Oil of oregano, a concentrated extract from the oregano plant, is well-known for its active compounds, primarily the phenols carvacrol and thymol [1.8.5]. These compounds are responsible for its antioxidant and antimicrobial properties, but they are also the source of potential interactions with various medications and supplements [1.8.5, 1.9.4]. Understanding these reactions is essential for using it safely.
The Pharmacology Behind the Interactions
The primary active components in oil of oregano, carvacrol and thymol, can influence the body in several ways that affect how other substances are processed [1.8.5]. One significant mechanism is the potential inhibition of Cytochrome P450 enzymes in the liver [1.5.3, 1.2.6]. These enzymes are crucial for metabolizing a vast number of common medications. By slowing down this process, oil of oregano can cause some drugs to accumulate in the body, increasing their effects and the risk of toxicity [1.2.6]. Furthermore, the oil itself has physiological effects, such as lowering blood sugar and slowing blood clotting, which can lead to additive effects when combined with drugs designed for the same purpose [1.2.2].
Key Drug Interactions to Be Aware Of
Caution is advised when considering oil of oregano alongside prescription medications. The most well-documented interactions involve drugs that affect blood clotting and blood sugar levels.
Anticoagulant and Antiplatelet Drugs
Oil of oregano has properties that can slow blood clotting [1.2.2]. When taken with anticoagulant (blood thinner) medications like warfarin (Coumadin), heparin, or direct oral anticoagulants like apixaban (Eliquis) and rivaroxaban (Xarelto), it may increase the risk of bleeding and bruising [1.2.1, 1.3.1]. This also applies to antiplatelet drugs such as aspirin and clopidogrel (Plavix) [1.2.1]. The concern is that the supplement's natural blood-thinning effect can compound the medication's action, leading to an excessive anticoagulant response [1.3.2].
Diabetes Medications
Oregano might lower blood sugar levels [1.4.1]. For individuals managing diabetes with medications such as metformin, insulin, glimepiride, or glyburide, adding oil of oregano could cause blood sugar to drop too low, a condition known as hypoglycemia [1.4.2, 1.4.4]. Close monitoring of blood sugar is essential for anyone with diabetes who chooses to use this supplement [1.4.1].
Lithium and Diuretics
There is evidence to suggest that oil of oregano may have diuretic properties, meaning it can increase urine flow [1.5.2, 1.4.5]. This could potentially affect the body's ability to clear lithium, a medication used for bipolar disorder, possibly leading to dangerously high levels [1.5.4, 1.4.6]. The additive effect with other diuretic medications could also lead to dehydration or electrolyte imbalances [1.4.5].
Interactions with Other Supplements
The potential for interaction is not limited to prescription drugs. Care should be taken when combining oil of oregano with other natural health products.
- Herbs that Affect Blood Clotting: Supplements like garlic, ginkgo, ginger, and some types of ginseng also have blood-thinning properties. Combining them with oil of oregano can further increase the risk of bleeding [1.7.1, 1.7.2].
- Herbs that Lower Blood Sugar: Herbs such as bitter melon, chromium, and aloe can also reduce blood sugar levels. Taking them alongside oil of oregano can heighten the risk of hypoglycemia [1.7.2].
- Mineral Absorption: Some sources indicate that oregano may decrease the body's absorption of iron, copper, and zinc. It is often recommended to take oregano supplements at least two hours before or after these mineral supplements [1.2.3, 1.5.1].
Comparison of Effects: Oil of Oregano vs. Medications
| Substance/Drug | Primary Pharmacological Action | Potential Interaction with Oil of Oregano |
|---|---|---|
| Oil of Oregano | Might slow blood clotting, may lower blood sugar [1.2.2] | Baseline effect that can be amplified by other agents. |
| Warfarin (Coumadin) | Anticoagulant; inhibits vitamin K-dependent clotting factors. | Additive effect; increases the risk of bleeding and bruising [1.2.1]. |
| Aspirin | Antiplatelet; irreversibly inhibits COX-1 and COX-2 enzymes. | Additive effect; increases the risk of bleeding [1.2.1]. |
| Metformin (Glucophage) | Antidiabetic; decreases hepatic glucose production. | Additive effect; increases the risk of hypoglycemia (low blood sugar) [1.4.4]. |
| Garlic/Ginkgo | Herbal supplements that may slow blood clotting [1.7.2]. | Additive effect; compound increase in bleeding risk [1.7.1]. |
Who Should Avoid Oil of Oregano?
Certain populations should exercise particular caution or avoid the supplement altogether:
- Pregnant and Breastfeeding Women: Due to its potential to stimulate uterine blood flow and a lack of safety data, it is not recommended during pregnancy or while breastfeeding [1.5.3, 1.8.2].
- Individuals with Bleeding Disorders: Those with conditions like hemophilia should avoid oregano as it might increase bleeding risk [1.4.4].
- Individuals Scheduled for Surgery: It is recommended to stop taking oil of oregano at least two weeks before any surgical procedure to prevent excessive bleeding [1.2.1, 1.5.2].
- People with Allergies: Individuals allergic to plants in the Lamiaceae family (basil, lavender, mint, sage) may also be allergic to oregano [1.5.1].
- Infants and Children: Use in children is not recommended without guidance from a healthcare professional [1.8.5].
Conclusion
While oil of oregano offers potential health benefits stemming from its potent compounds, it also presents a real risk of interactions. Its ability to influence blood clotting, lower blood sugar, and potentially alter drug metabolism means it should not be taken lightly. Before adding oil of oregano to a health regimen, especially if you take any prescription medications or have an existing health condition, consulting with a physician or pharmacist is a critical step to ensure safety.
