Oregano
 
Oregano is one of the most potent and powerful essential oils and has been used for centuries in traditional practices. The primary chemical components of Oregano is carvacrol. Due to its high phenol content, caution should be taken when inhaling or diffusing Oregano; only one to two drops is needed. 

Oregano is a popular cooking spice and Oregano essential oil is an ideal substitute in recipes.