Dr 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. Exactly a year ago my wife had an operation for malignant melanoma in which thirteen lymph nodes were removed from her armpit. She developed a clot on the lung, but this was quickly treated with warfarin. The cancer hadn't spread and since then she's been fine, and we've made several trips together involving short haul flights to Europe.

In April, however, we're planning to fly to Atlanta (9 hours). She's confident that she'll be fine, but is there any medical reason why she shouldn't make such a long flight? Your advice welcomed.

A. I do not see that there should be any real problems. The removal of lymph nodes in the armpit can make her prone to swelling in the arm, and on rare occasions this could bring on a thrombosis ni the veins of the arms, rather like a DVT in the leg.

But this is “hen’s teeth” as we say medically. The reason DVT’s develop in the leg in-flight is that the legs are folded, cramped and move little. Hence the blood gets static and clots develop. As long as she does not let her arm hang there with no movement for the full 9 hours she will be fine.

The thing to watch, though, is other melanomas developing. There is an increased risk if she has had one before, and it can get hot there in the Southern States.

Make sure she has plenty of sun block, and if you see any spot or freckle getting darker, or irregular around the edge, then get it to a dermatologist as soon as possible.

Q. Please could you advise me where best to take my 13 year old son on holiday over Easter? He has been unwell since last September and as yet we have no definite diagnosis. It is possibly Crohn's disease. He is quite depressed and I would like to take him somewhere where he could relax and gather some strength. I do not have a great deal of money but helping him feel better is my main consideration.

A. I assume that if the inflammatory bowel disease, Crohn’s, is suspected then he must be having symptoms of loose and frequent motions, tiredness, and maybe some joint pains too.

So you must go somewhere where the food is not too spicy or strange which could worsen the problem.

On top of this, long flights will be tiring and expensive, and there’s got to be something to cheer him up cheaply at the other end.

I have a couple of thoughts, and welcome any more from readers.

Eurodisney by train would fit the bill.

But for something a bit more unique, why not try Western Ireland. Easy to get to, good simple food that he would be used to and, importantly, dolphins.

Just being near one, close enough to touch will cheer up the most hardened sad soul. Nature’s Prozac, especially for a teenager.

Q. I'm going to the Galapagos Islands next month with my wife who has happily found out that she is 6 weeks pregnant. My question is will it be safe for her to travel there and maybe also take in a trip to the Amazon as we have some extra time in Equador, or should we be rethinking the whole destination?

A. I don't think you have to necessarily cancel the trip at this stage, but you may well have to adapt it to fit in with your wife's pregnancy.

The main thing is with immunization and malaria prophylaxis.

Pregnancy is divided up into 3 thirds called trimesters, and the most crucial time for the development of your child is in the first trimester. It is during these 12 to 14 weeks that all the sensitive embryonic developments of limbs and other organs occurs, and anything that can have an effect on the fetus here will cause far more serious problems later. 2 of the vaccines your wife should have for an extensive trip to Equador can theoretically cause problems if given in the first trimester. These are Yellow Fever and the newer Hepatitis A shot. Now, she will mainly be at risk of getting Yellow Fever if you both go down to the Amazon, as it is a disease spread by mosquitoes that are lowland and forest based. So I suggest that if she hasn't previously been vaccinated against this (within the last 10 years) then she should avoid it and that you both stay away from the Amazon Basin, but head to higher ground if you have some spare time. I can recommend Banos south of Quito.

She is unlikely to encounter Yellow Fever in the Galapagos, so that should be fine. As for the Hepatitis A shot, I would recommend she have the old style immunoglobulin as that is much safer in this trimester, but sadly it is getting harder for us doctors to get hold of as the manufacturers are annoyingly ceasing its production in favour of the more expensive alternatives.

She will need to take malaria prevention whilst away, but for that part of Equador the combination of chloroquine and paludrine should be fine, and they are both safe to take in pregnancy.

