What is the side effect of cilantro? Understanding the Risks and Allergic Reactions

October 28, 2025 •

3 min read

While cilantro is generally safe in food amounts, some individuals experience adverse reactions ranging from mild digestive upset to severe allergic responses. Beyond the well-known genetic predisposition that makes the herb taste like soap, it's crucial to understand what is the side effect of cilantro, particularly for those with existing health conditions or sensitivities.

Quick Summary

This article explores the potential adverse effects associated with consuming cilantro, including allergic reactions, digestive disturbances, and its impact on certain medications. It also covers important food safety considerations and offers guidance on how to identify sensitivities.

Key Points

Allergic reactions: A cilantro allergy, though rare, can cause symptoms ranging from hives and swelling to severe, potentially fatal anaphylaxis.
Digestive distress: Consuming large, medicinal doses of cilantro can lead to gastrointestinal issues like bloating, gas, nausea, and diarrhea.
Drug interactions: Cilantro contains vitamin K, which can interfere with blood-thinning medications, and psoralen, which increases sensitivity to sunlight when combined with photosensitizing drugs.
Photosensitivity: The psoralen in cilantro can make some individuals' skin more sensitive to sunlight, increasing the risk of sunburn.
Food contamination: Improperly handled cilantro has been linked to outbreaks of parasitic infections like cyclosporiasis, causing severe intestinal illness.
Not a magical detox: The use of high-dose cilantro for heavy metal detox is not proven in clinical settings and can cause adverse side effects.
Genetic taste preference vs. allergy: A distaste for cilantro due to a genetic variant is not a side effect, and does not pose a physical health risk.

Allergic Reactions to Cilantro

Although rare, allergic reactions to cilantro are a documented possibility for some individuals. These reactions can manifest in various ways, from mild skin irritation to severe, life-threatening anaphylaxis. Psoralen, a compound found in cilantro, can also cause photosensitivity in some individuals, making their skin more susceptible to sunburn when exposed to ultraviolet light.

Symptoms of a cilantro allergy

Symptoms of a cilantro allergy can vary in severity and may include:

Hives and skin rashes.
Swelling of the lips, face, and throat.
Itching or tingling in the mouth.
Asthma-like symptoms, including coughing and wheezing.
Gastrointestinal distress, such as stomach pain, cramps, and diarrhea.

In severe cases, a cilantro allergy can lead to anaphylaxis, a medical emergency requiring immediate attention. Signs of anaphylaxis include difficulty breathing, dizziness, a weak pulse, and shock.

Digestive Issues and Excessive Intake

For most people, cilantro in typical culinary quantities poses no digestive threat. However, consuming it in large, medicinal amounts can lead to gastrointestinal distress. This can be particularly true for individuals with sensitive stomachs or pre-existing gastrointestinal conditions, like irritable bowel syndrome (IBS).

Potential digestive complaints

Bloating and gas: The high fiber content in large quantities of cilantro can cause digestive discomfort for some.
Nausea and diarrhea: Overconsumption can lead to nausea and, in some cases, diarrhea.
Stomach cramps: Painful abdominal cramping can occur, particularly when large amounts of cilantro extract are consumed.

Drug Interactions and Other Health Risks

Cilantro contains vitamin K, a nutrient that plays a crucial role in blood clotting. While the amount in standard culinary use is small, consuming large quantities can affect individuals on certain medications or with specific health conditions.

Important interactions to consider

Blood-thinning medications: The vitamin K in cilantro can counteract the effects of anticoagulant medications like warfarin (Coumadin), potentially increasing the risk of blood clots. Individuals on these drugs should maintain a consistent intake of vitamin K and consult their doctor before altering their diet significantly.
Photosensitizing drugs: For individuals taking medications that increase sensitivity to sunlight, such as certain antibiotics (e.g., Cipro) and antidepressants (e.g., Elavil), the psoralen in cilantro can amplify this effect, increasing the risk of sunburn.
Medications for blood pressure and diabetes: There is preliminary evidence suggesting cilantro may affect blood sugar and blood pressure levels. Those on medication for these conditions should exercise caution when consuming large, medicinal amounts.

Food Safety Concerns

Contamination is another potential risk associated with cilantro, though this is not an intrinsic side effect of the herb itself. Outbreaks of illnesses, such as cyclosporiasis caused by the parasite Cyclospora cayetanensis, have been linked to contaminated cilantro. Proper washing and food handling practices are critical to mitigate this risk.

Cilantro vs. Cilantro Sensitivity: Clarifying the Difference


Feature	Allergic Reaction	Genetic Sensitivity (Soap Taste)
Mechanism	An immune system response to specific proteins in cilantro.	Genetic variation in the olfactory receptor gene OR6A2.
Symptoms	Hives, swelling, digestive issues, breathing problems, anaphylaxis.	A perception of a soapy or metallic taste, with no physical harm.
Health Risk	Can be life-threatening and requires medical attention.	Poses no physical health risk; is simply a matter of taste perception.
Management	Strict avoidance of cilantro and seeking medical care.	Personal preference; can avoid or use alternative herbs.

The Detoxification Myth and Side Effects

Some popular health claims suggest cilantro is a powerful detoxifier for heavy metals. While cilantro has chelating properties in laboratory settings, using it for this purpose in high doses without medical supervision is not well-supported by robust clinical evidence and can cause side effects. Symptoms like gastrointestinal issues, allergic reactions, and interactions with other medications can occur, highlighting the need for caution.

Conclusion

While a common and nutritious herb, understanding what is the side effect of cilantro is important for maintaining health, especially for those with specific sensitivities or medical conditions. For most, consuming cilantro in typical food amounts is safe and beneficial. However, those with a known allergy, individuals on blood-thinning or photosensitizing medications, and anyone consuming large, medicinal quantities should be aware of the potential risks. Practicing proper food safety and consulting a healthcare provider if concerns arise are the most effective strategies for enjoying the herb safely. For more general information on nutrition and food safety, the U.S. Food and Drug Administration (FDA) website is an authoritative source. https://www.fda.gov/

Frequently Asked Questions

Yes, while cilantro is generally known for aiding digestion in small amounts, consuming it in large, medicinal quantities can cause digestive issues such as bloating, gas, nausea, and diarrhea, especially in sensitive individuals.

No, a cilantro allergy is considered rare. However, it can occur and may cause reactions ranging from mild skin irritation and mouth swelling to severe, life-threatening anaphylaxis.

Cilantro contains vitamin K, a nutrient that helps blood clot. In very large amounts, this can counteract the effects of anticoagulant medications like warfarin, potentially increasing the risk of blood clots.

Yes, some individuals may experience photosensitivity due to compounds called psoralens in cilantro. This can make their skin more vulnerable to sunburn and rashes when exposed to sunlight.

A cilantro allergy is an immune system response with physical symptoms like hives, swelling, or digestive distress. Disliking the taste is a harmless genetic trait, often described as tasting like soap, and does not involve a physical reaction.

While cilantro has shown some chelating properties in lab studies, there is insufficient evidence to support using it for heavy metal detoxification in high doses in humans. Unsupervised use can lead to side effects and drug interactions.

If you experience a mild reaction, stop consuming cilantro. If you show signs of a severe reaction like difficulty breathing, call emergency services immediately, as this could be anaphylaxis.