Oregano Oil

Origanum vulgare · Oil of oregano · Carvacrol

Snapshot

Indications	Contraindications
Asthma symptoms¹ Sulfur mustard lung injury^{2, 3} Periodontitis adjunct⁴ Small intestinal bacterial overgrowth⁵ Minor bacterial infection⁶ Inflammatory markers⁷	Pregnancy⁸ Breastfeeding⁸

Oregano oil is the volatile oil of Origanum vulgare, about four-fifths carvacrol in one analyzed sample, a phenolic monoterpene that acts largely through antimicrobial and anti-inflammatory activity. Supplementation is used for its antibacterial effect, including intestinal bacterial overgrowth, for respiratory inflammation, and for oral and periodontal care. Typical users are adults seeking a botanical alternative for gut, airway, or gum complaints.

Human research is limited to about five small trials, mostly of carvacrol in asthma and sulfur mustard lung injury. Randomized trials of carvacrol found improved respiratory symptoms and lung function in these groups, and a phase I study in healthy adults found it clinically tolerable. In 2025, a 30-adult observational study of an Origanum vulgare gel in periodontitis found reduced periodontal bacteria and improved probing measures, with no controlled trial yet⁴. Products are mostly oregano oil softgels and capsules; see Form comparison.

Last updated October 16, 2026. Read how we make monographs.

In the full monograph

60 sources, 44 studies

When to useThe situations practitioners use it for, each with the reason and the study behind it.
SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
InteractionsThe medicines and supplements it interacts with, the effect of each, and what labeling says to watch.
Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
How it worksWhat it is and how it works in the body, in plain terms.
Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.

Snapshot

In the full monograph

Sources