Other issues in her case are that whilst you are enjoying the close up animal encounters and snorkelling with sharks, she may well be throwing up in a bucket every morning. Morning sickness is a problem up to 14 weeks when levels of the hormone HCG drop, and as she will be also on a boat for a lot of the time then it might be an idea to take antiemetic tablets with her. Probably the best ones in her circumstances are called metaclopramide and her doctor should give you a scrip for these.

As she doubtless knows she must avoid certain foods at this time, especially undercooked eggs and soft cheeses. I suggest that you both learn the Spanish for these items, so when you are presented with a plate of food of ambiguous origin, you can ask the chef quickly and politely if it contains these products. It beats entertaining other diners with your chicken impressions as you try to fathom the food's contents in sign language.

She cannot dive of course but snorkelling would be fine at 10 weeks of pregnancy. I think the real message here is that if you are a keen traveller then get both Hep A and Yellow Fever in early as they both last 10 years and similar problems with a later pregnancy wouldn't occur.

Q. I have recently undergone a knee replacement on both knees. It is now 3 weeks since the operation but I have been invited skiing by some friends in March. My question is this, will I be fit enough by then and is there anything I can do to increase my chances of being fit to ski by then?

A. It seems you have really picked a sport here that is going to test your knees.

A knee replacement is quite a big operation to have, and the fact that you have had one on both knees obviously doubles your potential for harm if you come a cropper on the slopes.

The usual guidelines for an operation to return you to normal afterwards is 8 to 12 weeks, but the doctors then only expect you to do a little light exercise.

Skiing puts a tremendous strain on your knees as they have to be flexed or bent when you go down the slope to act as shock absorbers for the rest of the body. If you skied with straight knees not only would you fall over far more easily but also the chances of causing hip or lower back problems is increased.

So the question is, is can you effectively keep your knees bent for the time it takes to get down a run and also to do it several times a day. By going in March you are close to the time when you should be fine to do it but there are a few other mitigating factors. If you are overweight then you will be putting more pressure on the knees so you must make sure you are as close to your normal weight as you can possibly be before going. Another factor is what we call quadriceps wasting. These are the muscles in the front part of your thighs that are again used a lot in keeping your knees flexed. If the condition that necessitated your knee replacements has let these muscles in your leg waste away then you will find it very hard to keep up with your fellow skiers.

My advice is that March may be a little too early to get back to a full on skiing adventure like you may have enjoyed before you got your knee problems. But with some good physiotherapy, working on building up your quadriceps, and losing as much weight as is deemed healthy you will probably be able to at least go on the green and blue runs, but again I would advise that you to stay away from mogul fields or particulary bumpy uneven runs as they will again cause extra grief to your post op knees.

So long flat smooth runs with as little turning as possible, why not try the USA.

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. I'm flying to Antigua next week with both my children. However the oldest Zoe, who is 3 has come into contact with another child who has since developed chicken pox. What are the chances she will get it too, and will she be allowed to fly if she does have it?

A. This is a question that I am being frequently asked at the moment as we are right in the middle of chickenpox season.
I understand your concern as it is impossible to tell if Zoe will contract it from her friend and when it will come. You obviously don't want to cancel your holiday only to find that she remains in perfect health, and neither do you want to turn up at the check in desk just as the spots erupt to be told you cannot board.
There is a lot of conflicting information around but for your circumstances this is what I advise.
The incubation period for chickenpox can be anything from 7 to 20 days. So you can have a long wait to see if Zoe is going to develop the illness. However , during this incubation she is not contagious until she is about to come up with the rash. You can tell this is about to happen as she will develop symptoms like that of a cold. She will be snuffly, may have a fever and be generally unwell and clingy. If this happens the chances are that she is about to erupt in blister like viral filled vesicles, and, as she will be infectious you should cancel the flight.

If she remains well over the next week then she is unlikely to be incubating the illness and you should go ahead with the holiday as planned. Of course there is a chance that with a maximum of 20 day incubation that she could go down with the illness whilst you are in Antigua.

Once she has the spots then she will be infectious to others until the very last spot has finally crusted over and fallen off and should not fly.

Chickenpox is caused by a variant of the Herpes virus, and is spread by respiratory droplets, so if she coughs or sneezes then she can infect anyone in the vicinity.

