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Frequently Asked
Travel Health Questions

Animal Attacks | Fit to travel | Index | Infections | Kids |
| Malaria | Off Beat | Vaccinations | Tips


Jules Eden, travel medicine specialist and founder of e-med, answers travellers' questions - as published in the following national publications

  • The Guardian
  • Independent On Sunday and/or
  • Geographical Magazine

Q. I took a flight from the U.S.A. in April of this year...it was a 24 hour flight and my face was so red and my body swollen for like a week after I arrived in Malaysia. I will be returning home in October and I do not want the same thing to happen. I have moderately high blood pressure, which I am taking a low dose of atenolol for (25mg). I drank plenty of water on the flight and avoided alcohol and soda yet this didn't seem to help. Does the actual act of flying increase the blood pressure and what do you suggest I do to prevent this problem?

A. The problem with the swelling is not due to blood pressure, but it is oedema. This is where fluid leaks into the tissues due to inactivity in flight. It is most common to get it in the legs, not the face and upper body.

To decrease it next time, drink a little less fluid and make sure your seat is upright as possible. However it might be worth trying a different sort of blood pressure tablet. A diuretic like bendrofluazide helps lower blood pressure by getting rid of excess fluid. Perhaps switch meds a few days before the flight back.

In flight there is a slight drop in oxygen levels, but it is so small that it should not make your heart have to work any harder to get all the tissues correctly fed. Likewise the inactivity puts less demand on the body so all should be fine where blood pressure is concerned. However stress can increase it, and as any frequent flyer knows, there are plenty of stresses for passengers. So relax for the return flight, it should be fine if you try my tips.

Q. I've recently found that prolonged flights trigger sciatic pain, which doesn't go away for weeks afterwards. Can anything be done to prevent this, or to relieve the pain more quickly afterwards? I'll be taking long-haul flights next year, so I'm quite concerned.

A. It sounds that your lower spinal position in-flight is pinching the sciatic nerve roots. I suggest you learn some exercises to use during the flight from a physio. It's also best to get up every hour or so and flex and extend your lower back. Simple toe touching will do to loosen you up.

Q. I am currently recovering from varicose vein surgery on my left leg (I am 29). Several veins were removed from my leg and I have been advised to wear the prescribed compression stocking for a further week (the operation took place on Feb. 18th) I plan to fly to Paris at the beginning of April and would like to know a) if it will be safe to fly by then and b) if I should take any precautions e.g. wear a compression stocking during the flight.

A. No need to worry.Varicose veins are part of the superficial venous system and as such have no real role to play in the formation of the dreaded DVT’s. 6 weeks after the operation things should be back to normal with no residual inflammation or soreness in your lower legs.

The compression stockings are used post op to prevent swelling and aid blood return in your leg which now has less veins. This will be through the deeper leg veins.

So it’s OK to fly and for the short trip to Paris, it would be a shame to arrive in the fashion capital of the world in Spring, looking like you are dressed for Winter.

Q. My 14 year old son is in remission with Acute Lymphoblastic Leukaemia and has a Hickman line in situ for his maintenance treatment. We are going to Disneyland Paris in a few weeks (by air). Should we tell the airline and are there any possible problems? Thanks

A. There is no real need to tell them this. A Hickman line is an intravenous line place into one of the veins of the neck and goes down towards the heart. This is done so that shots of chemotherapy can be given regularly without needing to place a line in the vein each time.

It does not contain any air as after each dose it should be flushed through with normal saline/ heparin mix to stop it from clotting up. So there are no worries regarding air expansion on take off.

The only thing to watch for is on descent. When he has to equalize to pop his ears this can raise the pressure in the thorax and there may be a bit of flush back down the line. Make sure the cap on the line is tightly fitted to stop blood from oozing o

Q. I occasionally get really bad throbbing localised pain in my forehead as the plane starts its decent. It is often only one the one side of my forehead although sometimes I have had it on both sides. The strange thing is that it only happens on some flights. At other times I have no pain what so ever. Is this a sinus problem or is it an indicator of something more serious?

A. No need to worry, this is nothing more serious than a “sinal squeeze”. You have 3 sets of sinuses, and the biggest are in the forehead. These are called the frontal sinuses. When a plane descends, despite it being “pressurised” there is an increase in relative pressure, like when you dive underwater. So the air in the sinuses needs to be equalized by blowing more in up the nose. If you cant do this for whatever reason, then a small vacuum begins and begins to cause the sinal lining to swell up. Hence the pain.

