Is It Sanitary to Share Bar Soap?

Most of us have shared a bar of soap at some point, and might have asked the (somewhat philosophical) question: Does it clean itself?

The answer is no, soap doesn’t sanitize itself. But using a communal bar of soap probably isn’t a risk to your health, especially if you take a few precautions, says Kelly Reynolds, PhD, a professor in public health and environmental science at the University of Arizona.

Here’s what you need to know about how germs collect on soap and how to share a bar safely.

The Science Behind Soap Sharing

"Believe it or not, there have been quite a few peer-reviewed, published studies on this exact topic," Dr. Reynolds says. Most studies are on the older side, however.

Although it sounds logical, research says soap isn't self-cleaning, and that bacteria can stick around after a person washes up.

For instance, a study published in 2006 in the Indian Journal of Dental Research found that bar soap harbored two to five different types of germs, and a study published in 2015 in the American Journal of Infection Control found that about 62 percent of bar soaps in a hospital were contaminated, compared to just 3 percent of liquid soaps.

Some of the germs sitting on soap could include E. coli, salmonella, and shigella bacteria, as well as viruses like norovirus, rotavirus, and staph, Reynolds says.

However, it’s important to note that most studies don’t track actual disease outcomes, so the existence of germs on your soap doesn’t necessarily mean you’ll be infected.

How to Share Soap Safely

If you do need (or want) to share your soap, the habits below will reduce the risk of spreading germs to your community. These rules apply to all types of soap (like regular or antibacterial) and methods of washing (like hot or cold water).

1. Clean It Off

Soap isn’t self-cleaning, but you can certainly wash down your soap before or after use to remove any superficial dirt or germs.

2. Lather Up

"Bacteria like to stick to soap bubbles," Reynolds says. If you get the bar sudsy, more germs will be washed down the drain. She suggests a 20- to 30-second lather time.

3. Air It Out

Bacteria thrive in damp environments. Make sure the bar is able to air out, preferably with a draining soap dish. "As soap dries out, bacteria counts go down, which lowers the risk of transferring any bacteria," Reynolds says.

Alternatives to Sharing Soap

Liquid soap dispensers with a changeable soap bag are the safest option, Reynolds says. "We never find bacteria in these," she adds.

And remember that you’re washing your hands in the process of touching bacteria, so there is a readily available solution to germ exposure. Lather with the soap for 20 seconds and scrub all parts of your hands, then rinse and dry, according to the Centers for Disease Control and Prevention (CDC).

"The most important thing here is washing your hands,” says Reynolds. “Don't worry too much about the soap.”