From sunstroke to moped mishaps, ship's doctor Ben MacFarlane knows how health problems can ruin a holiday. He advises on how to stay well abroad

There are some things that you can never predict on holiday. After spending years as a repatriation doctor – at the same time as practising medicine in London – and travelling around the world aboard a luxury cruise liner, I've seen countless holidays ruined by poor health. Drugs, drink, sun and sea- sickness: they all have their perils. You might get a heart attack, or be involved in some terrible accident. But, even if you can't prevent those things from happening, there are certain things you can do to prepare. Simple things that can be accomplished with a little planning and a little thought, but which might just make all the difference.

Get your insurance in order

Never travel without insurance. This is the thing I always hark on about. I've seen heartbreaking cases where people clock up enormous bills and don't have the means to pay them. If there's an excuse for your insurance company not to pay out, they'll use it. So make sure you don't have any undeclared conditions and that your insurance company is a good one. Also, never underestimate the importance of a European Health Card. If you're travelling in the Europe Union, get a European Health Card. It's free and means you can get your healthcare free at the point of delivery. If you're going outside the European Union, make sure you have some way of paying for healthcare. It's very easy to assume that it will be free when you are in this country – but in fact there is usually a lot of paperwork to be done first.

You also need to be sure, in case of emergency, that your vital information is accessible. Carry important documentation – your insurance details, your travel papers, your GP's information – somewhere prominent. If you are travelling with someone else, give them a photocopy. That way if you are pickpocketed, or fall unconscious someone has a spare. The term "ICE" – in case of emergency – is increasingly recognised, so put it in your mobile phone.

Beware foreign roads

Road accidents are one of the biggest causes of claims. People think they can go out to Greece having never ridden a moped in their life before, put on a pair of shorts, and go out on a dirt road with no helmet. The same is true of hiring a car. You need to remember that it's a strange vehicle that you have never driven before, and that, in driving on the left-hand side of the road, Britain is the exception, not the rule. And it's not just when driving that the roads can be a hazard. Another big problem comes when people crossing don't realise which side of the road drivers use. I've seen it happen: a whole family stepped out in front of a bus, and the little girl got her legs trapped under. All the passengers had to disembark and lift the bus up by hand. Fortunately, she was fine – just very scared. I doubt that family will be going on holiday for a while!

Sort out your medications

More and more people are going on adventurous holidays. It's no longer just a case of a week in Mallorca; nowadays people are climbing Kilimanjaro. People know they need jabs and pills, but all too often they don't realise how far in advance to get them. You can't just pitch up at the doctor's and ask for a yellow fever vaccination – it may well need to be ordered in. And, in the case of anti-malarials, remember to keep taking them when you are back. Feeling healthy doesn't mean you can give up. I've treated three malaria patients in the past week. It's not nearly as rare as one might think.

As far as your regular medication is concerned, remember to keep it in its original packaging. I came across a girl who had gone to Ibiza with her grandma. She went out clubbing and her grandma took what she thought was aspirin. It was ecstasy.

You should always take your prescription slips. If you run out and have to buy medicine abroad, it will come in very helpful.

Don't think yourself ill

When I've worked on cruise liners I encounter a lot of people complaining of seasickness. Interestingly, a lot of it is in the mind. Cruise liners are so stable that – short of major rough seas – you are unlikely to feel genuinely seasick. Still, lots of people assume that it is an inevitable part of the holidays. As soon as there are a few serious waves, everyone congregates around the sick bay. There's really very little I can do. I've seen queues of people, particularly elderly European ladies, forming outside the doctor's room expecting anti-nausea jabs.

