Some vaccines must be given in a series over several days or weeks. You should see your provider as early as possible before your departure to find out what medicines or vaccines are advised and allow enough time for them to be given.

Hepatitis A can be contracted anywhere, including the U.S.

If you can, walk up and down the aisle of the plane. If traveling by bus or train, make the same effort. If traveling by car, stop and walk around every 2 to 3 hours, the CDC says. While seated, you can move your legs and stretch and flex your feet, which improves blood flow in your calves. Movement prevents blood from pooling. Wearing compression stockings and loose, comfortable clothing can reduce the risk of developing a blood clot. So can sitting in an aisle seat.

The best choice is the U.S. Embassy. Embassy staff can advise you on English-speaking healthcare providers or the best hospital in your locale.

Choose water over the other beverages listed. Caffeinated and alcoholic beverages dehydrate the body by speeding up the rate of urination. For optimum rehydration, drink 1 cup of water for each hour of flight time.

If you are in an area where water may be contaminated, don't use ice in your beverage, because the ice may be contaminated. It's safest to drink directly from the bottle or can, rather than from a glass, the CDC says. Also be careful of water on the outside of the bottle or can. Wipe the bottle or can dry before opening, and clean the area where your mouth will touch.

Stay away from uncooked vegetables and moist dishes such as rice that could have been sitting at room temperature. Also, eat fruits and vegetables that you can peel. This is safer than eating those that you can't peel.

Keep any medications in their original bottles and carry a copy of your prescriptions, along with a note from your healthcare provider if you take controlled substances. If you have a complicated or unstable health condition such as irregular heart rate or a serious respiratory disease, consider asking your provider for a letter that explains your condition and the treatment approaches that have worked.