What is cilantro and how does it affect the body?
Cilantro, also known as coriander leaves, is a popular culinary herb with a wide range of potential health benefits attributed to its high content of antioxidants, vitamins, and other bioactive compounds. Beyond its flavor, traditional medicine and modern studies suggest it has anti-inflammatory, antimicrobial, and anxiolytic (anxiety-reducing) properties. Some of the mechanisms identified in research include stimulating enzymes that remove sugar from the blood, affecting potassium channels that regulate cellular excitability, and containing high levels of vitamin K. However, these same powerful properties are what necessitate caution when consuming cilantro alongside certain medications.
Cilantro and blood-thinning medications
One of the most significant and well-documented interactions involves blood-thinning medications, specifically warfarin (Coumadin). The core issue is cilantro's high vitamin K content, a vitamin essential for blood clotting. Warfarin works by interfering with the function of vitamin K to prevent blood clots. A sudden increase in vitamin K intake, such as from large amounts of cilantro or supplements, can counteract warfarin's effects and decrease its blood-thinning potency. This can lead to an increased risk of dangerous blood clots, heart attacks, or strokes. Patients on warfarin should maintain a consistent intake of vitamin K, meaning large fluctuations in cilantro consumption should be avoided. Any significant change in diet should be discussed with a healthcare provider to ensure proper dosage adjustment.
Cilantro and diabetes medications
For those managing diabetes, cilantro poses a different but equally important risk. Studies, primarily in animals, have shown that cilantro can lower blood sugar levels. It is believed to stimulate enzymes that help remove sugar from the blood. When a person taking diabetes medication, such as glibenclamide, also consumes significant amounts of cilantro, their blood sugar could drop too low, leading to hypoglycemia. This can be a serious medical concern. Patients with diabetes or those with low blood sugar should monitor their glucose levels carefully, especially if they are adding cilantro supplements or large amounts of the herb to their diet.
Other potential medication interactions
- Blood Pressure Medications: Research suggests cilantro may have a blood pressure-lowering effect due to its antioxidant and potassium content. Combining large quantities of cilantro or supplements with antihypertensive drugs could cause blood pressure to drop too low, a condition known as hypotension.
- Sedatives: Animal studies have indicated that high doses of cilantro extract produce anti-anxiety and sedative effects, similar to the prescription drug Valium. This is linked to a compound called dodecenal activating potassium channels in the brain. Taking cilantro with other sedatives might lead to excessive sleepiness or breathing problems.
- Photosensitizing Drugs: Cilantro might increase sensitivity to sunlight. Patients taking medications that also increase photosensitivity, such as certain antibiotics (e.g., ciprofloxacin) or antidepressants (e.g., amitriptyline), could face an increased risk of sunburn, rashes, or blistering when exposed to the sun.
Culinary vs. supplemental cilantro
The risk of interaction is highly dependent on the amount consumed. Most studies pointing to significant pharmacological effects use concentrated extracts of cilantro leaves or coriander seeds, often in doses far higher than a person would consume in their daily diet.
Culinary amounts: The small quantities of cilantro used for seasoning and garnishing are generally considered safe for most people, though consistency is key for those on warfarin. The effects of these small amounts are typically not potent enough to cause major drug interactions.
Supplemental amounts: Cilantro supplements, sold as capsules or extracts, contain a highly concentrated dose of the herb's active compounds. This dramatically increases the risk of drug interaction and side effects. Supplement users are the most vulnerable to experiencing the pharmacological effects that interfere with medications.
Who should be cautious with cilantro?
- Individuals on blood-thinning medications, especially warfarin.
- People with diabetes or hypoglycemia.
- Patients taking medication for high blood pressure.
- Those on sedatives or anti-anxiety medications.
- Individuals taking photosensitizing drugs.
- People with bleeding disorders.
- Those with known allergies to similar plants like fennel, dill, or anise.
Key differences: Cilantro (culinary) vs. Concentrated Supplements
| Feature | Culinary Cilantro (fresh leaves) | Cilantro Supplements (concentrated extract) |
|---|---|---|
| Potency | Low. Used for flavoring, not medicinal effect. | High. Concentrated for a stronger pharmacological effect. |
| Quantity | Small, inconsistent amounts in meals. | Large, consistent, and standardized doses. |
| Risk of Interaction | Low, except for those needing strict vitamin K control (e.g., warfarin patients) where fluctuations in diet matter. | Significantly higher, especially with blood thinners, diabetes drugs, and sedatives. |
| Medical Oversight | Generally not required for minor culinary changes, but consistency is vital for warfarin patients. | Strongly recommended to consult a doctor, as supplement effects can be potent. |
Conclusion
While cilantro is a common and usually harmless herb, its potential for interacting with certain medications cannot be ignored, particularly when consumed in concentrated forms like supplements. The key takeaway is moderation and consistency. For individuals taking medications for blood clotting, diabetes, or blood pressure, large fluctuations in cilantro intake should be avoided. Always remember that even natural compounds can have powerful effects on the body. Before starting any new herb or supplement regimen, it is best to speak with a healthcare professional to ensure it is safe and won't interfere with your current medications or health conditions. For further guidance on herb-drug interactions, a reliable resource is the National Center for Complementary and Integrative Health (NCCIH).
