports in the UK and many other countries.

There are strict rules to protect your privacy; therefore an effective privacy policy must be put in place by the airport operator to protect individuals when being screened by security scanners. This must include the installation and use of Automatic Threat Recognition (ATR) software. ATR software interprets the scan data, instead of creating an image, and identifies areas where items may be concealed on the body. These areas are flagged on a standardised stick-figure on a screen, to indicate to the security officer areas of the individual's body which should receive a targeted hand-search.

You may have read articles in the press about being exposed to radiation in the security scanners and be particularly concerned if you fly frequently. All security scanners must use millimetre wave technology, as it poses no known health and safety risks. Millimetre wave scanners utilise a very low power, non-ionising form of electromagnetic technology. Non-ionising radiation refers to electromagnetic waves which do not alter atoms in molecules by removing electrons. The amount of electromagnetic radiation emitted by millimetre wave security scanners is many times lower than that emitted by a mobile phone.

Before this technology was introduced, its safety was checked by the Health Protection Agency (HPA).

At airports where security scanners are used, you can ask for an alternative method of screening if you are unwilling to be scanned. This may be an enhanced hand- search in private to ensure equivalence with a security scanner. Security staff can exercise discretion as to the extent of the search, subject to the security officer being able to reasonably satisfy themselves that no prohibited article is present. This could be more intrusive than a hand-search you may have previously experienced or seen when a passenger has alarmed the walk through metal detector - for example, you may be taken to a private room or cubicle and be asked to remove or loosen items of clothing. Should an enhanced hand-search in private be required, you may have a companion with you if you wish and the search will be carried out by a security staff member of the same sex as you, along with a witness to the search.

Most people understand the need for high levels of security at airports and on board aircraft. Methods used to screen passengers and their baggage range from visual inspections and a hand-search to the use of several types of screening equipment. Some people worry that their health may be affected by the equipment used in security checks.

Most people will be used to walking through an archway after having taken all metal items - coins, mobile phones and so on - out of their pockets. These arches are walk through metal detectors and will also detect metal inside the body, such as artificial joints and heart pacemakers.

If the equipment alarm goes off, a security guard will usually carry out a hand-search. It may be helpful to carry a letter from your doctor if you have had a joint replacement or pacemaker which can set off the alarm. You may also be asked to be screened by a security scanner.

Modern commercial aircraft fly at altitudes where the atmosphere outside the aircraft is not able to support human life. All aircraft therefore have systems which ensure that cabin air provides adequate oxygen levels for breathing, as well as removing contaminants and maintaining a comfortable temperature.

On the majority of large commercial aircraft the cabin air supply is provided by using some of the outside air which has been drawn into and compressed in the engines before being bled off before combustion occurs. This causes it to heat up rapidly compared to the outside air. This so-called ‘bleed air’, which has very low levels of moisture (humidity), passes through air-conditioning units before being distributed throughout the cabin. The system is automatically controlled to maintain the cabin air pressure at a safe level.

Up to half the cabin air is re-circulated and passes through air filters, similar to those used in hospital operating theatres, to remove bacteria, viruses and other particles before it is mixed with outside air from the air-conditioning units. Re-circulation helps to increase the moisture level in the cabin air and, because of the use of the high efficiency filters, does not lead to an increased risk of infection.

In recent years some people have expressed concerns about possible health effects due to exposure to contamination of cabin air, particularly contamination of the air drawn from the engines by engine oil.

In 2007, the Department for Transport asked the independent Committee on Toxicity (COT) to conduct a review of the evidence. They concluded that the evidence available did not establish a link between cabin air contamination and ill health but made some recommendations for further research.

In 2013, following the publication of additional Government funded research, the Committee reviewed the topic again and a produced a position statement. The Committee members thought it unlikely that the long-term illnesses that have been reported are linked to a toxic effect of cabin air contamination.

In 2022, the committee was asked by the Department for Transport if any new data has been published since the last report, to re-evaluate whether the views expressed in the position statement remained correct based upon the best available peer-reviewed data.

