International travelers may be subject to certain stresses that may lower resistance to disease, such as crowding, disruption of usual eating and drinking habits, and changes in climate and time zone. These changes may lead to nausea, indigestion, extreme fatigue and insomnia. The time needed for complete readjustment depends on the number of time zones crossed but may take up to a week or more. If you have had problems with "jet lag" in the past, a short acting sleeping pill may provide some benefit.

Activity in the setting of excessive heat and humidity may lead to heat exhaustion from loss of water and salts. The maintenance of adequate hydration under these conditions is important. Excessive exposure to the sun can lead to sun-stroke and severe sunburn, especially in countries closer to the equator. You should bring a hat and use sunscreen liberally.

Traveling in high altitudes may initially give rise to insomnia, nausea, headache and altitude sickness, even in young and healthy persons, and can cause distress to those with cardiac or pulmonary conditions. Rapid ascension to sites in the Andes or Himalayas put travelers at greatest risk. A medication, Diamox, may speed the acclimatization process.

Insects are the route for many diseases in tropical and sub-tropical regions. Travelers should try to protect themselves from mosquito and other insect bites by:

Wear long-sleeved clothes and trousers when out after sunset.

Avoid dark colors, which attract mosquitoes.

Use insect repellent containing DEET.

Sleep in properly screened quarters or use mosquito netting at night, taking care to tuck in the net under the mattress. Impregnating the net with permethrin may improve protection.

Accidents are the major cause of death and serious disability while traveling. Driving accidents are the most common type of accident. If you are driving, be certain to find out in advance if the roads are well kept, so you can be prepared, Avoid non-essential night-time driving. Other major accidents include drowning, carbon monoxide poisoning, electric shocks, and drug reactions from dangerous drugs. Do not buy medications "over-the-counter" unless you are familiar with the product.