Tea Tree essential oil is likely the single most effective antibacterial and anti-fungal essential oil. Tea tree is one of the few oils that can safely be applied directly to the skin without dilution to treat acute issues. That said, it may be best to start with a dilution if you aren't sure. Tea tree essential oil is said to be highly beneficial for all types of infection, burns, wounds, insect bites, and stings. Antiviral properties also assist the healing of cold sores, as well as cold and flu. It is also useful for various skin conditions such as acne, rashes, and dandruff. Tea tree is poisonous if ingested, so please store this in a safe place where pets and children can not accidentally ingest it. It also is generally not suitable for use on pets.