If you are getting this regularly then it would be worth using a nasal decongestant about 2 hours before you land. Either a tablet called Sudafed, or a spray like Otrivine work well. If this fails then a trip to an ENT surgeon may be needed.

Q. I am writing to you beacuse I get very nervous when I fly. I have been on three flights in my whole life and everytime I fly I get this feeling of impending doom. Is there anything I can take to calm me down during the flight? Could there be a psychological disorder associated with fear of air travel? Please help.....

A. There is a psychological problem associated with flying, probably called aerophobia, however people suffer it in different ways.

It becomes a problem if it results in you not actually flying, but it seems you can get on the plane. A “feeling of doom” may be just mild symptoms so I think you can be easily cured.

Do not resort to drugs at this stage but look to go on one of those courses where you are put into a flight simulator with a psychologist. After 9/11 there has been a great demand for this treatment and there should be plenty of them in L.A.

They will look at what gives you these feelings and resolve them.

Q. I wonder if you could help with a problem regarding long haul travel. My husband is in remission from Non-Hodgkin's Lymphoma and has been clear for 5 years. The lesion was in the soft pallet in his mouth. He underwent aggressive chemotherapy and then radiotherapy to the mouth and nasal areas. The chemotherapy has resulted in peripheral nerve damage to both legs and feet and although it has improved, he has stabilised to numbness in the feet and lack of circulation to both legs.

The radiotherapy has damaged the facial sinus tissue and on short haul flights he always gets an infection in the sinus area. He is on steroid spray daily and regularly washes the nasal area and throat with saline solution in an effort to combat infection. We intend visiting Australia and New Zealand next year for a family wedding. Is there any significant risk as regards DVT and what can be done to reduce the risk of catching anything through the re-circulated air?

Would it help if we travelled on business class rather than economy or would that not make any difference? I would be grateful for any advice as this is a concern as to whether the trip may cause further damage and any risk of picking up a major infection. Many thanks in anticipation for any assistance.

A. If he has damage to the blood circulation of his legs then he has to pull out all the stops to avoid a DVT on the light.

So business class would be better, as there is more leg room and so less flexion at the knee, which classically slows the blood return and causes the clot.

He should use graded pressure stockings and take 150mg of aspirin.

Drink at least 4 –5 litres of water on the flight and take a regular hourly walk up the aisles.

Stopping infection will be hard. He needs to prevent the drying up of the nasal mucous. This acts as a barrier against in flight bugs. A mask as used against SARS can help.

If an infection does get hold though, have some amoxicillin handy to hit it hard and quick.

Q. I have heard about the sad death of the young girl after the long haul flight from Australia, what exactly caused this and how can I prevent it happening to me when I fly there next month?

A. What happened to this girl was sadly preventable and also becoming more frequent as flights get longer and seats get more cramped.

She suffered a blood clot in the deep venous system of her calf. This is called a deep venous thrombosis or DVT. If part of this clot dislodges, it travels up the venous system back to the heart, through the right side of the heart and to the lungs. This is what happens to cause death , as if a big enough piece of the clot gets to the lungs then it causes the blockage of the blood supply there. This is called a pulmonary embolus and it can be fatal.

Recent research has shown that up to 1 in 4 people that get a DVT have all been in a long haul flight in the last few weeks. You can see that this is an incredible statistic as a lot of the smaller DVTs go undiagnosed as they don't cause the classic symptoms of swelling of the calf with redness and pain in the same area.

The reason that air travel can cause this problem is due to several factors, all which seem to coexist on these flights.

Firstly for a clot to form the blood needs to be very slow moving. This occurs inflight as passengers sit in a cramped position with their knees bent. This can restrict the flow back of the blood and help a clot form. The next problem is with dehydration. It is said that you should drink a litre of fluid every 3 hours on a flight, but what is normally given out, ie alcohol can actually dehydrate you more as it makes you need to urinate more often. As you now have less circulating fluid volume the chances of clot formation are a lot higher.

Finally the swelling in your lower legs due to the position you sit in also causes to constrict the veins too. So these factors can cause a clot, but also being on the contraceptive pill, obesity and smoking too will all increase the risk.

What is recommended to stay alright inflight is to keep your toes moving by regularly going for a walk up and down the aisle, and also keeping well hydrated.