This creates the difficulty with flying as air is recircrculated around the plane so others may breathe it. Therefore there is a danger that any passenger may contract the disease. This can be a disaster if anyone on board has AIDS or is immunosupressed after a transplant as chickenpox can be fatal in these people.

So if Zoe stays well this week feel free to board the plane and enjoy your holiday, but if she begins to fall ill then cancel as soon as you can. This will be reimbursed by your insurance policy.

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.

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.

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.

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.

A. This may well be a close call.

Don't worry about the statin, it just lowers the cholesterol and is fine at altitude.

However the beta blocker could be a problem. It's a drug that reduces blood pressure by slowing down the heart.

At altitude, as the oxygen is decreased, your heart would compensate by increasing its beats per minute rate before other physiological changes happen. With a beta blocker it cannot. The issue here is that you must really make sure you do the absolute minimum whilst you wait to get used to the altitude. It can take up to 3-4 days to acclimatise, but on the beta blockers give it at least 5. If you go for any trekking take it really easy up the slopes.

An alternative may be to switch to a different blood pressure tablet. Try losartan, one of the newer ones that won't slow your heart rate.

A. This is the time of year that tearful parents bid farewell to their now adult children. I've done it to my mother and my child will do it to me someday. Perhaps, the modern equivalent of a young Masai killing his first lion. The perils are different but it is possible to go much better prepared than carrying a rusty assegai!

As he is asthmatic he must take a good supply of inhalers. Your GP will be happy to prescribe enough for the trip and it depends what his daily use is, as to how many that is. Inhalers have a long shelf life and don't need to be kept chilled. It is advisable to always carry one in a waist belt rather than have the whole supply in a rucksack. Theft of his possessions is always a risk, so make sure it doesn't cause a medical problem as well by not keeping all the eggs in one basket.

I also suggest that he takes some broad spectrum antibiotics in case of a chest infection. Amoxicillin should be good enough unless he has a penicillin allergy, though my favourite antibiotic for travellers, ciproxin, would be better as it can cover a wide range of infections, from bowel to ear.

If he is diving, take a "fit to dive" medical certificate as some Asian countries will not let him dive with asthma without one.

There has been some interesting research lately about asthma and volcanoes. They have been implicated in the precipitation of bad attacks, rather like thunderstorms have been. It could well be the ash from the lava, but I suggest doubling his inhaler dose if he is near one.

Take a good travel health guide. Lonely Planet do an excellent range. Small and portable they are invaluable and cost little.

Finally he must have good travel insurance cover. Make sure it includes any activity he may do and if it covers diving, check the depth it covers too. The cheaper ones only go to a shallow depth, he will need cover to 30 metres depth at least.

Do not worry though, the health services are excellent in Asia, and with e-mail he can get quick advice from home if he needs.

And don't forget the shots and antimalarials.

Q. My wife is 36 weeks pregnant with our second child.

We are going to the South of France in a week on the Eurostar train.

My question is do you think she will be fit to travel all that way and back, and will we need a note to show them when we get on at Waterloo to say it's OK to travel on the train.

A. I would suggest you check with the operators of the Eurostar service as to what they exactly need.

The only real comparison, of course, is with airline travel.

Here International flights usually rule that no one can fly after 32 weeks of pregnancy, but they can end the rules and often let people fly up to 36 weeks if they have a doctors note to say all will be well.

To be frank I don't know how your GP can guess that all will be well in a couple of weeks as we know that premature labour catches everyone by surprise.

If you need a note your doctor will check that the babies head is not fully engaged and there are no contractions. If all is clear then you should be fine.

For the return leg don't travel if there are any signs of labour.

Other useful tips are to make sure you have the E111 form with you. This allows you free health care in France if you needed to see an obstetrician.

On the trip itself make sure she gets up to take a walk up and down the carriage every hour.

The pregnant uterus can press on the venous drainage from the legs and so increase the risk of a DVT. So a little stroll will sort that out.

Finally, and I'm sure you were going to do this, but it's best if you carry all the luggage!

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 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. 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.