1. Colds and flus
"Cold and flu viruses can live on surfaces for anywhere from a few hours to a few days. Norovirus (a.k.a. stomach flu, with symptoms like diarrhea, nausea, and vomiting) can survive on surfaces for two to four weeks.
You can reduce your risk of getting ill by 30 to 50 percent with frequent hand washing. Use alcohol gel hand sanitizers, if you can't always get to a sink with soap while traveling. When purchasing gels, look for bottles that say 'sanitizer'—because that label is FDA-approved—and that have at least a 70 percent alcohol content."
—Dr. Charles P. Gerba, microbiologist, University of Arizona
2. Economy-class syndrome (a.k.a. deep vein thrombosis)
"Flights longer than eight hours increase your risk for DVT, a blood clot that forms in a vein, which can lead to fatal complications. Cases are rare, though. Out of every million travelers who fly, only about 27 are struck with DVT.
The risk factor tends to be found in people who have had heart failure, a history of pulmonary embolism, a hip or knee replacement in the last six months, or any neurological weakness of the legs. Medications that put people at risk include oral contraceptives and estrogen replacement therapy. Pregnancy also puts you at risk. But that doesn't mean you should stop traveling.
Prevent DVT by staying hydrated and exercising calf muscles by pumping your foot at the ankle and wiggling your toes and feet. When the flight allows it, get out of your seat and walk in the aisle. You want to have the blood flowing in your legs."
—Dr. Daniel Becker, professor of internal medicine, University of Virginia School of Medicine; co-author of the medical journal article "Air Travel and Venous Thromboembolism: A Systemic Review"
3. Jet lag
"It takes your body typically one day to adjust to each time zone traveled, so if you've gone through seven or eight time zones, it'll be about one week before your internal clock matches the actual time.
The main factors in resetting your biological clock are light exposure and melatonin. If you've traveled eastward, you can fool your body's reactions to the time zone by getting light exposure early in the day. If you've gone westward, you're trying to extend your day, so you want light exposure in the evening.
Melatonin (in the U.S.) is a clock-resetting agent. Adults traveling eastward can take three milligrams before going to bed upon arriving at their destination." It's less useful for westward travel, though.
—Dr. Robert Sack, professor of psychiatry, Oregon Health & Science University, with an expertise in sleep disorders
"Request a mid-ship cabin. Picture the ship like a child's seesaw: There's much less motion in the middle. If you feel queasy, situate yourself mid-ship on a low, outside deck, preferably standing up. Getting fresh air and staring at the horizon might help."
—Dr. John Bradberry, medical director, Carnival Cruise Lines
5. Food-borne illnesses
Follow the advice, 'Cook it, peel it, wash it, or forget it.' Thoroughly cooking food destroys bacteria. Fruits that you can peel, like oranges, are safe to eat. If you are going to wash the food, you have to wash it carefully. In some places, the water is a little risky."
—Dr. Ewen Todd, professor, Dept. of Advertising, Public Relations, & Retailing, Michigan State University; former director, National Food Safety and Toxicology Center, Michigan State University
6. Sunburn (especially for kids)
"Severe sunburns and excessive sun exposure increase the risk for skin cancer later in life. Liberally use sunblock with a sun protection factor (SPF) rating of 30 or higher and reapply every three or four hours.
You don't need to spend more money on sunblock with higher SPF ratings (such as 45 or higher) because there's no evidence those levels are more effective.
What counts is reapplying SPF 30 sunscreen frequently. Parents should also keep kids out of the sun during the hot hours between 11 a.m. and 3 p.m. Take a siesta!"
—Dr. Rick Malley, associate professor of pediatrics, Harvard Medical School; senior associate physician in the Division of Infectious Diseases, Children's Hospital Boston; Travel and Geographic Medicine Clinic staff, Children's Hospital Boston
7. Avoid germs on airplanes
"Jet cabins are unnaturally dry and suck moisture out of the mucos membranes in your mouth and eyes, whose immune cells and enzymes otherwise help break down invading pathogens. Staying hydrated keeps those membranes functioning well and protects your natural defenses against colds and the flu.
You could also use the little overhead vent above your seat, turning it on to low or medium power and adjust the airflow so it falls right in front of your face. This current may push away germs floating your way and prevent them from entering your eyes, nose, and mouth."
—Dr. Mark Gendreau, senior staff physician and vice chair of emergency medicine, Lahey Clinic, Burlington, Mass; co-author of the medical journal article "Medical Issues Associated with Commercial Flights"