Q & A Library

Most of us carry up to 10 million microbes on our hands. We pick up colds, flu and other illnesses via hand-to-mouth or hand-to-eyes transmission - our hands come in contact with objects that have been touched by someone with a cold or flu and pick up the bugs that caused it. For this reason, it's very important to keep your hands clean.

If your hands are visibly dirty, soap and water are best for cleansing. Sanitizing gels aren't as effective as soap and water to remove dirt, food or anything else that you can see on your hands. However, they can work well on unsoiled hands when soap and water aren't available.

Unfortunately, not all the sanitizers on the market contain enough alcohol to kill the microbes that lurk on your hands. When buying hand sanitizers, be sure to check labels carefully and choose products with alcohol concentrations of 60 to 95 percent. The alcohol in the gels strips away the outer layer of oil on the skin, killing any microbes present. For the gels to work best, you need to squeeze a dime-size dollop on your hands and rub it in for 30 seconds. If your hands dry in less time, you probably didn't use enough gel.

When you're at home, soap and water are best for cleaning your hands, but you might want to use a gel afterwards as well, especially if you're in close contact with someone at high risk for infection (newborns, the very old, or someone whose immune system is suppressed). It's also a good idea to use a hand sanitizer when you're in direct physical contact with someone who has a cold or flu, a skin infection, or diarrhea, or if you work in a child-care center, health care facility or other situation where infectious diseases are common.

Andrew Weil, M.D.