Reassuringly, the Committee reached the conclusion in their 2024 updated position statement that the levels of the chemical contaminants reviewed in the aircraft cabin air are unlikely to cause adverse health effects following acute or long-term exposures.

You can read the full statements and position papers from the COT on its website.

Our statement on fume events

We recognise that there is a strong public interest in fume events, particularly those that relate to engine ‘bleed air’. Based on the available data submitted through our Mandatory Occurrence Reporting process, occurrences relating to engine bleed air are rare, forming only a very small proportion of the total number of fume event reports we receive each year.

It is acknowledged that people who experience a fume event (of any type) may report symptoms such as irritation to the eyes, nose and throat. These symptoms usually resolve once the fumes or smell have disappeared. Long term ill health due to any toxic effect from cabin air is understood to be very unlikely, although such a link cannot be ruled out.

Our priority is always the safety of passengers and crew, and we continue to work with airlines, manufacturers and international regulators to drive improvements in safety standards across the industry.

We will continue to monitor developments and remain receptive to any new peer-reviewed published research or technological innovation.

One of the symptoms often described after flying is dry eyes, this is due to the dry atmosphere on board the aircraft. The relative humidity in most air-conditioned buildings is between 40 and 70 per cent, which is ideal for comfort. On an aircraft, the relative humidity may be of the order of 20 per cent. High water content lenses may dry and distort more than those with lesser water content. This problem may be overcome with gas permeable lenses. Drinking excessive amounts of tea, coffee and alcohol can exacerbate dryness.

Contact lens wearers may have to dampen their lenses and should remove them prior to sleeping during the flight.

Passengers may carry small quantities of liquids, each of which must have a capacity not greater than 100 ml, this includes contact lens solution. You can carry a contact lens case containing fresh lens solution in order that you may remove your lenses should you experience discomfort on the flight, so it is essential that you carry your spectacles in your hand luggage. Although it is perfectly safe to store spare lenses in hold luggage it is not advisable lest the luggage does not appear at your destination.

I have been diagnosed as having an infection which is contagious (an infection that may be passed from one person to another). I am due to fly soon, what should I do?

You should delay your flight until the illness is no longer contagious. Talk to the doctor who is treating you to find out when you will be able to travel.

If possible, arrange to get a letter from the doctor once you are no longer contagious, confirming this and that you are fit to fly. This can be particularly important for some illnesses, such as chicken pox, where you may still have some signs of the illness such as a spots or a rash. The airline may refuse to let you travel if the staff at the airport or on the aircraft think that you may still be contagious.

It is advisable to inform the airline that you are due to fly with, as they will be able to tell you if they have any specific requirements such as a letter from your doctor before they will let you travel. They will also tell you if there will be any additional charges if you have to change your booking. You should also contact your insurer if you have travel insurance, as you may be able to make a claim if you have to pay to re-book your flight or have to cancel the flight or a holiday because of your illness.

Should I fly if I have recently been in contact with a person who has a contagious disease (an infection that may be passed from one person to another)?

You should talk to your doctor and let them know that you are intending to fly. The doctor will be able to tell you how likely it is that you will develop the illness, how long it usually takes for someone to become unwell if they do catch the infection and what you should do if you develop symptoms.

For most infections you are only likely to be contagious (able to pass on the disease) once you have symptoms of the illness. If you are feeling well and do not have any signs of illness, such as a rash or a cough, you will probably be able to travel.

Don't forget to check that you have travel insurance cover, in case you become unwell and need medical treatment while you are away.

Why do I always pick up an infection after I have travelled in an aircraft?

Most contagious illnesses, such as chicken pox, measles, 'flu or the common cold, are spread as a result of close contact between people. This most commonly happens through 'droplet spread' - breathing in viral particles or bacteria carried into the air when someone with the illness coughs or sneezes close by.

