Oregano was used extensively by the Greeks for conditions ranging from convulsions to a variety of other conditions. Nineteenth-century American Eclectic physicians employed oregano as both a tonic and to promote menstruation.

Oregano contains several constituents, including volatile oils such as carvacrol, thymol, and borneol, plus flavonoids, rosmarinic acid, triterpenoids, sterols, vitamin A, and vitamin C.

The thymol and carvacrol contents in oregano are responsible for promoting its antimicrobial and antifungal effects. A test tube study demonstrated the oil, carvacrol in particular, inhibited the growth of Candida albicans far more effectively than a commonly employed antifungal agent called calcium and magnesium caprylate.

In addition to its anti-fungal activity, and according to results from another study in Australia, oregano oil promotes anti-microbial activity against a wide number of bacteria.

Oregano oil should always be taken with caution and one must not exceed the recommendations.