As a popular herb in Mediterranean cuisine, rosemary is generally considered safe when used in typical food amounts. However, taking rosemary in medicinal quantities, such as in supplements, teas, or concentrated extracts, can lead to clinically significant interactions with several classes of medications. These interactions are due to the active compounds in rosemary, such as rosmarinic acid and other phytochemicals, which can influence various physiological processes in the body.
Rosemary and Anticoagulants (Blood Thinners)
One of the most significant interactions involves anticoagulants and antiplatelet drugs. Rosemary contains compounds that can inhibit platelet aggregation and thin the blood, similar to aspirin. When taken alongside prescription blood thinners, this effect is amplified, raising the risk of excessive bleeding and bruising. The interaction can be particularly dangerous during surgery or if an individual has a pre-existing bleeding disorder.
Common medications in this category that may interact include:
- Warfarin (Coumadin)
- Clopidogrel (Plavix)
- Aspirin
- Dalteparin (Fragmin)
- Enoxaparin (Lovenox)
- Heparin
Blood Pressure Medications and Rosemary
Rosemary can also interfere with medications used to treat high blood pressure, particularly ACE inhibitors. Research has found that certain substances in rosemary can bind to the same molecules as these medications. This can alter blood pressure levels and potentially interfere with the drug's effectiveness.
Interacting ACE inhibitors include:
- Captopril (Capoten)
- Enalapril (Vasotec)
- Lisinopril (Zestril)
The Effect on Diuretics and Lithium
Rosemary possesses natural diuretic properties, which means it promotes urination and helps the body shed excess fluid. This effect can be particularly dangerous when combined with prescription diuretics, or 'water pills', as it could increase the risk of dehydration.
For individuals taking lithium, the diuretic effect is of even greater concern. By causing the body to lose too much water, rosemary can lead to a toxic buildup of lithium in the bloodstream. Lithium levels must be carefully monitored, and any substance that alters fluid balance could have severe consequences.
Rosemary and Diabetes Medications
Some research suggests that rosemary can lower blood sugar levels. For individuals with diabetes, this effect, when combined with antidiabetes drugs, can lead to hypoglycemia (dangerously low blood sugar). Close monitoring of blood sugar is essential for anyone using rosemary in medicinal amounts while on diabetes medication.
Additional Considerations and Precautions
Beyond these major interactions, rosemary can also affect other medications and conditions. The herb contains salicylates, chemicals similar to aspirin, which means it should be used cautiously by those with an aspirin allergy. For individuals with seizure disorders, high doses of rosemary might worsen their condition. Additionally, rosemary can influence liver enzymes (specifically Cytochrome P450 1A1 and 1A2) that metabolize certain medications, potentially altering the drug's effects.
Comparison of Rosemary's Drug Interactions
| Drug Class | Rosemary's Effect | Interaction Risk | Precautionary Action |
|---|---|---|---|
| Anticoagulants | May slow blood clotting. | Increased risk of bleeding or bruising. | Avoid medicinal use; consult doctor before taking supplements. |
| ACE Inhibitors | May interfere with mechanism. | Reduced effectiveness of blood pressure control. | Consult doctor before use, especially in high doses. |
| Diuretics | Natural diuretic effect. | Increased risk of dehydration and electrolyte imbalance. | Monitor fluid balance closely; consult doctor. |
| Lithium | Natural diuretic effect. | Risk of lithium toxicity due to fluid loss. | Absolute contraindication for medicinal use; very dangerous. |
| Diabetes Drugs | May lower blood sugar levels. | Increased risk of hypoglycemia (low blood sugar). | Monitor blood sugar closely and adjust medication if necessary. |
| Salicylates | Contains salicylate-like compounds. | Potentiated effects and side effects of other salicylates. | Use with caution, especially if allergic to aspirin. |
Conclusion
While a delicious and aromatic culinary herb, concentrated rosemary in supplement or tea form can significantly interact with several important medications. The potential for dangerous side effects, such as increased bleeding risk with anticoagulants or lithium toxicity from diuretic effects, means that medicinal use of rosemary should always be discussed with a healthcare provider. Individuals with specific health conditions, including diabetes, high blood pressure, bleeding disorders, or seizure disorders, should be particularly cautious. Always prioritize professional medical advice before adding any new supplement or high-dose herbal remedy to your routine, even those from a common pantry herb. For authoritative drug information, consult sources like the U.S. National Library of Medicine.
