This is a checklist of the main essentials that you should consider. Some of the items listed require a doctor's prescription: they are intended for use in circumstances where skilled medical care is not available. Clearly such medication needs to be prescribed for you by a doctor who has given you careful (and, ideally, written) instructions about its use, and about any side-effects and problems.

Make sure all medicines are easily identifiable: keep them in their original container. When possible, ask your pharmacist to dispense drugs in blister packs – these travel best and are easiest to identify. They also save space, and can be kept in small, resealable plastic bags or pouches.

Allergies

Antihistamine tablets are sometimes useful for treating allergic skin reactions; Piriton or Clarityn (less likely to cause drowsiness) are suitable choices. People suffering from severe or potentially life-threatening allergies should carry their own emergency supply of adrenaline.

Altitude sickness

Some experts advise using the drug acetazolamide (Diamox) to prevent mountain sickness. For emergency use, it may also be worth carrying a supply of dexamethasone tablets to buy time in the treatment of acute mountain sickness.

Antibiotics

For longer or high-risk trips, I also advise taking a broad- spectrum, prescription antibiotic for treatment of troublesome intestinal infections. The most suitable drug is ciprofloxacin, which can be taken either as a single dose, or as a more conventional course. In more remote places, medication for treatment of amoebic dysentery and giardia (such as Fasigyn) may also be worth carrying, in case skilled medical care can't be found.

Antibiotics and anti-fungal drugs

For long-term travellers venturing far from the beaten track, a supply of broad-spectrum antibiotics may also be worthwhile. An antibiotic like co-amoxiclav can be used to treat a variety of infections, including common infections of the skin, sinuses, and chest. Fungal infections such as athlete's foot, groin infections and thrush, are common in tropical conditions — so it is also worth taking an anti-fungal preparation, such as Canesten.

Anti-diarrhoeal drugs

Diarrhoea is seldom a medically serious condition, but can turn a long journey into a sophisticated form of torture. For troublesome symptoms, it is strongly advisable to travel with a supply of loperamide (sold as Imodium or Arret), which is fast- acting and safe.

Anti-malarials

The best choice of malaria medication for a particular trip is a matter for discussion at your travel clinic, prior to departure. Do allow plenty of time in advance of your trip — some anti-malarials need to be started between two and three weeks before you leave. If you need rabies vaccine, that course may need to be completed before you start taking the tablets. Besides taking preventive medication, we strongly recommend travelling with insect repellents, mosquito killers and mosquito nets.

Bite creams

Take a tube of Eurax cream to relieve itching from insect bites (avoid anti-histamine creams — they may cause sensitisation). If you suffer from severe reactions to insect bites, your doctor may prescribe a more powerful, steroid cream if you need one.

Blood and intravenous fluids

These are often talked about, but are quite impractical to travel with. Accidents are the commonest reason for travellers to need a transfusion, and taking precautions to avoid accidents is the most effective measure to avoid the necessity of a blood transfusion. Knowing your blood group can make it easier to find a donor in an emergency — embassies keep a record of screened donors willing to help. Alternatively, join the Blood Care Foundation, a charity that undertakes to supply blood for transfusion in an emergency.

Cold sores

These are often triggered by strong sunlight, cold and wind. If you are prone to them, use high-factor sunblock on the lips, and consider taking acyclovir cream (Zovirax) for treatment.

Colds and sinusitis

Travel with a decongestant spray (e.g. Sinex) to avoid discomfort caused by pressure changes during air travel.

Constipation

Dehydr ation, jet lag, dietary changes (including low-fibre airline food) and an initial reluctance to use dirty toilets all add to this common problem. It may be worth travelling with a small supply of natural bran (or bran tablets).

Dental emergency kits

These often seem appealing, but are in fact of very limited value. Any likely problems should be dealt with at a check-up prior to travel, and the best person to advise on the likelihood of DIY repairs becoming necessary is your own dentist.

