According to the National Institute of Health, oregano oil is known to have antimicrobial, antifungal, antitumor and antiparasitic benefits. The active constituents of oregano oil are carvacrol, thymol and borneol volatile oils, flavonoids, rosmarinic acid, triterpenoids, sterols and vitamins A and C. These elements work together to provide a double dose of benefits. Oregano is considered safe, but there are precautions for use of the oregano oil.


The University of Minnesota notes that no essential oils should be taken internally and caution is given about possible toxic effects if ingested, especially by children. In addition, there may be potentially harmful drug interactions between medications and oils. Oregano oil, as a highly concentrated oil, may irritate the skin and mucous membranes. It is not recommended for massages or for use on sensitive skin. Due to the concentrated nature and lack of research on oregano oil’s side effects, the oil of oregano should be used only as recommended by a professional and in diluted concentrations. The University of Michigan Health Center also suggests that it is contraindicated in pregnancy and may cause harm to a baby.

Antimicrobial Benefit

Ege University performed a study to test the effectiveness of oregano oil against the bacterium Salmonella typhimurium. Salmonella, when ingested, can cause nausea, abdominal pain, cramps and diarrhea. The study concluded that oregano oil might be a viable alternative to chlorine use for decontaminating lettuce. Another study published in the Journal of Food Protection concluded that the components of thymol and carvacol in oregano oil inhibited the growth of Clostridium perfringens, which causes food poisoning. Oregano oil use along with other safety measures may optimize or enhance microbiological food safety.

Antifungal Benefit

Test tube experiments have indicated that oregano oil has antifungal properties and is more effective than a commonly used antifungal agent, calcium magnesium caprylte against Candida albicans. Candidiasis is a yeast infection. Clinical studies have not been done to confirm comparable results in humans.

Antiparasitic Benefits

Research published in Parasitology Research Journal in 2006 documented experiments using oregano essential oils. In these experiments, oregano oil induced lysis of Trypanosoma cruzi. Trypanosoma cruzi are parasites that can infect humans and cause Trypanosomiasis or Chaga’s Disease. The presence of thymol in the oregano oil is considered to be the source of the antiparasitic benefit.

Antitumor Benefits

The Oral Roberts University Biology Department is conducting research using carvacrol—a key component of oregano oil—to combat tumors and malignant cells. Preliminary results indicate that carvacrol may induce cell self-destruction. The department is focusing its research on human liver cancer cells. Another constituent of oregano oil, quercetin, is being tested on ovarian and breast cancers.