The use of citrus oils dates back to as far as 800BC, although its benefits are not as widely known as you may think. These oils are used to help disinfect, and also dissolve other oils (excess skin oils) and are proven to be toxic to several strains of bacteria and fungi commonly found on the skin.
Lemon is known for its ability to clean toxins from any part of the body, including the hair and scalp. They contain anti oxidant molecules and an anti inflammatory compound, one of the reasons why citrus oils are often included in acne treatments.