You might pick up an infection on the aircraft if someone in a seat close to you has a cold or other contagious disease. However, it is just as likely that you could catch an infection from someone close to you when travelling by public transport, at the airport, in your hotel or at a conference - indeed anywhere where you might be in close contact with other people.

You may have heard that you are more likely to catch an infection on board an aircraft because some of the cabin air is re-circulated. However, the air that is re-circulated passes through filters which are highly effective at removing particles, including bacteria, viruses and fungi that can cause infection. Research has shown that you are no more likely to catch an infection on an aircraft that has re-circulated air than on one where the air is not re-circulated.

A blood clot or DVT, as it is known, can occur in individuals with specific risk factors at any time.

The risk factors for DVT include age greater than 40, previous DVT or blood clot in the lung (pulmonary embolism) or a history of such conditions within the family.

Other factors that are found to be important are hormonal changes associated with pregnancy, the use of the oral contraceptive pill and hormone replacement therapy. Recent surgery or trauma and many forms of cancer can also be associated with increased clotting of the blood.

In addition to these factors, there are some inherited abnormalities of the blood clotting system which may pre-dispose individuals to DVT and pulmonary embolism.

Research by WHO has been published on DVT, which confirms that immobility is an extremely important factor and that being seated for more than four hours in a car, bus, train or an aircraft may increase the risk of blood clotting.

Simple measures may reduce the risk of blood clotting; these include increasing mobility by walking around the aircraft cabin and carrying out simple lower leg exercises that are illustrated in many in-flight magazines.

Drinking adequate amounts of non-alcoholic beverages is important on a long flight, but the routine use of aspirin has not been shown to reduce the risk of clotting which takes place in the veins of the leg. In addition, there is a potential hazard with aspirin and the balance between benefit and harm is not in favour of aspirin and thus its routine use cannot be recommended. However, individuals who may have any of the risk factors outlined should seek medical advice, and it may be that in certain circumstances compression stockings or therapy directed at preventing the clotting process may be appropriate.

If you are unfortunate enough to suffer a DVT associated with travel, the journey home should not be a problem. It is important that any "blood thinning" treatment is stable before travel in order that maximum protection is afforded. It is worth letting the airline know and your treating physician can give details via the MEDIF form.

Why do some airlines carry cardiac defibrillators on their aircraft?

Cardiac arrest is one of the most common causes of sudden death. It is caused by an abnormal heart rhythm which rapidly stops the heart pumping blood round the body. This usually happens during a heart attack, but can also occur with a number of other heart conditions. If a normal heart rhythm cannot be restored in a few minutes, the person will die. It may be possible to keep the person alive by giving them life support (CPR - cardiopulmonary resuscitation), but usually a normal heart rhythm can only be restored by using a heart 'defibrillator'.

The heart muscle has to contract in a regular and coordinated way to pump blood around the body. 'Ventricular fibrillation' is the most common cause of a cardiac arrest and it leads to the heart muscle beating in a completely irregular and uncoordinated way. A defibrillator causes an electrical shock to be passed through the body, which will often change a fibrillating heart to a normally beating one.

The cardiac defibrillators that are carried on aircraft, and are sometimes seen in other public places such as train stations, shopping centres and sports grounds, are known as 'automated external defibrillators' or 'AEDs'. They are very simple to use and once attached to a person are able to automatically detect the heart rhythm and decide if a shock is needed. They are also very safe to use, as they will only allow a shock to be given if it is necessary. Non-medical people can be trained to use them as part of a first aid or life support training course.

Why isn't it compulsory for airlines to carry a defibrillator on an aircraft?

All airlines are legally required to train their cabin crew in first aid and to carry first aid kits on their aircraft. Some airlines have chosen to carry AEDs and to train their cabin crew to use them. However, there is no legal requirement for them to carry defibrillators and some people have suggested that the regulations should be changed to make this compulsory.

