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Can Soap Really Kill Germs?

Posted Apr 12 2012 2:01am

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Mitte must know…I often get contact dermatitis on my hands from soaps (liquid, soapbars or even the “mild” ones). I understand a good hygiene is necessary to prevent spreading of bacteria and virus, but how effective is really soap (surfectants) when it comes to killing germs in the first place? Is there an effective alternative that is not so irritating/dehydrating? In other words, what surfectant is the mildest on the market and does it work on germs?

The Left Brain responds:

A quick literature review, courtesy of PubMed, should help answer your question.

According to a research paper entitled “The effect of handwashing with water or soap on bacterial contamination of hands” water alone won’t cut it (at least not for bacteria of faecal origin.)  The researchers found that not washing hands resulted in a 44% contamination rate. Washing with water alone dropped the contamination level to 23% and washing with non-antibacterial soap showed only 8% contamination. So clearly, even regular soap is much better than rinsing with water alone.  (Ref. 1)

Okay, so you do need to use soap to control bacteria. But do you need special antibacterial soap? Another study  found that that “although differences in efficacy between antimicrobial and nonantimicrobial soap were small, antimicrobial soap produced consistently statistically significantly greater reductions” (Ref. 2) When it comes to keeping your hands free from bacteria it looks like soap is a MUST have and antibacterial soap is a NICE to have.

If surfactant mildness is your concern, look for a hand soap (ok, actually it’s detergent, not soap) based on an ingredient called “Sodium Cocoyl Isthionate (or SCI for short). This is one of (if not the) mildest surfactant on the market. We’ve blogged before how it’s used in the mildest body washes and shampoos. You can use hand santiziers but those are often alcohol based and they may be drying to your skin.


1. Int J Environ Res Public Health. 2011 Jan;8(1):97-104. Epub 2011 Jan 6. The effect of handwashing with water or soap on bacterial contamination of hands.

2. J Food Prot. 2011 Nov;74(11):1875-82. A meta-analysis of the published literature on the effectiveness of antimicrobial soaps.

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