Tea tree oil is an essential oil extracted from the Melaleuca alternifolia plant, native to Australia. Tea tree leaf oil is known to have antibacterial qualities, the mechanism for this is not completely understood, but research shows that it could be due to an ability to damage the bacterial cell wall.

It also has anti-inflammatory effects, due to its content of terpen-4-ol, which studies have shown reduces inflammation in the skin when applied topically. These functions make it a great ingredient for the use in acne treatments, both to kill p.acnes bacteria, but also reduce the associated inflammation.