Cases of sudden cardiac arrest are very rare when compared to the number of passengers. The evidence from those airlines that have been carrying defibrillators is that although a few lives are saved, in most cases the use of a defibrillator is not successful. This is partly because some of the cases are not due to ventricular fibrillation and a defibrillator will not be able to restore a normal rhythm. Also, even if a normal heart rhythm can be restored, the cause of the abnormal rhythm - such as a heart attack - cannot be treated until the person gets to hospital and this can take several hours.

Although defibrillators are now more commonly found in public places, they are not a legal requirement even in places where large numbers of people gather. There is no evidence that airline passengers are at increased risk of sudden cardiac arrest and most authorities do not consider that it would be justified to make it compulsory for all aircraft to carry defibrillators.

The process of disinfection is required under the International Health Regulations of the World Health Organization (WHO) on flights to and from certain destinations to prevent infectious and contagious diseases. These rules permit the use of insecticides, which are recommended by the WHO based on their effectiveness and safety.

Further information may be found on the World Health Organization website.

It is not unusual for your skin, lips and eyes to feel drier after a commercial flight. The air on board an aircraft has about 20% humidity, versus approximately 40 – 60% in an office on the ground. There is also a possibility that the disruption to the body’s internal clock from crossing time zones (known as jetlag) may also partially contribute to this sensation.

Whilst this may feel uncomfortable, it is important to state however that there is no risk of dehydration from this.

The overall fluid loss from an 8-hour flight is equivalent to only an additional 150mls of water, or a small cup. For those curious, the calculation of this from first principles (including assumptions) is below:

• Assumed aircraft cabin pressure of 8000ft (2440m) is 565 mmHg (75.3kPa), ambient temperature of 21°C and 20% relative humidity.
• Passengers estimated to have a ventilatory rate of 15 breaths per minute and tidal volume of 500 mL per breath.
• The inspired air humidity is 20% of the saturated water vapour pressure at 21°C of 18.7mmHg. This is 0.2 x 18.7mmHg or 3.74mmHg.
• This is then heated to a body temperature of 37°C and fully saturated within the upper respiratory tract. This exerts a water vapour pressure of 47 mmHg.
• Using the formula Absolute Humidity (g/M³) = (216.7 * water vapour pressure in mmHg)/(temperature + 273.15), the values of water per mg/L in alveolar air is 44mg/L, and within inspired air 2.75mg/L.
• The water therefore added by the body to each litre of inspired air is 41.25mg/L.
• A breathing rate of 15 breaths of 500mls air over 1 hour is 15 * 0.5L * 60 or 450L per hour of air. Over an 8-hour period altitude, this would be 3600L.
• 41.25mg/L * 3600L = 148 500mg water. Converted to grams and therefore also millilitres = 148.5mls water. 

There are some simple steps you can take to make your flight more comfortable. This includes applying skin moisturiser and lubricating eye drops, as well as removing contact lenses before sleeping on board.

Modern aircraft cabins are pressurised to between 5,000 and 8,000 feet, which causes gas within our body cavities to expand. The body contains air in the middle ear and in the sinuses. As the aircraft climbs, the air expands in the middle ear and flows to the outside via a connection called the Eustachian tube. The air in the sinuses escapes via the nose. On descending, the reverse occurs via the same connections. To assist in this flow of air and avoid pain in the ear or sinuses, it is helpful to periodically swallow, chew or yawn during the descent. Babies often cry, and this has the same effect.

In order that these mechanisms work efficiently, it is not advisable to fly with an infection of the ear, nose or sinuses, as the swelling, which occurs with this infection, can prevent free flow of air and result in pain, bleeding or in the most severe cases, a ruptured ear drum.

Most contagious illnesses, such as chicken pox, measles, 'flu or the common cold, are spread as a result of close contact between people. This most commonly happens through 'droplet spread' - breathing in viral particles or bacteria carried into the air when someone with the illness coughs or sneezes close by.

You might pick up an infection on the aircraft if someone in a seat close to you has a cold or other contagious disease. However, it is just as likely that you could catch an infection from someone close to you when travelling by public transport, at the airport, in your hotel or at a conference - indeed anywhere where you might be in close contact with other people.

