When used correctly, hand sanitizer can be an important tool in your cold- and flu-fighting arsenal.

Plain soap and water are the best way to remove germs from your hands. But when soap and water aren't available, an alcohol-based hand sanitizer with at least 60 percent alcohol is the next-best thing.Look for a product with a main ingredient of ethyl alcohol, ethanol, isopropanol, or isopropyl, said Kocher, who follows the CDC's guidelines for hand sanitizers. Sanitizers with these types of alcohol are more effective for killing germs.She noted that non-alcohol-based sanitizers typically contain benzethonium chloride, which is not as effective at eliminating bacteria and other germs.To properly use hand sanitizer, apply a generous amount to the palm of one hand.Rub the sanitizer over both hands until your hands and fingers are dry, but do not wipe off excessive sanitizer before it has dried.