There are many species of oregano, the perennial shrub found in the Mediterranean. Common culinary forms are "Italian" and "Greek" often drunk as a tea for medical purposes as an anti-parasitic ("worms").
Bu there's one form, the so called "medicinal" oregano that's only used for therapeutic purposes. It has the highest amount of carvacrol and is usually purchased as an oil which is always diluted with another oil, usually olive oil. Pure carvacrol is far far too powerful to be anywhere near the human body by itself and even the oil you buy needs to be cut 1:10 before it can be applied to skin.
Oregano oil is anti-bacterial, anti-viral and anti fungal and appears to have anti-inflammatory effects.