What Causes a Cold or the Flu?

Your Prevention Plan

"Hand washing is number one, two, and three on any list of ways to prevent infection,” says Susan Rehm, M.D., medical director of the National Foundation for Infectious Diseases. Scrub for at least 20 seconds with soapy water. When you have no sink, an alcohol-based antibacterial hand gel (like Purell) can help. Enough sleep, a balanced diet, and regular exercise can also help make you less vulnerable.

To avoid the flu, get vaccinated. The vaccines may thwart 70 to 90 percent of flu cases, and even if a strain slips through, your illness should be milder. Schedule a vaccine in September or October, well before the peak of the flu season.

If your family members are sick will you get sick, too? With a cold, you’re most contagious two to three days after the first symptoms appear. You can pass the flu along one day before symptoms develop and up to five days after becoming sick.