Tea tree oil (TTO) is extracted from the Melaleuca alternifolia and in the past decade has become a popular topical antimicrobial for skin conditions such as tinea pedis and acne. The three major components of TTO responsible for anti-P. acnes activity have been found to be alpha-terpineol < terpinen-4-ol < alpha-pinene (listed in order or increased minimum inhibitory concentration (MIC) values) (60). Besides its anti-P. acnes properties, TTO has been found to have a significant and rapid (within 10 minutes) anti-inflammatory activity when applied to histamine-induced weals (61). This could be an additional pathway through which TTO improves inflammatory acne.
One of the few clinical studies conducted in acne compared a 5% TTO gel with a 5% benzoyl peroxide lotion in 124 acne patients. Both treatments had a significant effect in improving both inflamed and non-inflamed acne lesions, although benzoyl peroxide produced faster results. Fewer side effects, though, were experienced in the TTO group (62).