I would also suggest that anyone who is high risk, and by that I mean overweight, OCP taking smokers who have a family history of clots forming, take a dose of 75mg of aspirin before they fly, as this thins the blood enough to stop the DVT forming. However if you suffer from stomach ulceration or allergy to aspirin then there is a shot of a blood thinning agent called heparin available.

If anyone experiences tender calf swelling or chest pain and shortness of breath after a flight, then please seek medical attention immediately.

Q. Help, please!  On the two long-haul overnight flights I've taken, I have fainted (and fitted apparently). I used to faint fairly regularly as a child but would estimate I now do it only every couple of years.  Also, I'm taking tablets for high blood pressure.  I do not drink alcohol when flying, I wear flight socks and drink water.

This happens when I awake after falling asleep - and I would find it
impossible to stay awake!  If I carry on doing this, am I likely to do
myself any lasting or long -term damage?  What, if any, risks are
involved? Should I stop these overnight flights?  Do you have any other suggestions? -  I was so looking forward to seeing the rest of the world!

A. It is odd that you only fit after waking on an aeroplane and not anywhere else.

Fitting is quite a serious symptom, with dangers of inhaling vomit causing respiratory spasm. So I think your best option is to make sure there is no underlying disease that has caused this. You need to see a neurologist who will try to exclude any of the forms of epilepsy, and maybe even do an MRI scan of your brain as well.

If a cause is found, treatment will control the problem. But if all is clear, and it's just one of those things, then look closely at your blood pressure. If you are sitting upright and taking tablets then it may be too
low after sleep, hence the faints.

A solution could be to fly in a class where you could sleep horizontally, or even look to decrease your meds the day before flight.

Always warn the person next to you what may happen, it can be equally frightening for them too if it were to happen again.

Q. I am a flight attendant and have been diagnosed with chronic fungal sinusitis and need to know if I am making it worse by flying or not. I have talked to all sorts of experts and found conflicting answers. I have had 5 surgeries to remove polyps with more developing every day. I have had surgeries to clean out a massive infection of pseudomonus that keeps occuring and nothing they give me will fight the fungal infection. Can you help me?

A. You have to be clear here that you do actually have a fungal sinal
infection. This is very rare, and could more likely be the bacterial
pseudomonas coming back. To manage this it is best to get a sample and send it to a microbiology lab for culture and antibiotic sensitivities. Generally ciprofloxacin works well, but would have to be taken for a good while to get active in the sinuses.

However if it is fungal, and that has been proven again by sampling, you
should be given the correct antifungal, as a tablet and even a nasal spray. If the nose spray does not exist then use antifungal ear drops as they can be sniffed up to your sinus with practise.

Flying should not really worsen this problem, as the pressure differences on ascent and descent are not huge. You may have to pop your sinuses on landing as the pressure increases, but this shouldn't make an infection worse, though it may be painful if your sinuses are a bit blocked with infection. Use Sudafed tablets to help open up the sinuses so air gets in better.

Finally polyps can keep infection in, so make sure the ENT doctors keep on top of these.

Q. My employer ruptured his eardrum last weekend and is scheduled for a flight this coming Saturday for business - can he fly with a ruptured eardrum?

A. He can fly with this problem. Because the drum has a hole in it, the air that expands as the plane goes up freely moves out of the middle ear through the new hole.

Likewise on descent, air will be pulled in through the perforation so
equalizing the ear.

After a drum rupture, it can take any length of time to heal, depending on how big the rupture is and any superseding infection. From a week to many months. To prevent infection, he must keep it dry. So no swimming or diving. And when in the shower a wax plug is useful to prevent water from dripping in.

Q. My mother has an abdominal aortic aneurysm [AAA]. She lives in the States, but would like to fly here (to England) to see me, about an 8 hour flight. She asked one doctor about flying and the answer was 'no way', a second opinion was yes. She is still very unsure, could you please help. She is 63 and has had knee replacement also.

A. The aorta is the main arterial blood vessel that runs through the body. From the heart down to the pelvis, this major source of blood supply to the lower body is vital for life. If due to weakness in it's walls it becomes distorted and balloons to a larger size, it is called an aneurysm. The risk of this is that it can burst or have the walls dissect along its length. This then results in a dramatic loss of blood out of the system into the abdomen, or the cutting off of blood to tributaries that run to other organs like the kidneys.

