Most travel illness is one of four things: a stomach upset, something a mosquito gave you, heat or sun, and a motorbike accident. Three are largely preventable and the fourth is entirely so.
None of this is medical advice. Book a travel clinic appointment six to eight weeks before you go — several vaccine courses need multiple doses, and it is the single highest-value hour of preparation available.
Vaccinations
Commonly recommended by region: hepatitis A and B, typhoid, tetanus and diphtheria boosters, rabies for rural or long-term travel, Japanese encephalitis for rural Asia, meningitis for the African meningitis belt.
Yellow fever is sometimes legally required rather than advised — several countries demand a certificate on entry if you have come from an endemic country, and it is checked at the border. It takes ten days to become effective.
Rabies is worth a specific note. It is essentially always fatal once symptomatic, it is present in dogs and monkeys across much of Asia and Africa, and pre-exposure vaccination buys time rather than removing the need for treatment. Any bite or scratch from a mammal in an endemic area is a medical emergency.
Malaria and mosquitoes
Malaria prophylaxis is not optional in high-risk areas, and which drug depends on regional resistance. Take the full course, including after you leave.
Dengue, chikungunya and Zika have no prophylaxis, so not being bitten is the only protection: repellent, covered skin at dawn and dusk for malarial mosquitoes and in daylight for dengue’s, and a treated net where rooms are unscreened.
Stomach illness
Close to universal on a first long trip and usually three unpleasant days. Safe water — including ice and toothbrushing — hot freshly cooked food, and hand washing reduce it substantially.
Rehydration salts are the treatment. Carry them; almost nobody does. See a doctor for blood, high fever, or anything lasting more than a few days.
Altitude, heat and sun
Altitude above about 2,500m produces symptoms in most people, which pass in two or three days. Symptoms that worsen mean descend immediately. See the Andes and Everest pages.
Heat exhaustion creeps up; heat stroke is an emergency. Sun at altitude and on water is far stronger than it feels.
The kit
Rehydration salts, painkillers, antihistamines, blister treatment, antiseptic, plasters, prescription medication in labelled original packaging with a doctor’s letter. Pharmacies worldwide are well stocked and cheap; you do not need to carry a chemist’s shop.
Insurance
Check it covers your actual activities — trekking above a stated altitude, diving, riding a motorbike — and includes medical evacuation and repatriation in the millions. See the insurance guide, and the health guide for the full version of this page.