Skin washes containing 5% tea tree oil are more effective than regular soap at killing infectious bacteria on the skin, according to researchers at the School of Biomedical and Chemical Sciences at the University of Western Australia.

The finding may have particular relevance in healthcare settings, where proper hand washing plays a critical role in preventing the spread of infection. Studies have shown, however, that less than half of healthcare workers wash their hands as frequently and for as long as is recommended. Frequent hand washing can irritate the skin, especially when harsh cleansers are used. While tea tree oil has shown antibacterial, antiviral and antifungal properties in numerous studies, it does not appear to damage skin and may even spare normal skin bacteria.

The current study looked at the effectiveness of antiseptic skin washes containing tea tree oil on 27 people. Two groups did hand-washing trials with either a hygienic skin wash with 5% tea tree oil, a skin wash with 5% tea tree oil in a solution of Tween 80 (a mild detergent that dissolves oils and fats), an alcoholic hygienic skin wash with 5% tea tree oil, or regular soft soap.

Researchers found that the amount of bacteria on the hands after dipping them in a contaminated fluid was less after washing with each of the three tea tree oil preparations than after using regular soft soap. The difference was not statistically significant for hygienic skin wash with tea tree oil, however. The results suggest that some skin washes with 5% tea tree oil clear bacteria from the skin more effectively than regular soap.

Journal of Hospital Infection 2005;59:220–8