You may have heard that you are more likely to catch an infection on board an aircraft because some of the cabin air is re-circulated. However, the air that is re-circulated passes through filters which are highly effective at removing particles, including bacteria, viruses and fungi that can cause infection. Research has shown that you are no more likely to catch an infection on an aircraft that has re-circulated air than on one where the air is not re-circulated.

Passengers with severe allergies can feel vulnerable when flying due to the theoretical risk of accidental exposure whilst on board. The CAA has commissioned two reports on the topic to better understand the risk of this occurring. The first was from the Health Safety Laboratory (HSL) in 2018. 

A subsequent literature review from Imperial College was then carried out to update this work, as well as to consider ways to prevent it from occurring if necessary. The report covers evidence base for risks and best management of food-allergic individuals on commercial airliners: a systematic review. 

A summary of this work follows:

• The rate of medical events onboard an aircraft is lower than in the non-aviation environment. This may be because of precautions taken by those who travel, such as bringing their own food or notifying the airline in advance of their condition.
• There is evidence to support passengers with allergies wiping down their seat area, tray table and seat-back entertainment system. Some airlines offer pre-boarding to passengers with severe allergies time to allow them the chance to do this.
• When a passenger eats peanuts onboard, the amount that enters the air around them has been shown to be too small to trigger allergic reactions in those nearby.
• Those at risk of anaphylaxis should always carry an adrenaline autoinjector and a spare in their hand luggage. A doctor’s letter is not required to bring these onboard, nor is permission required from your airline. Government guidance is available.
• You should always review your airline’s website in advance of travel to ensure you are aware of their policy relating to food allergies. You may also be able to request alternative catering where this is served onboard.
• Airlines should consider stocking a separate supply of clearly identifiable “general use” adrenaline autoinjectors on-board their aircraft in case of an episode of anaphylaxis.

The CAA accepts the findings of this report in full and encourages UK airlines to consider how they may incorporate the findings into their operations where relevant.

Separately, a review of anonymised safety reports (MORs) related to allergies onboard UK-registered aircraft over the last 5 years has also been undertaken. The findings from this work have been published online in the Journal of Travel Medicine.

Jet lag is a problem that is directly related to our 'body clock'. Almost every function in the body is influenced by a 'master' body clock which is located within the brain and sets our 'circadian rhythms'. These allow our body to predict changes in the environment and help to synchronize sleep and activity over a 24-hour period.

The most important factor in setting our body clock is the cycle of light and darkness. However, our body clock does not cope well with rapid and large changes in the timing of environmental signals like light, which is what happens when we fly quickly across world time zones.

'Jet-lag' is the term used for the symptoms you may feel while your body clock adjusts to time in the new location. Symptoms of jet-lag include feeling tired during the day in the new time zone, and yet experiencing disturbed sleep at night, feeling less able to concentrate or to motivate yourself, decreased mental and physical performance, increased incidence of headaches and irritability, loss of appetite and gastro-intestinal problems such as constipation.

Any journey, particularly if more than 3 hours, can cause discomfort and tiredness whether you are travelling by car, bus, train or aeroplane. You may spend long periods in a cramped position and there may be other stresses such as delays, unplanned stops or detours. These symptoms do not last long and often improve after a rest, some light exercise, or a shower or bath. You will usually experience symptoms of travel fatigue after any long-haul flight, but you will only suffer from jet-lag if you cross several (probably more than 3) time zones. You only cross time zones if you travel eastward or westward, so you won't suffer from jet lag if you fly more or less directly north or south, for example from the UK to Africa or from North to South America.

The severity of jet-lag depends on the number of time-zones you cross and, to a lesser extent, on the direction of travel. For most people, the symptoms are worse if they travel eastwards than if they travel westwards. The symptoms may also depend on whether you are a morning-type "lark" or an evening-type "owl". There is little evidence that jet-lag symptoms are different between men and women, or between older and younger people.

