With Antibiotic-Resistant Bacteria on the Rise, Study Confirms Risks of Antibacterial Soaps


(Beyond Pesticides, October 18, 2007)

Antibacterial soaps show no health benefits over plain soaps and, in fact, may render some common antibiotics less effective, says University of Michigan public health professor Allison Aiello, Ph.D. The study, “Consumer Antibacterial Soaps: Effective or Just Risky?” appears in the August edition of Clinical Infectious Diseases.

In the first known comprehensive analysis of whether antibacterial soaps containing triclosan work better than plain soaps, Dr. Aiello of the University of Michigan School of Public Health and her team found that washing hands with an antibacterial soap was no more effective in preventing infectious illness than plain soap. Moreover, antibacterial soaps at formulations sold to the public do not remove any more bacteria from the hands during washing than plain soaps.

Because of the way triclosan, the main active ingredient in many antibacterial soaps, reacts in the cells, it may cause some bacteria to become resistant to commonly used drugs such as amoxicillin, the researchers say. These changes have not been detected at the population level, but e-coli bacteria bugs adapted in lab experiments showed resistance when exposed to as much as 0.1 percent weight/volume triclosan soap.

“What we are saying is that these e-coli could survive in the concentrations that we use in our (consumer formulated) antibacterial soaps,” Dr. Aiello said. “What it means for consumers is that we need to be aware of what’s in the products. The soaps containing triclosan used in the community setting are no more effective than plain soap at preventing infectious illness symptoms, as well as reducing bacteria on the hands.”

The University of Michigan team looked at 27 studies conducted between 1980 and 2006, and found that soaps containing triclosan within the range of concentrations commonly used in the community setting (0.1 to 0.45 percent wt/vol) were no more effective than plain soaps. Triclosan is used in higher concentrations in hospitals and other clinical settings, and may be more effective at reducing illness and bacteria in the hospital setting, according to the researchers.

With the rise of antibiotic-resistant bacteria responsible for an increasing number of hospitalizations, deaths and school closures, public health advocates are concerned over the rampant overuse of antimicrobial products and antibiotics. Triclosan is found in hundreds of common everyday products, including nearly half of all commercial soaps. In addition to soaps, triclosan is found in deodorants, toothpastes, cosmetics, fabrics and plastics.

Triclosan works by targeting a biochemical pathway in the bacteria that allows the bacteria to keep its cell wall intact. Because of the way triclosan kills the bacteria, mutations can happen at the targeted site. Dr. Aiello says a mutation could mean that the triclosan can no longer get to the target site to kill the bacteria because the bacteria and the pathway have changed form.

The analysis concludes that government regulators should evaluate antibacterial product claims and advertising, and further studies are encouraged. The FDA does not formally regulate the levels of triclosan used in consumer products. Other antiseptic products on the market contain different active ingredients, such as the alcohol in hand sanitizers or the bleach in some antibacterial household cleaners. Dr. Aiello’s team did not study those products and those ingredients are not at issue.

Additionally, researchers at Virginia Tech have found that triclosan reacts with chlorine in tap water to form significant quantities of chloroform. Chloroform is classified by the Environmental Protection Agency (EPA) as a probable human carcinogen. The research also suggests that the reaction of triclosan with chlorine could produce highly chlorinated, and thus dangerous, dioxins in the presence of sunlight.


When used in hospitals and other health care settings, or for persons with weakened immune systems, triclosan represents an important health care and sanitary tool. Outside of these settings, it is totally unnecessary, and the constant exposure to triclosan becomes a health and environmental hazard. The best solution to preventing infections is good old soap and water. Make sure you read all labels when buying soaps and other toiletry products to ensure that triclosan is not included. Also be on the lookout for Microban and Irgasan, which are other names for triclosan. Consult our Triclosan factsheet for a list of products containing triclosan (some, like Teva sandals and kitchen knives, may surprise you) and for more detailed information on alternatives to triclosan.