Oregano Oil
Oregano oil (Origanum vulgare): what the claims are, what human research exists, how oil of oregano supplements differ from the essential oil, and safety points.
Content last updated . This page has not been medically reviewed.
Safety first. Supplements can cause side effects and interact with medicines. Read mushroom safety and interactions before you use any mushroom product.
Safety first. Oregano oil is a concentrated essential oil. Poison Control says misuse of essential oils can cause serious poisoning, that many can cause rashes on skin, and that some are poisonous if absorbed through the skin or swallowed. [1] We do not advise swallowing the essential oil or putting it in the mouth. If someone may have swallowed any essential oil, call Poison Help at 1-800-222-1222 (US); call 911 for collapse, a seizure or trouble breathing. [1] See Poisoning: what to do first.
The claim, as marketed
Oregano oil is often promoted online as a natural antibiotic or immune helper. This page checks what the sources we read actually show. It separates three things that share the name: the essential oil, "oil of oregano" products sold as supplements, and oregano as a kitchen herb.Which plant, which part
The accepted name on GBIF is Origanum vulgare L., in the mint family (Lamiaceae). [2] LactMed (the US National Library of Medicine's drug and lactation database) says oregano leaves and oil contain carvacrol, thymol, eugenol and rosmarinic acid. [3] Oregano as a herb is covered in Oregano (herbs and botanicals). Poison Control cautions that for essential oil products in general it can be hard to know what species of plant, what concentration of active ingredient or what contaminants are in the bottle. [1] The sources we read do not say how often "oregano" oils are other species.Traditional use
Traditional use only, not proof. LactMed says oregano has been used in medicinal amounts for respiratory and digestive disorders and as an antimicrobial, and has been used as a galactogogue (to support milk supply) in Türkiye. [3] Poison Control says many essential oils have a long history of medicinal use based largely on traditional practices and folklore, and few uses have been studied scientifically. [1]What research shows
| Question | What the source found | Strength of evidence | Population and form studied |
|---|---|---|---|
| Does oregano oil treat infections in people? | A 2021 study of 106 people with metabolic syndrome compared Origanum vulgare essential oil with antibiotic treatment for minor infections over 10 days; the authors reported an antibacterial effect similar to the antibiotic and no intestinal side effects. [4] | Promising but limited; one small study | 106 adults with metabolic syndrome; the abstract does not give the route or preparation, so it cannot be applied to a product [4] |
| Carvacrol (the main chemical) in people | A 2018 review said that human trials on carvacrol are still lacking, which impedes conclusions of clinical relevance. [5] | Preclinical (cells or animals) | Laboratory and animal work [5] |
| Candida infection, nipple infection while breastfeeding | LactMed says oregano oil has been advocated for nipple Candida infection but no clinical studies have confirmed the safety or efficacy of that use. [3] | Marketing claim; insufficient evidence | Not applicable |
| Colds, cancer, gut health, "immune boosting" | Proper evidence not found. We searched PubMed for oregano oil and oregano essential oil trials in people and read LactMed and Poison Control. | Insufficient evidence | Not applicable |
Laboratory studies show oregano oil can affect microbes in a dish. That is not evidence that it works in the body, and it does not show a product is safe. See Essential oils: human versus lab research. Infections need a clinician; skipping medical care for a serious infection can be dangerous.
Essential oil versus "oil of oregano" supplements
The essential oil is the concentrated plant oil. Products sold as "oil of oregano" may be diluted in another oil or put in capsules; the sources we read do not describe how such products differ from one another. LactMed notes that dietary supplements may contain multiple ingredients, that labeled and actual ingredients or amounts often differ, and that results on one product may not apply to another. [3] Poison Control notes that essential oil products are not well regulated and that makers are not always required to show they work. [1] For quality checks see quality testing and certifications and reading an essential oil label.Official statements
- LactMed (US National Library of Medicine): oregano and oregano oil are "generally recognized as safe" by the FDA as food ingredients. [3] That is a food-ingredient status, not an approval of the oil as a treatment.
Frequently asked questions
Is oregano oil a natural antibiotic?
Not shown. One small study in people with metabolic syndrome suggested an antibacterial effect, but the abstract does not give the preparation. [4] A review said human trials on carvacrol are lacking. [5]
Is oil of oregano the same as oregano essential oil?
The names are used for different products, and the sources we read do not define them. Labeled and actual contents of supplements often differ. [3]
Is oregano oil safe to swallow?
We do not advise swallowing any essential oil. Poison Control warns that misuse can cause serious poisoning. [1]
Can oregano oil burn or irritate skin?
Poison Control says many essential oils can cause rashes. [1] Oregano-specific burn data were not found in the sources we read.
Is oregano oil safe while breastfeeding?
No data exist, according to LactMed. [3] Ask a clinician.
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Safety
- Skin. The sources we read give no oregano-specific skin data. LactMed says allergic skin reactions have been reported rarely. [3] Poison Control says diluting essential oils in a carrier oil is the best way to avoid a bad reaction, and not to use them on damaged skin. [1] See strong oils and skin reactions.
- Swallowing. LactMed says oregano is generally well tolerated, with rare stomach upset, but that refers to oregano as a food flavoring and supplement, not to swallowing essential oil. [3] Poison Control warns that aspirating (breathing in) a swallowed oil can cause pneumonia. [1]
- Children. Poison Control says children have thin skin and immature livers, which might make them more susceptible to toxic effects. [1]
- Breastfeeding. LactMed says no data exist on safety or efficacy in nursing mothers or infants, and that amounts higher than those used as a food flavoring should probably be avoided during breastfeeding. [3] See pregnancy and breastfeeding. Pregnancy safety of the oil is not described in the sources we read.
- Medicines. Poison Control says essential oils may interact with medications; oregano-specific interactions are not described in the sources we read. [1] See how interactions work.
- Surgery: tell the surgical team about any oil or supplement.
References
- Essential oils: Poisonous when misused (Poison Control). Read 2026-10-23.
- Origanum vulgare L. (GBIF Backbone Taxonomy). Read 2026-10-23.
- Oregano (Drugs and Lactation Database, LactMed, National Library of Medicine). Read 2026-10-23.
- The Antimicrobial Activity of Origanum vulgare L. Correlated with the Gastrointestinal Perturbation in Patients with Metabolic Syndrome. Molecules 2021. Read 2026-10-23.
- Carvacrol and human health: A comprehensive review. Phytother Res 2018. Read 2026-10-23.