Learn about food poisoning

The same is true of food poisoning. It used to be a huge hazard at sea, but it's amazing how much preventative work is done these days. There are daily swabs and the kitchens have higher health standards than any normal restaurant you will come across. Major outbreaks are very rare. Remember that just because a restaurant is expensive it doesn't mean it's a safer choice. Don't dismiss eating in the local cafes and bars. I've seen more food poisoning at smart restaurants and hotel buffets, where the food is kept warm, than at cafes where food is fresh and cooked in front of you. The British tend to go very over the top about foreign water. Most of the time it's ok. But when it is poor, it can give you very bad gastroenteritis. If in doubt, stick to bottled – but watch out for ice cubes and salad washed in water. It won't be mineral water! And make sure that if you are paying for water the bottle is sealed. It has become very common these days, particularly in the Third World, to refill empty bottles with tap water. So watch out.

Take exercise slowly

Many holidays nowadays give you access to incredible activities like climbing and surfing. People who have never been to gym before suddenly want to take a spinning class. So I've found that I've seen a lot of people with angina. They've spent three hours line-dancing but when you ask what their usual activity level is, it's walking down the road to buy a pack of cigarettes. No wonder they're not feeling well.

Don't over-indulge

People complain of symptoms, and think they have some terrible disease. In reality, it's a hangover. The most common trap is if you are staying somewhere on an all-inclusive deal, so you make a pig of yourself at the buffet and drink far more than you

are used to. Drinking doesn't just give you a hangover, it makes you do things that you wouldn't otherwise, which causes all sorts of accidents. Furniture on cruise ships is often very heavy or bolted down. People don't expect that. If you collide with a barstool, you might just end up with a broken leg.

Drugs are always dangerous, but on holiday it's even worse. For one thing, you might not have access to the correct facilities to deal with an emergency. Also, it can be harder to know what they have been cut with, or if you've been given dummies. The same is true of prescription drugs. People think it is a good idea to stock up on cheap generic drugs in foreign countries such as Malaysia. But the standards might be different, so steer clear.

Protect yourself from the sun

People can develop third-degree burns from the sun. Many don't realise it is just l ike being in a fire. The reason we have seen such a rise in cancers over the past 30 years is because it has coincided with a boom in international travel, and with people going off sun-seeking in Spain and Italy.

Quite apart from the long-term dangers of skin cancer, there's the risk of renal failure. If you get lots of weeping blisters you will lose fluid, and you may be dehydrated anyway, so the situation gets worse. It's a big problem. And it's not just about burned skin. Even if you get sunstroke, it can ruin your holiday. You will have to contend with nausea and headaches. Sunscreen alone isn't enough. You need to limit your exposure. There's a reason why in most very hot countries people spend the peak of the day indoors – it's only us that have this tendency to lie outdoors in the baking sun. And just because it's overcast, it doesn't mean there's no UV. In fact if anything there is the added danger, because the temperature will be lowered so people don't tend to realise how exposed they are. The presence of water can also be dangerous, because it superficially cools things down. If you are lying by a pool, dipping in and out, you may not overheat but that won't stop you from burning.

Be a cool parent

Travelling with children is a great idea. Remember: there are babies all around the world. Having said that, parents need to be very aware of the risks of sunburn, and not all vaccinations and medication will be suitable. But, apart from that, don't be scared to take your kids.

If you can, breast-feed. Breast-feeding is great. You'll need to check that any medication you're taking is suitable, but once that's done breast milk is the safest food. It doesn't go off, you don't have to prepare it and it won't get contaminated. Just remember to stay well hydrated, otherwise you won't have any milk to feed with.

And finally...

Before you head off, get your eyes and teeth checked and make sure you're fit. Even if it's a last-minute trip, the single most important thing is to get insurance. And remember: humans are always willing to help humans. If you do find yourself ill abroad, there are people to help. You can't just expect it to be exactly what you are used to at home, but at the end of the day, the standard of healthcare around the world is not bad at all.

'Cruise Ships SOS – The Life-Saving Adventures of a Doctor at Sea' by Ben MacFarlane (Hodder &Stoughton, £13.99)

Interview by Alice-Azania Jarvis