This is a disaster medically, even if she were sitting in an A&E. It would
result in a 4 hour operation to replace the affected vessel, so imagine the problems if this were to happen in flight.

But, people with AAA, do fly for a couple of reasons. Firstly because it is only a minor problem with a minimally distorted size, and secondly because the problem has not been diagnosed yet. Often the only way people find out they have an AAA, is when it bursts.

So your mother needs to find out exactly what the chances of this are
happening. If her vascular surgeon feels that there is less than a 1-2 %
chance of it blowing then I think that is reasonably low enough to take the flight. Being on a flight wont necessarily increase the chances of it going off, it's just the remoteness of an operating theatre.

If however she is on a waiting list to have it fixed and her surgeon feels
there is over a 2% chance of problems then do not fly, or even get a boat, just wait for the op and fly 8-10 weeks after that.

A. I am flying to Australia in December when I will be  5 1/2 months pregnant. What risks to the baby are there? The one I am most  concerned about is the radiation dose and the effects it may have.

Q. Don't worry. I agree there is a slight increase in radiation when you fly as you are higher up in the air and so not covered by many thousand of feet of atmospheric protection. But this is only minimal. As your child is also deep in your womb too this also helps.

There are areas of the UK like Cornwall where radon can give far more
background radiation that a flight and I am sure you wouldn't think twice about going there.

As for other issues. You are allowed onto a long haul flight at 51/2 months as it is way of any chance of premature labour.

Just keep well hydrated and enjoy an Australian Christmas.

Q. Is it safe to fly if you have high blood pressure? My father just recently was kept overnight in the hospital because he lost feeling in his left arm due to a high blood pressure episode. He is travelling from Mexico to Miami this week, is there anything he should be aware of?

A. It is essential that your father only flys if his blood pressure is under control.

It sounds like he had a TIA or transient ischaemic attack. Here a small part of a clotted artery gets loose and can end up temporarily blocking a vessel in the brain. Hence the symptoms.

There is a risk this can happen again if his BP is not under control. The effects of this can be worsened by the relative lack of oxygen in the plane. The chance of a DVT could be higher if he has poor vessels too, so I think the best option is for him to take aspirin daily before flying, and to get a local doctor to check his blood pressure a few days before travel. If it is still above 160/100 forget the flight and start on an anti-hypertensive.

Q. I'm a student pilot in Australia and have just started having some dental work done. The Doc is also giving me Amoxicillin as we go, because I have an artificial hip and apparently infection can cause a problem here. How does this affect my flying? I only had to take 3mg's after today's dental visit mixed in water and don't have to take any more now until the day before each of the coming dental visits in tablet form. The dental visit's are about a month apart. Does this mean I can't fly now until the dentist visits are ALL over or does it just need a day or two after each dose?If you can help here, it would be much appreciated

A. I cannot see why taking amoxicillin should affect your ability to fly, whether as a passenger or pilot.

If you have bad teeth problems, then there are rare circumstances where air trapped in a cavity expands on ascent. If this can get out then it is very painful, but a good dentist shouldn't leave you in this state.

Amoxicillin is a simple antibiotic, there are no side effects that would hinder you at the controls. As you haven't had an allergic reaction after the earlier doses then you are free to fly.

Q. If my experience is anything to go by, your correspondent is right to worry about whether Amoxillin might affect his ability to fly. Although I had never previously had any adverse reaction to antibiotics, I vomited for fourteen hours almost non-stop when I was given the drug by a dentist following treatment. My GPs comment was that Amoxillin was one of the older, more troublesome drugs many doctors no longer prescribed, though dentists seemed to be fond of it. I would certainly not like to be a passenger in a plane whose pilot has just had a dose of Amoxillin!

A. The nature of allergy is that on the first instance there may be a mild reaction like swelling, itching and redness. The next time it can be fatal. Anaphylaxis occurs, due to a massive release of histamine from certain cells in the body. You get respiratory failure due to constriction in the lungs and death from shock. That's the bad news. The good news is that this is unlikely to happen with amoxicillin. Firstly your pilot would not be taking it a second time if there was a problem before. Secondly, I have faith that there must be rules governing the use of medication and flying. It would be odd to be prescribed a treatment and then take it just as you were about to pilot a plane. Anaphylactic reactions happen very soon after the medication is taken, so if there was a consult on the day of the flight, your pilot wouldn't even manage to flick the "On" switch. So rest assured, unless of course wasps are nesting in the cockpit!

