Changes are made by the Centers for Disease Control and your doctor may see a special need for you based on your health history. Many doctors suggest Hepatitis B, although you need to begin the vaccination about 6 months prior to travel. Eat foods that are cooked, fruits and vegetables that you can wash and peal yourself, and drink bottled water. Koreans have a very good understanding of sanitation and clean food thoroughly, but any time your body takes in new foods, etc., it is a good idea to take along a supply of Pepto Bismol, Imodium and the like. While water at major hotels is fairly safe, we suggest you stick with bottled water as much as possible.
Bottled water is readily available.
Make sure you brush your teeth with bottled water, too. If you are taking any medication, carry enough of that medication to see you through the trip. Medications should be carried in their original containers. Contact lens solutions are not readily available, but they're not impossible to find either. Your best bet is to have with you everything you need for your eyes.