What Are the Side Effects of Cloves in the Body?

January 7, 2026 •

3 min read

While cloves have been a prized spice and traditional remedy for centuries, high concentrations, particularly from clove oil, can cause serious side effects. It is important to understand the potential risks associated with excessive or inappropriate use, especially for vulnerable groups.

Quick Summary

Excessive intake of cloves or concentrated clove oil can lead to liver toxicity, dangerously low blood sugar, increased bleeding risk, and severe allergic reactions. Topical use can cause oral and skin irritation, and specific populations should exercise caution.

Key Points

High-Dose Toxicity: Ingesting concentrated clove oil can cause severe side effects, including liver damage, seizures, and fluid imbalances, and is especially dangerous for children.
Blood-Thinning Properties: The eugenol in cloves can slow blood clotting, posing a risk of increased bleeding for those on anticoagulant medications or before surgery.
Hypoglycemia Risk: Cloves can lower blood sugar, which is a concern for people with diabetes taking medication, as it may cause dangerous drops in blood glucose.
Topical Irritation: Undiluted clove oil is a potent irritant that can cause a burning sensation and tissue damage when applied to the skin or sensitive oral mucous membranes.
Drug Interactions: Eugenol can interact with several medications, including blood thinners and diabetes drugs, altering their effectiveness or increasing side effects.
Allergic Reactions: Though uncommon, allergic reactions to cloves or eugenol can occur, manifesting as skin rashes, itching, or, in rare severe cases, anaphylaxis.

The Chemical Culprit: Eugenol

At the heart of both the benefits and risks of cloves is eugenol, a potent aromatic compound that constitutes 70% to 90% of clove oil. While eugenol offers therapeutic properties, it is also a powerful substance that, in high doses, can become toxic to human cells. The concentration of eugenol is key to understanding the difference between safely enjoying cloves in your cooking versus the dangers of ingesting or improperly applying the highly concentrated essential oil.

Ingestion of Clove Oil and Toxicity

Ingesting even small amounts of pure clove oil can be highly toxic and has been linked to severe health emergencies, particularly in children. Overdose symptoms can manifest rapidly and may include:

Central Nervous System Depression: Leading to symptoms like drowsiness, decreased alertness, and in severe cases, coma.
Fluid and Electrolyte Imbalances: Can become life-threatening if left untreated.
Seizures: Especially concerning in infants and young children, whose delicate metabolisms are more susceptible to eugenol toxicity.

Significant Health Complications of High Clove Intake

Excessive intake, especially via clove oil or supplements, can directly harm several organ systems.

Liver and Kidney Damage

Eugenol is metabolized by the liver, and high doses can overwhelm its capacity, leading to direct cytotoxic effects on liver cells. Documented cases of acute liver injury from ingesting concentrated clove oil show symptoms like jaundice, elevated liver enzymes, and sometimes hepatic necrosis. This places individuals with pre-existing liver conditions at a significantly higher risk. In overdose cases, kidney damage can also occur.

Blood-Thinning Effects

Eugenol possesses blood-thinning properties by slowing blood clotting. For individuals on anticoagulant or antiplatelet medications, such as warfarin or aspirin, consuming cloves in medicinal amounts can amplify the risk of bruising and bleeding. Medical guidelines suggest stopping clove supplements at least two weeks before any scheduled surgery to prevent excessive bleeding during and after the procedure.

Hypoglycemia

Studies suggest that compounds in cloves can help regulate blood sugar, which can be beneficial for some. However, this poses a serious risk for diabetic individuals, particularly those on insulin or other glucose-lowering drugs. Combining high-dose clove supplements with diabetes medication can cause blood sugar levels to drop dangerously low, leading to a condition known as hypoglycemia. Symptoms may include dizziness, fatigue, and confusion.

Localized and Allergic Reactions

Concentrated clove preparations can cause adverse effects on the skin and mouth.

Oral and Skin Irritation

Applying undiluted clove oil directly to sensitive areas, like the gums or skin, can cause irritation, burning sensations, and even tissue damage. Repeated or frequent use can lead to gum damage and inflammation of the mucous membranes in the mouth. A patch test is recommended before topical application to check for sensitivity.

Allergic Reactions

Although rare, some individuals may experience allergic reactions to cloves or eugenol. Symptoms of a reaction can include contact dermatitis, rashes, itching, and swelling. In severe cases, a systemic allergic response, known as anaphylaxis, can occur, causing breathing difficulties and swelling of the throat, which requires immediate medical attention.

Comparison: Culinary vs. Concentrated Cloves

To illustrate the difference in risk, the following table compares common culinary use with concentrated forms like essential oil.


Feature	Culinary Cloves (as a spice)	Concentrated Clove Oil/Extract
Eugenol Content	Low concentration	Very high concentration (70-90%)
Safety	Generally recognized as safe (GRAS) by the FDA for food use.	Unsafe for internal use due to toxicity, especially for children.
Digestive Effects	Can aid digestion in small amounts.	High doses can cause stomach irritation, nausea, and vomiting.
Effect on Blood	Minimal effect on blood clotting at culinary levels.	Significant blood-thinning effect; interacts with anticoagulant medication.
Liver Risk	Negligible risk in food amounts.	Potential for severe liver damage and acute injury, especially in overdoses.
Topical Risk	Not typically used topically.	Can cause severe skin and mucosal irritation; requires dilution.

Conclusion: Responsible Use is Paramount

Cloves are a valuable spice with potential health benefits when used appropriately. However, the side effects of cloves, particularly in concentrated forms, can be significant and dangerous. The key to safety lies in moderation and understanding the critical difference between culinary use and medicinal applications. Always consult a healthcare professional before using clove oil, supplements, or any high-dose preparation, especially if you have existing health conditions or are taking other medications. Always prioritize your health by making informed decisions and being aware of the risks.

For more information on the hepatotoxicity of eugenol, consult the authoritative guide from the National Institutes of Health.

Eugenol (Clove Oil) - LiverTox - NCBI Bookshelf

Frequently Asked Questions

Consuming cloves in typical culinary amounts is considered safe and is unlikely to cause liver damage. The risk of liver toxicity is primarily associated with ingesting large, concentrated doses of clove oil or extracts.

Consuming cloves as a food spice is generally considered safe during pregnancy and breastfeeding. However, due to a lack of sufficient safety data, it is recommended to avoid medicinal or supplemental doses unless advised by a healthcare provider.

Clove oil is toxic when ingested, and children, particularly infants and toddlers, are extremely vulnerable. Their smaller body size and developing metabolism make them more susceptible to the toxic effects of eugenol, which can lead to severe liver damage and seizures.

Cloves can potentially lower blood sugar levels. While this might be beneficial for some, it poses a risk for individuals with diabetes who are already on medication, as the combined effect could cause hypoglycemia (low blood sugar).

Applying undiluted clove oil to your gums can cause significant irritation, a burning sensation, and tissue damage. It is toxic to human cells, and repeated use can harm the gum tissue and tooth pulp.

Cloves contain eugenol, which can interact with medications that slow blood clotting (anticoagulants like warfarin) and drugs used to manage diabetes. It is crucial to consult a doctor before using clove supplements if you are on these medications.

Allergic reactions to cloves or eugenol can include rashes, itching, hives, and swelling. In a severe reaction, anaphylaxis can occur, indicated by difficulty breathing, wheezing, and tightness in the throat. Seek immediate medical attention if this happens.

Yes, smoke from clove cigarettes is likely unsafe. It can cause respiratory problems, lung infections, and other health issues. Clove cigarettes often contain tobacco, which carries its own significant health risks.