Q. I have a 56 year old friend who is planning a short break to Madrid very shortly. A couple of years ago he suffered two minor strokes and is now taking medication to control his blood pressure, ie Enalapril, doxazosin, amlodipine, pravastatin, dipyridamole, and aspirin. Is it safe for him to fly while taking this cocktail of drugs?

A. That is quite a collection of medications he is on. The first 3 are to control the blood pressure, the last two to thin the blood, and the pravastatin is to lower the cholesterol level.

The situation as regards flying is that his blood pressure must be well in control on the meds. If it is above 160/100 there is a risk that another stroke can occur. In his situation I recommend he buys his own blood pressure monitoring device. They cost less than £50 and are probably more accurate than the situation at the doctors where the BP rises rapidly in the waiting room.

The fact that he is on 3 different antihypertensives means that control of the BP is proving difficult, so get the pressure checked before flight.

It is a good idea too to get insurance above and beyond the E111 form so the best care can be obtained whilst away.

Q. I have a perforated eardrum and on descent experience excrutiating pain in my ear from increase in air pressure. I have tried using an earplug, sucking a sweet, swallowing repeatedly and yawning, all to no effect. The pain is so bad that I have started to dread flying. Is there anything I can do to prevent or alleviate the pain ?

A. This sounds a bit odd. If you have a hole in your eardrum, then as the plane descends air will contract in the middle ear, and air should be drawn into this space through the hole you have.

So either the hole has closed, or there may be a one way valve like situation stopping air from being sucked in.

You need to see your doctor again to check the current state of the eardrum. If the hole is still there then never ever use an earplug as this will worsen the situation.

Try using a tablet called Sudafed that dilates the Eustachian tube and allows air to pass more easily into the middle ear space.

Finally, if this really ruins flights, and there are no contraindications, then a grommet can be inserted. This is a plastic pipe put across the drum that allows air to vent easily in and out of the middle ear. This though needs an ENT referral, which can take some time.

Q. I am due to have a caesarian section on the 10th of September, and hope to fly from Birmingham to Belfast on the 20th of September, returning on the 22nd. Is there any reason why either myself or the new baby should not make the trip, or will it be safe for us both? The flight lasts for 50 minutes.

A. Normally after an operation that involves cutting through the abdominal wall it is advisable to rest for a couple of weeks.

Your flight in only 10 days after the op, and often you are kept in the Maternity Ward for 7 after a Caesarian.

So you could be looking at hospital discharge and 3 days later boarding for the flight.

I think this is too soon for you. There is no reason your child can not fly but I think too much could go wrong for you at this early stage.

So delay the flight for a couple more weeks at least.

Q. Do you have any tips for avoiding jetlag?

It ruined the first week of my last trip to Bali, and I don't think I can face the tiredness again.

A. "Go west" sang Neil Tennant, probably because he had experienced enough jet lag for a lifetime.

Most travellers realise that west is best to avoid this most modern of
travellers afflictions.

Jetlag is simple really. Every 15 degrees of latitude is 1 hour. Fly to and
from the USA and you gain or lose 5 hours. Add this to the real time of
flight and up to 13 hours can be the difference.

But when you fly west and gain time it is easier to cope with this
difference. Simply stay up as late as possible, hit the sack and set your
alarm for local time in the morning and you will be fine in a day.

Going East is harder, as with fitful sleep on a plane, you can lose a night's kip, leaving you shattered on arrival.

So here's my tip. On departure, set your watch for local arrival time.

Think what you should be doing if that were the time of day at home.

Would you be asleep or active?

Active is easy, sit in your seat and wiggle your toes. Asleep is harder, if
you can, do, but we know the incessant interruptions you get in flight. If
not take a short acting sleeping tablet that kicks in quickly with no
hangover effects. Zopiclone or zolpidem work well, give you 6 hours
straight, and the only downside is a metallic taste in the mouth. You can sloosh this away though with one of those little juices they give you all the time.

Dehydration can worsen jetlag, so keep a steady input of fluids when not asleep. A litre every couple of hours should do it and it will help stave off Economy Class DVT's as well.

Q. I will be flying this Saturday and I have been taking Amitriptyline for a number of years for chronic headaches. I am terrified of flying , my doctor has prescribed Diazepam 2 mg. I have stopped taking Amitriptyline on Wednesday night , to make sure I have not got too many drugs in my system, what will Diazepam do, and is it advisable to take.

