Oil of oregano is not oregano essential oil. It does not need to be diluted and can be taken internally. It is oregano that has been macerated in olive oil for a few 6-8 weeks. oregano is considered a "cure-all" plant. Because of the strong oils in oregano it is a strong antiseptic and anti-bacterial. oli of oregano is also grerat for stumach aches and indigestion. The oil can easily be applied under the tongue. It also helps to fight off colds and flus and other viruses.