Three of the most common health problems that you may experience when traveling are jet lag, altitude sickness, and diarrhea. When you fly across time zones, the differing amounts of light can change your internal body clock, resulting in a condition known as jet lag. Jet lag may cause some symptoms that are bummers on a fun trip, including upset stomach, insomnia, and tiredness.

There are some things you can do to combat jet lag; for example, if you're traveling from west to east, you should stay out of the sun until the day after your arrival. If you're flying from east to west, go for a brisk walk as soon as possible after you arrive.

So what foods are safe to eat? Any foods that have been boiled are generally safe, as well as fruits and vegetables that have to be peeled before eating. Avoid eating uncooked or undercooked meat or meat that is not cooked just prior to serving.

You've probably heard that you shouldn't drink the water in some countries overseas, but did you know why? Water supplies in many developing countries are not treated in the same way as water supplies in developed countries; various bacteria, viruses, and parasites are commonly found in the water. Many experts suggest you drink only bottled water when traveling. If you need to use tap water, you should boil it first or purify it with an iodine tablet. Even if you're brushing your teeth, rinsing contact lenses, drinking a small glass of water to wash down pills, or adding ice to your drink, first take precautions to ensure the water is safe.

When you're packing, you'll want to include any medications and other medical supplies you use on a daily basis because they may be hard to find in another country if you run out. Even if you can find them, there's a good chance the formulations will be stronger or weaker than the ones you're used to. These may include any prescriptions you already take, such as inhalers, allergy medication, and insulin, as well as contact lens cleaners and vitamins. Packing an over-the-counter pain medication like acetaminophen and diarrhea medication is also a good idea. It's a good idea to pack some over-the-counter allergy medication even if you don't take it at home. People sometimes unexpectedly develop allergic reactions to the pollens and other allergens found in a new environment. Those with asthma or other allergies can unexpectedly react to these new substances.

Even if you watch what you eat and drink and get enough rest while you're traveling, you may still get sick. The good news is that you'll probably be able to find competent medical care. The key is knowing where to go. Most travel guides suggest you go to a hospital where English is spoken or U.S.-trained doctors can be found. For this reason, it's a good idea to always carry a written copy of your medical history with you.

Having such important information available in one place can help health care workers make appropriate decisions, and you won't have to worry about forgetting important information at a time when you're likely to be upset and not thinking clearly.

Before you leave your home sweet home, create a medical history form that includes the following information: