Does soap kill germs?

Dear Alice,

I remember reading somewhere a couple years ago that hand or bath soap does not KILL germs or sterilize our hands. Rather, it helps loosen dirt and grime, and it makes the skin more slippery so that dirt and germs rinse off more easily with water. It makes sense to me, but my daughter who is studying for a medical career said I was off my rocker. I am getting older, but I'm sure I didn't fall out of my chair onto my head — but instead read that in a health newsletter somewhere. What's the skinny? Can my daughter trust me and what I read (in this case, at least), or should I throw in the towel (for 100 percent memory recall)?

— Slippery Soap

Dear Slippery Soap, 

You deserve a high five for asking about a crucial illness-fighting habit! To answer your question, you’re correct about how the average hand soap works, but you and your daughter may have been talking about two slightly different versions of the sudsy stuff. Regular household soap and antimicrobial/antibacterial soap work in different ways to get your hands squeaky clean. The appropriate use of either one may depend on where you’ll be washing your hands and what you’ll be doing with them once they’re clean. And, when it comes to liquid versus bar soap, there is a preferred choice to further avoid germs when you lather up your phalanges (more on that in a bit).

Regular household soap or cleanser does not kill germs (as you correctly asserted) — rather, it suspends (or lifts) them off the skin surface, allowing the microbes and soil bits to be rinsed down the drain. This explains why it’s more effective to use soap when washing hands, rather than just relying exclusively on warm water. Additionally, people tend to scrub their hands more thoroughly when using soap, which further removes germs.

Antimicrobial or antibacterial soap, on the other hand (pun intended!), does kill bacteria and other microorganisms, and can sometimes inhibit their future growth. This is likely what your daughter will use before she performs patient exams. Although antibacterial soap has been available for home use, there’s no significant evidence to suggest that these cleansers are more effective than plain soap for preventing infection under most circumstances in the home or in public spaces. There’s also not enough known about the safety of using antibacterial soaps in the long-term; one concern is the possibility that using antibacterial soap may contribute to the growing problem of antibiotic drug resistance. Drawing from these concerns, the U.S. Food and Drug Administration (FDA) recently issued a final ruling that bans the inclusion of several antibacterial ingredients in consumer soaps that are used with water (including the gel, liquid, bar, and foam varieties — the ban doesn’t restrict these ingredients in hand sanitizers or hand wipes at this time). Furthermore, when it comes to lowering the risk for spreading infection, the Centers for Disease Control and Prevention (CDC) suggest that regular soap is adequate for the general public, and that antibacterial soaps can be saved for those working in health care, child care, or food preparation settings.

Another worthy distinction to make when it comes to getting sudsy relates to the form of soap you use. Bar soap, unfortunately, can harbor germs and enable the spread of germs between individuals. Liquid hand soap is both easy to use and resists the spread of germs from one individual to another. It also often contains moisturizing agents that keep your skin from becoming dry, even after frequent washes.

Regardless of the type of soap used, proper and adequate hand washing is key to hand hygiene and is considered the best way to prevent the transmission of microorganisms. For more dirt on getting your digits clean check out the related questions.

Last updated Sep 16, 2016
Originally published May 04, 2001

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