In the wake of the global COVID-19 outbreak in early 2020, millions of people across the globe found themselves scrambling for hand sanitizer. While the Centers for Disease Control and Prevention note that cleaning hands at key times is one of the most important steps people can take to avoid getting sick and spreading germs, there are differences between washing with soap and water and washing with alcohol-based hand sanitizers.

The CDC notes that preventing the spread of sickness through handwashing is most effective when people know which method to use when cleaning their hands.

When to use soap and water

The following are common situations when the CDC advises using soap and water to clean hands.

• Before, during and after preparing food

• Before eating food

• Before and after caring for someone who is sick

• Before and after treating a cut or wound

• After using the bathroom, changing diapers or cleaning up a child who has used the bathroom

• After blowing your nose, coughing or sneezing

• After touching an animal, animal food or treats, animal cages, or animal waste

• After touching garbage

• If your hands are visibly dirty or greasy

When washing with soap and water, the CDC advises people to wet their hands with clean running water (warm or cold) and applying soap. Lather the hands by rubbing them together with the soap, making sure to scrub all surfaces of the hands, including palms, backs, fingers, between fingers, and under the nails. Scrub for 20 seconds before rinsing hands clean under running water and drying your hands, be it with a clean towel or air drying.

When to use alcohol-based hand sanitizer

Hand sanitizer should not be applied to hands that are dirty or greasy. Hands that become dirty or greasy after activities such as gardening or fishing should be cleaned with soap and water. The CDC advises using alcohol-based hand sanitizer:

• Before and after visiting a friend or a loved one in a hospital or nursing home, unless the person is sick with Clostridium difficile (if so, use soap and water to wash hands).

• If soap and water are not available, use an alcohol-based hand sanitizer that contains at least 60 percent alcohol, and wash with soap and water as soon as you can.

Children should always be supervised when applying alcohol-based hand sanitizer. When using alcohol-based hand sanitizers, the CDC recommends covering all surfaces of the hands with the product before rubbing hands together until they feel dry, which should happen after roughly 20 seconds.

Clean hands can prevent the spread of disease. Knowing which hand cleaner to use in certain situations can be an especially important preventative measure.