Nothing beats washing your hands with soap and water to get them clean, but when that's not possible, using a hand sanitizer with a concentration of at least 60 percent alcohol (ethanol, ethyl alcohol, or isopropanol) is a great way to reduce the spread of germs and bacteria (that is, as long as your hands aren't visibly dirty). Experts recommend you apply enough hand sanitizer to wet your hands -- get in between all your fingers -- and rub your hands together until they're dry [source: Mayo Clinic]. But is there such a thing as too much hand sanitizer? As it turns out, maybe so.
Let's talk about your immune system. It's important to protect yourself against infection, but it's also good to allow some germs and microbes in. Without exposure to germs, you're actually not doing your immune system any favors -- you won't build up a resistance to the germs in any sneeze or cough that comes your way.