Eye infections

Minor infections are common in travellers to tropical countries and contact lens wearers. It is worth travelling with antibiotic drops in case of trouble (gentamicin drops do not need refrigeration, and can also be used as ear drops for infections caused by swimming).

First aid kit

Minor injuries are common, and need much more care in hot climates than they normally would at home in order to avoid infection. It's worth buying a small pack of Band-aids and dressings, plus a small bottle of liquid antiseptic, such as betadine. A supply of non-adherent dressings can also be helpful for dealing with slightly larger wounds. The other essential is something capable of holding together the edges of a clean, gaping wound if medical care cannot be obtained: Steristrips and similar adhesive tapes are useful.

'Flu

Depending on the nature of your trip, consider travelling with a supply of Relenza, the new anti-viral flu medication, which can be used to abort an attack of the disease. Research has shown that it may also be of value in preventing 'flu.

Insect repellents

Insects spread not only malaria, but also dengue fever, many forms of encephalitis (such as the variety that caused such havoc in New York recently) and other diseases not easily preventable with vaccines or medication. Repellents dramatically reduce the risk. DEET is the chemical repellent most widely used, and comes as a liquid, spray, gel, on wipes and in sticks; high concentrations are more economical and long-lasting, but should be used carefully. DEET can be applied to exposed skin and also sprayed or impregnated onto clothing. In addition, the insecticide permethrin can be applied to clothing and mosquito nets; it lasts weeks or months (and survives washing) and it kills mosquitoes, rather than merely redirecting them towards somebody not using repellent. An alternative choice is a lemon eucalyptus preparation sold as Mosi-guard. Some people prefer the smell of this, though it is not as effective as DEET.

Mosquito killers

Use a mosquito killer at night — mosquito coils are suitable for use outdoors, or where there is no electricity. Otherwise, use the plug-in variety. Mosquito nets are increasingly important, with the continuing spread of drug-resistant malaria. Ideally, use a net that has been impregnated with permethrin — this means taking your own rather than buying a net of unknown origin on arrival at your destination.

Motion sickness

The best choice of medication is largely a matter of individual preference. There is very little objective difference in effectiveness between the many products available. Many products have side-effects such as drowsiness. Whatever your choice, take the medication well in advance of trouble — most tablets are useless once vomiting starts.

Oral rehydration solutions

Sachets containing oral rehydration powder (which is added to water to make the solution) are ideal for prompt treatment of dehydration caused by diarrhoea, which is the most important consequence especially in children and older travellers. You should also know how to make your own ORS if required.

Painkillers

The choice is between a milder type, such as paracetamol, and something a little more powerful, such as ibuprofen.

Salt

Anyone travelling to extreme hot climates should increase salt intake to reduce the risk of heat illness. Take a small supply of ordinary table salt (rather than salt tablets, which may cause stomach irritation and do not always dissolve) to add to drinking water during acclimatisation: a quarter teaspoon per pint (just below the taste threshold) should be added to all drinking water.

Sterile needle kits

In many developing countries, there is a high potential for the spread of HIV and hepatitis B through non-sterile needles, syringes and other medical items. These simple, basic supplies may not be widely available; and even if they can be found in the capital city, don't expect them to be available in a poor, rural clinic at the moment you might need them. Most travellers to developing countries should take their own: the best way to do this is to buy a ready-made commercial kit rather than to attempt buying the items individually.

Sunburn

A supply of high-factor sunscreens (SPF 15 or higher) is essential for almost any outdoor activity, especially at altitude. Water-resistant sunscreens are also available, and last longer on the skin. Choose a brand that gives protection against UVA as well as UVB.

Water purification supplies

My own preference is either for iodine tablets (such as Potable Aqua) or for solution (the dose is four drops of two per cent tincture of iodine per litre of water — wait 20 minutes before drinking). There is also a wide choice of water purification gadgets that are effective and simple to use, such as the PentaPure Travel Cup, if you have enough room in your luggage.