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Oil of oregano, also known as oregano extract or oregano oil, can be consumed orally as a supplement. It’s important to note that it is different from oregano essential oil. 

Oregano essential oil, which is made by steaming and distilling dried oregano leaves, is meant to be diffused or mixed with a carrier oil and applied topically. But it should not be eaten on its own. Essential oils are very potent, and ingesting them in an unencapsulated form can damage the intestinal lining. 

You can read more about how to safely use essential oils here, but the remainder of this article will focus on oregano oil that can be taken orally as a supplement.

The beneficial components in oregano oil change depending on how the extraction is done and where the oregano was grown, says Melissa Majumdar, a dietitian and spokesperson for the Academy of Nutrition and Dietetics.

However, here are some of the most common components you’ll find in oregano oil: 

• Luteolin 7-O-glocoside, a flavonoid and antioxidant with anti-inflammatory properties and possible cardiovascular benefits3, according to preclinical research.
• A compound found in herbs, rosmarinic acid has been found in preclinical literature to be antiviral, antibacterial, and anti-inflammatory1. Human studies have found beneficial effects, but more research is needed.
• Thymol, a compound with antibacterial, antifungal, and antibacterial activity, is currently being investigated for its role in treating respiratory, nervous, and cardiovascular systems disorders4.
• Carvacrol is an abundant phenolic compound in oregano with antioxidant and antimicrobial activity. It works by damaging the harmful bacteria’s cell wall5, causing the cellular components to leak out.

The potential benefits of oregano oil range from acne and asthma to psoriasis and wound healing.

In traditional medicine6, oregano was used for respiratory conditions, like bronchitis or a cough, diarrhea, inflammation, and menstrual disorders. However, scientific literature has not caught up to support these uses in humans. 

Here is some of the preliminary research on oregano oil along with its potential benefits:

1.

It promotes a healthy gut microbiome.

Oregano oil has been shown to have antimicrobial properties in preliminary research. In one study, oregano oil showed significant antibacterial activity10 against 11 microbes that were resistant to multiple antibiotics. Both carvacrol and thymol have also been studied to work with antibiotics5 to overcome resistant bacteria. 

For its antibacterial effects, functional nutrition expert English Goldsborough, FNTP, often recommends oregano oil to clients who are battling mold exposure, a sinus infection, or a cough or sore throat.

Inflammation is a driving factor for a variety of conditions12, including arthritis, psoriasis, cancer, and Type 1 diabetes. Antioxidants found in oregano oil can combat inflammation and potentially help mitigate related diseases. 

Lab studies13 have shown that pretreating cells with oregano extract resulted in a protective effect against oxidative stress—the oxygen-dependent process that drives inflammation. 

In mice, the anti-inflammatory effects of oregano extract prevented14 animals predisposed to Type 1 diabetes—an autoimmune inflammatory disorder—from developing the disease. 

Oregano’s ability to temper inflammation shows promise in cancer treatment studies. In another mouse-model study15, oregano suppressed tumor growth and appearance. And in human breast cancer cells16, the oregano species with the most antioxidant activity significantly reduced cancer cell proliferation. 

Does oregano oil boost brain health? According to one study17, oregano extract can elevate mood and have an anti-depressive effect in animals.

In rats, two weeks of consuming low doses of carvacrol increased serotonin and dopamine18 levels, which suggests it could improve feelings of well-being. In a separate study, oregano extract fed to rats increased the expression of genes related to cognitive function and memory even when the rats were under chronic stress. But again, these are preclinical animal studies, so more research in humans is needed.

Oregano leaf is “likely safe” in the quantities commonly occurring in foods, but oil of oregano supplements are possibly unsafe for pregnant and breastfeeding women, according to the National Library of Medicine.

Large doses of oregano might also increase risk of bleeding and therefore are unsafe for surgery patients. If you’re scheduled for surgery, stop all oregano oil supplementation at least two weeks before. 

Oregano oil can also interact with diabetes medications and blood thinners. So, it’s important to talk to your health care provider before you add oregano oil (and any supplement) to your routine.

Oregano oil may also cause gastrointestinal upset and rash in some people, Majumdar says. If this happens to you, it’s best to stop and try an alternative.