Unlike the herb you cook with, commercially-prepared oregano oil is highly concentrated and should be diluted before use. Side effects can include nausea and vomiting. Oregano essential oil is made ...

Oil of oregano, also referred to as oregano oil, is pretty much what it sounds like: a concentrated extract from the leaves of an oregano plant. "While oil of oregano can be part of a short-term ...

It comes from leaves of the oregano plant. You may be familiar with oregano's use in cooking. It's also been used in traditional folk or herbal medicine for centuries to treat or prevent illnesses.