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Research · Supplements

Oregano oil

Controlled human research on oregano oil taken by mouth was not located. An uncontrolled study of 14 adults found fewer gut parasites after 6 weeks. A mixed herbal throat spray eased symptoms at 20 minutes but not at 3 days. An oregano ointment lowered wound bacteria. Systemic allergic reactions to eating oregano have been reported.

Add to Bio HackChecked 2026-11-09
Status
Sold as a dietary supplement and essential oil in the US.
Also called
oil of oregano, oregano essential oil, Origanum vulgare, Mediterranean oregano, wild oregano oil, carvacrol, thymol, P73
Taken for
natural antibiotic, infections, colds, sore throat, candida, gut parasites, SIBO, immunity, wound healing, asthma

Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on

Shown to help4

Reported risks1

What people take it for, and what was found

Shown to help4

Limited

Gut parasites

Limited evidence: in 14 adults with no control group, gut parasites cleared in some after 6 weeks of emulsified oregano oil.

The numbers and sources
Effect
In 14 adults with parasites in their stool, 600 mg a day of emulsified oregano oil for 6 weeks was followed by complete disappearance of Entamoeba hartmanni in 4 cases, Endolimax nana in 1 and Blastocystis hominis in 8. Gut symptoms improved in 7 of 11 people with Blastocystis [1].
Population
14 adults, no control group [1].
Sources
[1]
Caveats
Without a control group, natural clearance cannot be ruled out.
Limited

Colds and sore throat

One trial found a five-oil spray including oregano eased the worst cold symptom more than placebo at 20 minutes, with no difference after 3 days.

The numbers and sources
Effect
In 60 primary care patients with upper respiratory infections, a spray of five essential oils, including Origanum syriacum, used 5 times a day eased the worst symptom more than placebo 20 minutes after use (p 0.019). After 3 days, the groups did not differ significantly [2].
Population
26 patients on the spray and 34 on placebo, in Israel [2].
Sources
[2]
Caveats
The spray combined five plant oils, so the result cannot be assigned to oregano [2].
Limited

Wound healing on the skin

One trial found fewer staph bacteria in wound cultures with a topical oregano ointment than petrolatum after skin surgery, with similar scars.

The numbers and sources
Effect
In 40 patients after skin surgery, 3% oregano extract ointment was followed by Staphylococcus aureus in 19% of wound cultures, against 41% with petrolatum. One patient on oregano and 3 on petrolatum developed cellulitis. Overall scar appearance was equivalent, with better scar color, pigmentation and pliability on oregano [3].
Population
40 patients after surgical excision [3].
Sources
[3]
Caveats
A topical extract, not an oral oil. One small trial.
Limited

Asthma (carvacrol)

One small trial found better lung function and fewer symptoms from baseline on carvacrol, an oregano compound, in adults with asthma.

The numbers and sources
Effect
In 23 adults with asthma, carvacrol capsules at 1.2 mg/kg a day for 2 months raised lung function test values and reduced most respiratory symptoms, white cells and hs-CRP. The placebo group did not change [4].
Population
12 on carvacrol and 11 on placebo, in Iran [4].
Sources
[4]
Caveats
Carvacrol is one compound in oregano oil. The abstract compares each group with its own baseline [4].

Claimed, not studied in people1

Untested

Infections and candida treated by mouth

Not studied in people. Mice with a body-wide candida infection survived more often when fed oregano oil, and in the lab it stopped candida growth.

No study in people. This rests on animal studies, lab studies.

The numbers and sources
Effect
In culture, oregano oil at 0.25 mg/mL completely inhibited Candida albicans growth. In mice with systemic candidiasis, oregano oil given by mouth daily for 30 days was followed by 80% survival with no candida in the kidneys, while mice fed olive oil alone died within 10 days [7]. A 2025 systematic review of lab studies of four oregano species found antifungal activity against Candida, Aspergillus and Penicillium species, linked to carvacrol, thymol and related compounds [8].
Population
Mice, 6 per group, and Candida albicans cultures [7]. Lab studies of fungal strains [8].
Sources
[7], [8]
Caveats
One small mouse study and lab work. Results in culture do not show what happens in the body. No trial of oral oregano oil for candida or other infections in people was located.

Doses studied

The parasite study used 600 mg a day of emulsified oil for 6 weeks [1]. The wound trial used a 3% extract ointment [3]. Carvacrol trials used 1 to 2 mg/kg a day for 1 to 2 months [4][5].

Risks

Reported risks1

Limited

Allergic reactions

Case reports: one person had three systemic allergic reactions after eating oregano and thyme.

The numbers and sources
Effect
One patient had three systemic allergic reactions after eating oregano and thyme. Skin and IgE tests were positive to several plants of the mint family, and negative in 10 control patients [6].
Population
Single case report with controls for testing [6].
Sources
[6]
Caveats
A case report of the herb in food, not the concentrated oil.

Checked, no increase found1

Limited

Blood and urine tests with carvacrol

One small study found no overall change in routine blood or urine tests in healthy adults taking carvacrol for a month.

The numbers and sources
Effect
In healthy adults given 1 or 2 mg/kg a day of carvacrol for a month, routine blood tests, urine tests and spirometry did not change significantly overall. At 1 mg/kg, calcium, hemoglobin and hematocrit fell and creatine phosphokinase rose compared with baseline [5].
Population
Healthy adults in a phase I study. The abstract does not give the number [5].
Sources
[5]
Caveats
Carvacrol alone, not the whole oil. No long-term human safety data were located.

Sources

  1. Force M, Sparks WS, Ronzio RA. Inhibition of enteric parasites by emulsified oil of oregano in vivo. Phytotherapy Research. 2000. https://doi.org/10.1002/(sici)1099-1573(200005)14:3<213::aid-ptr583>3.0.co;2-u
  2. Ben-Arye E, Dudai N, Eini A, et al. Treatment of Upper Respiratory Tract Infections in Primary Care: A Randomized Study Using Aromatic Herbs. Evidence-Based Complementary and Alternative Medicine. 2011. https://doi.org/10.1155/2011/690346
  3. Ragi J, Pappert A, Rao B, et al. Oregano extract ointment for wound healing: a randomized, double-blind, petrolatum-controlled study evaluating efficacy. Journal of Drugs in Dermatology. 2011. https://pubmed.ncbi.nlm.nih.gov/21968667/
  4. Alavinezhad A, Khazdair MR, Boskabady MH. Possible therapeutic effect of carvacrol on asthmatic patients: A randomized, double blind, placebo-controlled, Phase II clinical trial. Phytotherapy Research. 2018. https://doi.org/10.1002/ptr.5967
  5. Ghorani V, Alavinezhad A, Rajabi O, et al. Safety and tolerability of carvacrol in healthy subjects: a phase I clinical study. Drug and Chemical Toxicology. 2021. https://doi.org/10.1080/01480545.2018.1538233
  6. Benito M, Jorro G, Morales C, et al. Labiatae Allergy: Systemic Reactions Due to Ingestion of Oregano and Thyme. Annals of Allergy, Asthma & Immunology. 1996. https://doi.org/10.1016/s1081-1206(10)63456-4
  7. Manohar V, Ingram C, Gray J, et al. Antifungal activities of origanum oil against Candida albicans. Molecular and Cellular Biochemistry. 2001. https://doi.org/10.1023/a:1013311632207
  8. Mezzomo L, Butzge J, Fiorio M, et al. Origanum Essential Oil and Antifungal Activity: A Systematic Review. Chemistry & Biodiversity. 2025. https://doi.org/10.1002/cbdv.202402296

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