Herb & supplement monograph

Oregano Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS ·Updated July 2026

What is this page for?

First and foremost: how Oregano interacts with medications. The heart of this page is the interaction list — every drug Oregano is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Oregano is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Reviewed by licensed pharmacists Sourced from Natural Medicines

On this page

Interaction report

Drugs that interact with Oregano

208 medications have a known interaction with Oregano, graded by severity. Select any drug for the full evidence-based detail.

Don’t want to scroll the list? Just ask.

Tell us the medications you take and we’ll check each one against Oregano using our pharmacist-reviewed interaction data.

AI summaries are generated from our Oregano interaction data for education only — always confirm with your pharmacist. How we use AI

2,830 drugs

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
Probable. Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
Possible. Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
Each drug listed above links to the full report for that exact Oregano combination — clinical detail, likelihood, evidence level, and citations.
Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

The big picture

The kinds of drugs Oregano affects

Every type of medication (drug category) Oregano is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 2 drug categories Oregano interacts with

Anticoagulant/antiplatelet DrugsAntidiabetes Drugs

Anticoagulant/Antiplatelet Drugs

Theoretically, oregano might increase the risk of bleeding when taken with anticoagulant or antiplatelet drugs.
In vitro research shows that aristolochic acid isolated from oregano leaves has antithrombin activity. It has also been reported that oregano oil inhibits arachidonic acid-induced, and ADP-induced, platelet aggregation.

Likelihood Possible Evidence D

Antidiabetes Drugs

Theoretically, oregano might increase the risk for hypoglycemia when taken with antidiabetes drugs.
In vitro and animal research shows that oregano extracts might lower blood glucose levels.

Likelihood Possible Evidence D

Monograph

Oregano: Uses, Safety & Side Effects

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Reviewed July 2026 ·

The bottom line

Oregano is a common Mediterranean cooking herb that is also sold as a concentrated oil or supplement, often standardized for a compound called carvacrol. While lab studies suggest it may have antimicrobial and antioxidant properties, strong human evidence for treating any specific health condition is limited. Used as a food, oregano is very safe; concentrated oregano oil supplements should be used cautiously and discussed with your pharmacist or doctor.

Scientific name: Origanum vulgare
Family: Lamiaceae
Part used: Leaves and essential oil
Common forms: Culinary herb, tea, capsules, softgels, liquid oil (oil of oregano), tinctures

People commonly use it for

Digestive upset
Respiratory and cold symptoms
Antimicrobial support
Intestinal parasites
Skin and fungal concerns

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance

OverallUse caution

Safe as a food, but concentrated oregano oil supplements are stronger and less studied.

PregnancyPossibly Unsafe

When used orally in medicinal amounts. Oregano is thought to have abortifacient and emmenagogue effects.

Read the full pregnancy detail

BreastfeedingInsufficient reliable information

There is insufficient reliable information available about the safety of oregano when used in medicinal amounts; avoid amounts greater than those foun...

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

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Overview

Oregano is a fragrant perennial herb in the mint family (Lamiaceae) that is native to the Mediterranean region and now grows in many parts of the world. It has small leaves, a strong slightly bitter flavor, and tiny purple flowers. You probably know it best as a kitchen spice used in Italian, Greek, and Mexican cooking.

Beyond cooking, oregano is sold as a dietary supplement. The most common supplement form is oil of oregano (oregano oil), a concentrated extract often standardized to contain a set amount of carvacrol, one of its main active compounds. You can also find oregano as dried leaf, tea, capsules, and tinctures.

In traditional medicine, oregano has been used for digestive complaints, coughs and colds, and as a general antimicrobial. Modern interest focuses on its essential oil and the antioxidant compounds in the plant.

How it works

Oregano contains several plant compounds thought to be responsible for its proposed effects. The best known are carvacrol and thymol, which are part of the plant's essential oil. It also contains rosmarinic acid and various flavonoids that act as antioxidants.

In laboratory studies, carvacrol and thymol appear to damage the outer membranes of certain microbes, which may explain the herb's reputation as an antimicrobial. The antioxidant compounds may help neutralize unstable molecules called free radicals.

It is important to remember that these mechanisms come mostly from test tube and animal research. Showing an effect in a lab dish does not prove the same thing happens in the human body at the amounts people take.

Effectiveness

Does Oregano work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by Dr. Brian Staiger, PharmD.

Evidence overview · 26 uses evaluated

26 Insufficient evidence

How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.

2Likely EffectiveGood evidence, though not yet conclusive.

3Possibly EffectiveSome evidence suggests a benefit.

4Possibly IneffectiveSome evidence it may not help.

5Likely IneffectiveFairly strong evidence it doesn’t help.

6IneffectiveStrong evidence it doesn’t work.

7Insufficient Reliable Evidence to RateToo little research to say either way.

For Oregano, current evidence isn’t strong enough to rate any specific use. The conditions it has been studied for are listed below.

Also studied for 26 conditions — evidence insufficient to rate

Insufficient Reliable Evidence To Rate Acne