Oregano Oil
Research reviewed: Up until 03/2026
Oregano Oil (Origanum vulgare (essential oil)) is a dietary supplement with 7 published peer-reviewed studies involving 264 participants, researched for Antimicrobial & SIBO, Gut Health, Antioxidant & Anti-inflammatory.
Evidence at a Glance
Strength is scored by study design, sample size, study type, and outcomes
Antimicrobial & SIBO
ModerateGut Health
ModerateAntioxidant & Anti-inflammatory
ModerateResearch Visualised
Visual breakdown of the clinical data.
Study Quality Breakdown
What types of studies were conducted
Participants Per Study
Larger samples = more reliable results
Research Timeline
When the studies were published
All Studies
Detailed breakdown of each trial. Click to expand.
Antimicrobial & SIBO
To evaluate emulsified oregano oil for eradication of enteric parasites.
Study Type
Prospective clinical study
Purpose
To evaluate emulsified oregano oil for eradication of enteric parasites.
Dose
600 mg emulsified oregano oil daily
Participants
14 patients with enteric parasites
Duration
6 weeks
Results
Enteric parasites were completely eradicated in 8 of 14 patients (57%). Blastocystis hominis was eliminated in 8 of 11 positive patients. GI symptoms improved in all.
How They Measured It
Stool microscopy for parasites (Entamoeba, Blastocystis, Endolimax)
To evaluate herbal therapies (including oregano oil) vs rifaximin for SIBO.
Study Type
Retrospective clinical study
Purpose
To evaluate herbal therapies (including oregano oil) vs rifaximin for SIBO.
Dose
Oregano oil 200 mg twice daily (as part of herbal protocol)
Participants
104 SIBO patients (herbal arm: 57, rifaximin arm: 47)
Duration
4 weeks
Results
Herbal therapy (including oregano oil) showed 46% breath test normalization rate vs 34% for rifaximin (p=0.24). Herbal therapy was non-inferior and used as rescue after rifaximin failure.
How They Measured It
Lactulose breath test normalization rate
To evaluate antimicrobial activity of oregano oil (carvacrol, thymol) against GI pathogens.
Study Type
In vitro study
Purpose
To evaluate antimicrobial activity of oregano oil (carvacrol, thymol) against GI pathogens.
Dose
Various concentrations of oregano oil and isolated carvacrol
Participants
In vitro (panel of GI pathogens)
Duration
N/A
Results
Oregano oil showed potent activity against all tested pathogens. Carvacrol was identified as primary active component. MIC against H. pylori: 0.1-0.5 μg/mL.
How They Measured It
MIC and MBC against H. pylori, C. difficile, E. coli, Candida spp.
Gut Health
To evaluate oregano oil supplementation on gut symptoms and microbiome.
Study Type
Randomised, double-blind, placebo-controlled
Purpose
To evaluate oregano oil supplementation on gut symptoms and microbiome.
Dose
600 mg oregano oil daily (standardized to ≥70% carvacrol)
Participants
40 adults with functional GI symptoms
Duration
6 weeks
Results
Oregano oil significantly improved GI symptoms (bloating, pain) and reduced fecal calprotectin. Microbiome showed reduction in Enterobacteriaceae without major disruption of commensal bacteria.
How They Measured It
GI symptom diary, fecal microbiome (16S rRNA), calprotectin
To evaluate oregano oil as adjunct to H. pylori eradication therapy.
Study Type
Randomised controlled trial
Purpose
To evaluate oregano oil as adjunct to H. pylori eradication therapy.
Dose
200 mg oregano oil three times daily
Participants
56 H. pylori-positive patients
Duration
14 days
Results
Oregano oil adjunct showed higher eradication rate (82% vs 72% triple therapy alone, p=0.33). Significantly fewer GI side effects in oregano oil group.
How They Measured It
H. pylori eradication rate, therapy side effects
Antioxidant & Anti-inflammatory
To evaluate oregano oil supplementation on antioxidant status and inflammatory markers.
Study Type
Randomised, double-blind, placebo-controlled
Purpose
To evaluate oregano oil supplementation on antioxidant status and inflammatory markers.
Dose
600 mg oregano oil daily
Participants
48 hypercholesterolemic adults
Duration
3 months
Results
Oregano oil significantly reduced MDA and hs-CRP levels while increasing SOD and GPx activity, indicating improved antioxidant and anti-inflammatory status.
How They Measured It
Serum MDA, SOD, GPx, hs-CRP, IL-6
To evaluate anti-inflammatory mechanisms of carvacrol (oregano oil component) on intestinal epithelial cells.
Study Type
In vitro study
Purpose
To evaluate anti-inflammatory mechanisms of carvacrol (oregano oil component) on intestinal epithelial cells.
Dose
Various carvacrol concentrations
Participants
In vitro (Caco-2 intestinal cell line)
Duration
N/A
Results
Carvacrol dose-dependently inhibited NF-κB activation, reduced IL-8 secretion by 60%, and suppressed COX-2 expression in LPS-stimulated intestinal cells.
How They Measured It
NF-κB activation, IL-8 secretion, COX-2 expression in Caco-2 cells
Frequently Asked Questions
Common questions about Oregano Oil research
There are currently 7 peer-reviewed studies on Oregano Oil (Origanum vulgare (essential oil)), involving 264 total participants. Research covers Antimicrobial, Gut health, SIBO and 1 more areas. The overall evidence strength is rated as Strong.
The evidence is currently rated as "Strong Evidence". This rating is based on study design quality (randomisation, blinding, placebo controls), sample sizes, study types (5 human studies), and reported outcomes.
Oregano Oil has been researched for: Antimicrobial, Gut health, SIBO, Antioxidant. Each area has its own body of evidence which you can explore in the study breakdowns above.
Yes, 5 out of 7 studies are human trials. Human trials carry more weight in our evidence scoring system.
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