For many of us, hand sanitizers are part of the toolkit that we use to keep ourselves and our loved ones healthy. But is it really effective in dodging bacteria and viruses, such as the coronavirus that has been impacting people around the world? It can be, if used correctly.

Studies show the convenience of hand sanitizer can keep people from spreading germs to others. It’s quick, portable and easily found in public spaces, allowing people to clean up when soap and water aren’t available. But to use hand sanitizer effectively, the Centers for Disease Control and Prevention have guidelines to follow. Hand sanitizer must contain at least 60% alcohol, which is the ingredient that kills viruses and microbes. Most hand sanitizers sold in stores include at least 62% alcohol.

To use hand sanitizer correctly, the CDC says to squirt a quarter-sized amount of gel into the palm of your hand and rub the hands together until they are dry.

Although hand sanitizer can be effective, it cannot substitute for proper hand-washing with soap and water. Hand sanitizer does not kill everything, including the stomach bug norovirus, parasites and the diarrhea-causing bacteria Clostridium difficile (klos-TRID-e-um dif-uh-SEEL). You should not use hand sanitizer to clean your hands if they are noticeably dirty, grimy or greasy, as the product cannot effectively break down those particles.

To properly wash your hands, hum the “Happy Birthday” song twice as you lather soap under warm water, scrubbing gently at the back and front of your hands and between the fingers.

Whether it’s hand-washing or hand sanitizer, keep your hands clean to keep you — and others around you — healthy.