Q: How can I prevent myself from getting the stomach flu?

A: Stomach flu, or viral gastroenteritis, is very contagious and can come on without warning. Symptoms usually involve vomiting, frequent diarrhea, and some abdominal cramping. Most people recover within several days without drugs. But if you notice blood in your diarrhea, contact your primary care physician immediately; it could be a sign of something more serious.

The virus can spread quickly.

The culprit is almost always poor hand-washing: Someone uses the restroom or changes a baby's diaper, doesn't wash thoroughly, and then touches a surface. You then touch that same surface and pick up the virus. So, the best way to keep yourself from getting sick is to wash your hands very well and very thoroughly, especially before you eat or prepare food.

Here's how to wash your hands: Wet them thoroughly, put some soap on, and rub with the lather for at least 20 seconds (enough time to sing the "Happy Birthday" song). Rinse with clean water, and dry your hands with paper towels or under a dryer. Soap and water is the best way to keep clean, but if neither is available, hand sanitizers can substitute.

If you do get stomach flu - it can have several causes, none of them actually flu - it is important to stay well hydrated. Most hospitalizations related to gastroenteritis are due to dehydration, especially in young children. Take small, frequent sips of water, sports drinks, or juice - your body will tolerate small sips best. If you are unable to keep fluids down, contact your physician; prescription medications may be able to help with nausea and vomiting.

And remember: Wash your hands!

- Dr. Charmaine Chan

Charmaine Chan, D.O., is a family-medicine physician with Philadelphia College

of Osteopathic Medicine.