What are the side effects of cloves?

September 22, 2025 •

4 min read

While lauded for their antioxidant properties, the compound eugenol, especially concentrated in clove oil, can pose serious health risks in high doses. This article explores what are the side effects of cloves to ensure safe consumption and use.

Quick Summary

Cloves can cause side effects ranging from allergic reactions and skin irritation to potential blood thinning and dangerously low blood sugar levels, particularly when consumed in high doses or as concentrated oil. Extreme caution is needed with clove oil, which can be toxic if ingested, especially by children.

Key Points

Clove Oil Toxicity: Ingesting concentrated clove oil is highly dangerous and can lead to severe liver damage, seizures, and coma, especially in children.
Blood-Thinning Properties: The eugenol in cloves can slow blood clotting, posing a risk for individuals with bleeding disorders or those on anticoagulant medications like warfarin.
Hypoglycemia Risk: High doses of cloves can lower blood sugar levels, which is particularly dangerous for people with diabetes taking blood-sugar-lowering medication.
Skin Irritation: Applying undiluted clove essential oil topically can cause painful burning, irritation, and allergic contact dermatitis.
Precaution for Vulnerable Groups: Pregnant women, breastfeeding mothers, children, and individuals with liver disease or bleeding disorders should avoid high doses and supplements.
Culinary vs. Medicinal Use: While culinary amounts are generally safe, using cloves for medicinal purposes or in concentrated forms like essential oil carries much higher risks and should be done with professional medical advice.

Understanding the Risks: Clove Oil vs. Whole Cloves

When discussing the side effects of cloves, it is crucial to differentiate between consuming the spice in culinary amounts and using highly concentrated clove oil. While adding cloves to food is generally safe for most people, the essential oil contains a potent concentration of the active compound, eugenol, which poses significant risks when misused.

The Dangers of Clove Oil

Clove essential oil is not intended for ingestion and can be highly toxic. Medical literature documents severe cases of overdose, most notably in young children who accidentally consumed even small quantities. These incidents underscore the oil's dangerous potential.

Liver Damage and Seizures: Ingesting concentrated clove oil can lead to serious health complications, including liver failure, seizures, and coma. The eugenol acts as a direct cytotoxin, causing acute hepatic necrosis in large doses.
Kidney Injury: High doses of eugenol can also damage the kidneys, leading to renal dysfunction.
Respiratory Problems: Inhaling clove oil, particularly from clove cigarettes (kreteks), has been linked to severe lung injury, including pneumonia and pulmonary edema.
Skin and Mucous Membrane Irritation: Applying undiluted clove oil topically, especially to sensitive areas like gums, can cause severe burning, pain, redness, and irritation. Dentists have used eugenol in past applications, but its use can lead to local irritation and hypersensitivity.

Side Effects from Excessive Clove Consumption

While the risk is far lower with culinary use, consuming cloves in high, non-food-related amounts can still cause adverse effects due to their eugenol content.

Hypoglycemia: Cloves can have a blood-sugar-lowering effect. For individuals with diabetes, especially those on insulin, consuming high doses could cause blood sugar levels to drop too low, resulting in a dangerous condition called hypoglycemia.
Blood-Thinning Effects: Eugenol seems to slow blood clotting. This poses a significant risk for individuals with bleeding disorders or those taking anticoagulant medications like warfarin, as it can increase the risk of bleeding and bruising.
Digestive Upset: Excessive intake can irritate the stomach lining, leading to symptoms like nausea, heartburn, and diarrhea.
Allergic Reactions: Though less common, allergic reactions can occur from either consumption or topical exposure. Symptoms may include hives, itching, swelling, or, in severe cases, anaphylaxis.

Who Should Be Cautious with Cloves?

Not everyone can enjoy cloves without concern. Certain populations and individuals with pre-existing conditions should exercise extreme caution or avoid them altogether. The following table provides a clear overview.


Group	Culinary Spice (Low Risk)	Clove Oil / High Doses (High Risk)
Children	Minimal amounts are likely safe	Avoid completely; ingestion can cause liver failure and seizures.
Pregnant/Breastfeeding Women	Generally safe in food amounts	Not enough safety data exists; avoid supplements and oil.
Diabetic Patients	Monitor blood sugar closely	Avoid high doses and supplements, which can cause hypoglycemia.
Bleeding Disorders/Anticoagulant Users	Minimal amounts generally safe, but consult doctor	Avoid entirely due to potential blood-thinning effects.
Before Surgery	Avoid for at least two weeks	Avoid entirely due to effects on blood sugar and clotting.
Individuals with Liver Disease	Consult with a healthcare provider	Avoid due to the risk of exacerbating liver problems.

Safe Usage and Practical Advice

Moderation is key when it comes to cloves. The safest way to enjoy them is as a culinary spice in meals or baked goods. Here are some practical tips for safe usage:

Use whole or ground spice sparingly: Add a few cloves to mulled drinks, stews, or baked items. The low concentration of eugenol is unlikely to cause issues in most adults.
Avoid homemade clove water: Steeping cloves in water to make a tea can release higher concentrations of eugenol, making the dosage unpredictable and potentially unsafe.
Exercise extreme caution with essential oils: Never ingest clove essential oil. When using it topically, it is best to dilute it significantly with a carrier oil like jojoba or coconut oil and perform a patch test to check for skin sensitivity.
Know your limits: If you experience any burning, redness, or allergic reaction after exposure, stop using the product immediately.
Consult a professional: Before using any clove supplements, extract, or oil for medicinal purposes, speak with a healthcare provider to ensure it is safe for your health status and will not interfere with other medications.

Conclusion: A Spice, Not a Supplement for Everyone

While cloves can be a wonderful and flavorful addition to cooking, their potent compounds, especially in concentrated forms, carry significant health risks. The potential side effects of cloves range from mild irritation to severe, life-threatening organ damage, particularly with essential oil ingestion. Understanding the difference between the low risk of culinary use and the high risk of concentrated applications is essential. Always consult a healthcare provider before using cloves medicinally, and prioritize safety, especially for children and those with pre-existing health conditions.

For more detailed information on the potential hepatotoxicity of eugenol and clove oil, consult authoritative medical resources like the NIH LiverTox page on Eugenol.

Frequently Asked Questions

Chewing on a single whole clove is unlikely to cause harm. However, chewing multiple cloves regularly or in high quantities can lead to digestive upset, mouth irritation, and other issues due to a higher concentration of eugenol than typically consumed in food.

Yes, cloves can interfere with certain medications. The eugenol they contain can slow blood clotting, which can be dangerous for people taking blood thinners like warfarin. Cloves can also lower blood sugar, potentially interacting with diabetes medications.

While historically used, applying undiluted clove oil directly to the gums can cause severe irritation, burning, and even permanent tissue damage. It is best to consult a dentist for safe and proven options for toothache relief.

A clove allergy can manifest as oral reactions, such as itching or swelling in the mouth, as well as skin irritation, hives, or a rash from topical exposure. In rare, severe cases, anaphylaxis may occur. Seek emergency medical help for serious symptoms.

Drinking clove tea or water is generally not recommended. There is no way to accurately measure the concentration of eugenol, and higher doses can lead to adverse effects. It is safer to consume cloves in culinary amounts within a recipe.

Clove oil should be avoided by pregnant or breastfeeding women, children, and individuals with bleeding disorders, diabetes, or liver disease. Ingesting clove oil is particularly dangerous for children.

In high doses, cloves can irritate the stomach lining. Some people may experience symptoms such as nausea, heartburn, or diarrhea, especially if they have a sensitive stomach.