Oregano oil may interfere with your meds, new study warns
NCT ID NCT06693960
First seen Jun 27, 2026 · Last updated Jun 27, 2026
Summary
This early-phase trial at Washington State University is testing whether oregano supplements affect how the body breaks down common drugs. Sixteen healthy adults will take oregano oil alongside a cocktail of five drugs (caffeine, dextromethorphan, losartan, midazolam, and omeprazole). Researchers will measure drug levels in the blood to see if oregano changes their metabolism. The goal is to understand potential herb-drug interactions, not to treat any disease.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- Active substance
- oregano oil (dietary supplement)
- What this could lead to
- If it works, this could help people know whether taking oregano supplements changes how their medications work.
- What could go wrong
- This is a very small, early-phase study in healthy people, not patients. Results may not apply to everyone, and oregano might not affect drug metabolism at all.
This is an AI summary of the original study and may miss details. Read our disclaimer.
Study facts
What this study's own registry entry says, in plain language.
- Phase
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Early phase 1
The earliest testing in people: a first look at safety, in a very small group.
- Participants
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About 16 people
The number the study aims to enrol. It can still change while the study runs.
- Started
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Sep 2024
- Expected to finish
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Jan 2027
An estimate. End dates often move.
- Lead sponsor
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Other sponsor
The registry's catch-all category, for sponsors it does not file as a company, a government agency, or a research network.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
- Ages
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18 to 64 years
- Sex
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Anyone
- Healthy volunteers
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Accepted
You do not need to have the condition being studied to take part.
Show the full entry requirements Hide the full entry requirements
Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
Inclusion Criteria: * Between 18-64 years old and healthy * Not taking any medications (prescription and non-prescription) or dietary/herbal supplements that can interfere with study drug pharmacokinetics * Willing to abstain from consuming dietary/herbal supplements and citrus juices for several weeks * Willing to abstain from cannabis/marijuana, hemp, and THC- and CBD-containing products for several weeks * Willing to abstain from consuming caffeinated beverages or other caffeine-containing products the evening before and the morning of the first day of each study arm * Willing to abstain from consuming any alcoholic beverages for at least 1 day prior to any study day and during the study day * Willing to use a secondary method of birth control that does not include the introduction or discontinuance of hormonal-based birth control (such as abstinence, copper IUD, or condoms). Specifically, regardless of the use hormonal-based birth control, a non-hormonal method should be used for the duration of the study and for three weeks following cessation of participation. * Willing to abstain from consuming oregano (as a food additive or otherwise) for the duration of the study * Geographically located within a 40-mile radius of Spokane and have the time to participate Exclusion Criteria: * Under 18 or over 64 years old * Taking medications or dietary/herbal supplements that can interfere with study drug pharmacokinetics * Have a major illness * Taking medication/supplements for a mineral deficiency * History of intolerance or allergy to oregano or any of the cocktail drugs (caffeine, dextromethorphan, losartan, midazolam, and omeprazole) * Use of cannabis/marijuana, hemp, and CBD- and/or THC-containing products within the last month * Currently using drugs or illicit substances for recreational purposes * Pregnant or nursing * Geographically located outside the 40-mile radius of Spokane and do not have the time to participate * Cannot read and speak English
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As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
How to take part
Only the study team decides who joins. These are the ways to reach them.
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The places running it
1 site. The list below names each one and where it is.
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The official record
ClinicalTrials.gov lists the study team's own contact details, including names and phone numbers. We don't republish those.
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A doctor treating you
A doctor who knows your case can contact a study site on your behalf, and can tell you whether this study is worth pursuing at all.
Contacts and locations
Locations
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Washington State University College of Pharmacy and Pharmaceutical Sciences
RECRUITINGSpokane, Washington, 99202, United States
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