Business travellers Jet lag - to minimise jet lag, drink plenty of water before, during and after the flight; avoid alcohol and beverages such as coffee and tea; allow time for rest and to adjust to the local time zone; Food and water hygiene - always drink boiled or bottled water and eat properly prepared cooked foods; Safe sex - don't have casual sex with strangers and commercial sex workers. Practise safe sex. Alcohol - avoid drinking excessive alcohol which may loosen your self-control; Decision-making - avoid making important decisions immediately upon arrival after crossing many time zones within a short time. Children Children adapt to time and climate changes better but are usually less resistant to illnesses. There aren't as many suitable vaccines available for young children and some, even if available, are less effective on them. Up-to-date immunisation - make sure your children's immunisation is up to date. By the age of two, children should already have completed primary immunisation. The family doctor can advise on any necessary extras. Anti-malaria precautions - most but not all anti-malarial drugs are safe for infants so check with doctors; most of the symptoms of malaria in children may not be typical, so seek medical help immediately if a child develops what appears to be a febrile illness. Discomfort on flights - minimise babies' discomfort due to changes in cabin pressure: giving them a bottle, as soon as the plane descends, usually helps; carry a 24-hour supply of food in case of extensive delays. Breastfeeding is convenient and helps to prevent diarrhoea. The elderly Elderly people need more time to adjust to changes in temperature, altitude, and culture, but age is no longer an obstacle to travel. But because they are more likely to have long-term illnesses such as diabetes and high blood pressure, extra care should be taken. Blood clots - to prevent deep-vein thrombosis try to move around as much as possible and perform simple exercises while in the aircraft. Elevating the legs should help circulation.