A. Diazepam, or Valium as it is commonly known, is a benzodiazepine that decreases anxiety. It does not cause sleep like its cousin temazepam. It simply reduces the sensation of fear and trepidation with side effects of making you drowsy. Depending on exactly how terrified you are of flying it can be a good or bad drug. If you are mildly anxious, enough to sweat and feel your heart rate increasing then 2 mg will be appropriate, but if your fear is so bad you leave nail marks up the aisle as you are "shown" your seat, then you may need a stronger dose or even try Xanax, which can be better in acute anxiety.

There are issues of dependence with any benzodiazepine, so do not make a habit of using them too often. If this is a concern then a beta blocker called propranolol can be good. It should never be used by an asthmatic due to its side effect of bronchoconstriction. 40mg is the best dose.

There's no real need to stop the amitriptyline in your case, as the diazepam will only be a one off each way with flying.

Q. I know that jet lag is helped by not drinking coffee and tea. Does this apply to decaffeinated types? How long before a flight should one stop drinking them?

I thank you for your time.

A. The key to jet lag avoidance is to get your own body clock tuned in to your arrival time as soon as possible. If you are flying East, for example, and arriving in the morning then it is essential that you sleep on the flight. The problem with caffeine is two fold. Firstly it will keep you awake on the flight. Your sleep pattern will be upset and you may make the lag worse. Secondly it will dehydrate you in-flight and so make you feel more hung over on arrival.

Of course all things on moderation and one cup of coffee may not ruin everything. But taken just before you need to sleep, it could.

So set your watch for your destination and think "would I be having this at home at the same time?"

Yes. go for the 2 shot espresso, no.have a Horlicks.

Q. This may sound really silly, but I entered a competition and managed to win a holiday to Barbados, the first prize.

But you know how these things are, and not thinking I had a chance I entered for a bit of fun.

The problem is, is that since September the 11th I am petrified of flying. My husband is really looking forward to the trip but I would rather sit on a pointy spike than get on a plane again.

Is there anything I can do as I wish I had never won it now?

A. A dilemma that many of us wish we had, and at risk of sounding flippant you could give it to me!

Seriously, though, post September 11th there has been a dramatic rise in the cases of "fear of flying"

There are effective long term cures for this problem but they can take a while. The main ones are by psychological re-training. You go and sit in a flight simulator and learn deep breathing exercises. I know of a company near Heathrow that charge about £100 to get you over your fears.

However if you are looking for a quick temporary fix there are medications you can take to calm you down.

In the past I have known people to take the beta blocker "propranolol". This stops your heart from racing and keeps you calm in the wait before the flight.

Others have used diazepam. You can take a 2mg dose to take the edge off your fear, or try 5mg for more sedation according to how you are really going to be on the flight.

For a complete cocktail take 40mg propranolol 6 hours before take off, then the diazepam as you wait at the boarding gate. Both drugs are only on prescription and your doctor will warn you of any possible contraindications. Finally try relaxation tapes in-flight and just think of the warm beaches.

Good luck.

Q. My daughter who is 28 has fainted on the last two occasions when travelling long haul. She has been revived with oxygen by cabin crew. She is travelling, in December, to South Africa with British Airways and will be travelling alone. I am becoming increasingly concerned about this tendency to faint. Can you recommend any procedure that can be followed to minimise the risk of fainting and also why does this problem occur?

A. I think your daughter needs a trip to her GP before she flies again. When a plane cruises at high altitude there is a lower cabin pressure. Even though this is increased to a pressure well above the outside air at that height, it is never the same as at sea level. Because of this the oxygen concentration is lower. In most passengers this is fine, but if she has a reduced capacity to carry the oxygen available then this could lead to fainting. She needs a full blood count to look for any anaemia and her haematocrit too. These are indices of how many red cells, the ones that carry oxygen to the tissues, she has and if low it would explain the faints.

If these are normal then she needs to take preventative measures. She must drink plenty of fluids on the flight. Dehydration can lead to a lower circulating blood volume and a lower blood pressure in some people. This can lead to a faint.

Finally if all is fine with her blood and fluid intake and the problem keeps happening then it may be worth exploring psychological issues like claustrophobia or fear of flying. Nothing a mild sedative in-flight won't cure.

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