Tea tree oil can lead to antibiotic resistance

Feb 18 2007

Repeated exposure to low doses of Tea Tree Oil - a common ingredient in many beauty products - can increase the chances of suffering from "superbug" infections, University of Ulster scientists have revealed.

They discovered that exposure to low doses of Tea Tree Oil make pathogens such as MRSA, E. coli and Salmonella more resistant to antibiotics, and capable of causing more serious infections.

Dr Ann McMahon and Professor David McDowell, members of the University's Food Microbiology Research Group, said: "We have been growing pathogens such as MRSA, E-coli and Salmonella in low concentrations of tea tree oil. These concentrations are not sufficient to kill the bacteria, but can switch on their defense mechanisms. Unfortunately, these defense mechanisms have the added effect of making bacteria more resistant to antibiotics, and able to cause "harder to treat" infections."

Tea Tree Oil is used commercially in many products including shampoos, body lotions and toiletries, but there is no legislation requiring manufacturers to state the concentration of tea tree oil in these products. This increases the risks that people will use low concentrations of tea tree oil, which fail to kill bacteria, but increase their resistance to antibiotics. So, if a person uses tea tree oil products on their skin repeatedly, any MRSA on their skin could develop increased resistance to the antibiotics which are used to control MRSA infections.

"The bottom line is that tea tree oil should not be used at low concentrations - less than 4% - to make sure that bacteria are killed, not just stressed. Otherwise we are just arming the bacteria against treatment by antibiotics."

Publishing their findings in the Journal of Antimicrobial Chemotherapy, the scientists said: "Although tea tree oil may be an effective antimicrobial agent when appropriately used at high (bactericidal) concentrations, its application at low (sub-lethal) concentrations may contribute to the development of antibiotic resistance in human pathogens".