The symptoms of jet lag will naturally get better as the body adjusts to the new time zone. However, recovery may take 1-1.5 days per time zone crossed and there are a number of ways in which you can try to speed the process up.

You can start the process of adjustment before you even leave home by changing the time at which you go to bed and get up. If your journey is eastward, for example from the UK to India, you could move your body clock forward by going to bed and getting up an hour earlier. Similarly, if you are travelling westward, for example from the UK to Canada, you could move your body clock backwards by going to bed and getting up an hour later. You should not attempt to re-set your body clock by more than 2 hours before you travel.

If you have a choice of different flight schedules and arrival times, a late afternoon or early evening arrival might be better, since you can "use" the tiredness due to travel fatigue to help you get a full night's sleep in the new time-zone.

Many travellers find it helpful to set their watches to the time zone at their destination as soon as the flight begins. Depending on the time of your flight, you should try to get some sleep during what would be night-time at your destination. The timing of meals is another cue that helps readjustment of the body clock, but most people have little choice in the timing of meals on the flight. Although the timing of meals can help to synchronise human circadian rhythms, there is little evidence that the content of meals, such as a diet higher in protein or carbohydrate content, speeds up adjustment to the new time zone.

If you are only travelling to a new time zone for a short period (less than 48-72 hours), it may be better to try and avoid adapting to the new time zone by staying on your home time. You should try to make sure that you eat and sleep at your normal times - if you are having difficulty getting as much sleep as you need, try to have a nap in the early afternoon after lunch, when you will naturally be sleepy. If you are travelling on business, try to arrange any important meetings for times when you will be more alert - during the local morning if you have travelled westwards or the local afternoon or early evening if you have travelled to the east.

The most commonly used 'medication' is caffeine in the form of caffeinated drinks, such as coffee. Other drinks such as tea or cola usually have lower levels of caffeine and there are also other energising drinks which may have much higher levels. Caffeine will help to combat any daytime sleepiness, allowing you to stay awake until the local night-time. However, it is important that you avoid caffeine in the evening, or you may then find it difficult to get off to sleep when you go to bed.

Sleeping pills help to reduce jet lag symptoms by improving sleep, particularly if you are trying to get to sleep at a time when you would normally be awake and alert at home. Some sleeping pills can also cause daytime sleepiness and should not be taken if you plan to undertake activities such as driving, flying, scuba diving or skiing where this could be dangerous. They should be prescribed by your doctor, not be taken with alcohol and only used for a few days at a time. It is also better not to use sleeping pills during the flight as sleeping in one position in your seat for a long period might increase your risk of deep vein thrombosis (DVT).

Many people find that they fall asleep more quickly after alcohol. Unfortunately alcohol has been shown to reduce the quality of sleep and so this is not a good way of combating the effects of jet lag.

Melatonin is produced naturally in the body and is important in regulating our body clock. It is often recommended as an effective treatment for jet lag but in many countries melatonin is not available 'over the counter' and has to be prescribed by a doctor. It can also be difficult to be sure of the amount and purity of melatonin bought in health food outlets or on the Internet.

A large number of studies have been undertaken to find out whether melatonin can reduce jet lag symptoms and many have shown that it can be beneficial. However, it is not clear whether these effects are simply due to it acting like a sleeping pill or whether it does help the body clock to adjust to a new time zone more quickly. The effects of melatonin medication are also affected by the body's natural cycle of melatonin production and it may be important to adjust the time the medication is taken depending on the direction and number of time zones crossed.

In many countries, including the UK, pilots and cabin crew are not allowed to use melatonin when they are on duty (which includes the days off when they are overseas) because of the unpredictability of its effects on alertness.

The most important factor in setting our body clock is the cycle of light and darkness. Not surprisingly, exposure to (or avoidance of) light is an important factor in how quickly you adjust to a new time zone.

Exposure to daylight has the most effect, but the best time to be outdoors if you are trying to combat jet lag depends on your direction of travel and the number of time zones you have crossed.

The table shows recommended times for avoiding or seeking exposure to daylight.