Cloves, the dried flower buds of the Syzygium aromaticum tree, are prized for their unique flavor and aromatic properties. They contain a potent active compound called eugenol, which is responsible for many of the spice's purported health benefits but also its potential for harm. While typically safe when consumed as a spice in small, culinary amounts, concentrated forms like clove oil or excessive intake can lead to serious health complications.
Potential Health Risks of Excessive Clove Use
Liver Toxicity and Organ Damage
One of the most significant dangers associated with high-dose clove use, especially concentrated clove oil, is the risk of liver damage. Eugenol, a cytotoxic compound in high concentrations, has been linked to severe acute liver and kidney injury in overdose cases, with children being particularly vulnerable. Overdoses often present with agitation, decreased consciousness, and liver abnormalities that appear within hours of ingestion. In infants who have accidentally swallowed clove oil, life-threatening complications like liver failure and seizures have been reported.
Blood-Thinning Properties
The eugenol in cloves has been shown to slow blood clotting. This can be particularly dangerous for individuals who have bleeding disorders or are taking anticoagulant (blood-thinning) medications like warfarin, aspirin, or ibuprofen. Combining cloves with these drugs can increase the risk of bruising and excessive bleeding. For this reason, it is often recommended to stop using clove products at least two weeks before a scheduled surgery to avoid potential complications with blood clotting.
Drug Interactions and Hypoglycemia
Beyond blood thinners, cloves can interact with other medications. Their ability to lower blood sugar levels means that taking clove supplements alongside diabetes medication could cause hypoglycemia (dangerously low blood sugar). People with diabetes should monitor their blood sugar closely and consult a healthcare provider before using clove medicinally. Cloves can also affect how the liver breaks down certain medications, potentially altering their effects and side effects.
Allergic Reactions and Skin Irritation
Some individuals may have an allergic reaction to cloves, with symptoms such as itching, rash, swelling, or difficulty breathing. Inhaling powdered cloves can also irritate the nasal passageways. Clove oil, in particular, is a known skin and mucous membrane irritant. Applying undiluted clove oil directly to the skin can cause burning, rashes, and contact dermatitis. Prolonged or excessive use inside the mouth, even for dental pain relief, can cause irritation and gum damage.
Gastrointestinal Issues
High doses of cloves or clove oil can irritate the digestive tract, leading to issues like nausea, vomiting, heartburn, and diarrhea. While often used for digestive health in small amounts, excessive consumption can have the opposite, negative effect. Swallowing concentrated clove oil is particularly dangerous and can lead to severe gastrointestinal discomfort.
Respiratory Problems from Clove Cigarettes
Smoking clove cigarettes (kreteks) is associated with serious respiratory problems and is considered unsafe. Inhaling clove smoke can lead to a range of lung injuries, including hemorrhagic pulmonary edema, bronchitis, and pneumonia. This is a distinct risk associated with smoking the spice rather than consuming it in food or as a supplement.
Clove vs. Clove Oil: A Critical Comparison
There is a major difference in potency between whole or ground cloves used in cooking and concentrated clove oil. This table highlights key differences regarding their side effects and safety profile.
| Feature | Culinary Cloves (Whole or Ground) | Concentrated Clove Oil |
|---|---|---|
| Eugenol Concentration | Low and generally safe in food amounts. | Highly concentrated, with eugenol levels up to 89%. |
| Risk of Toxicity | Very low risk; requires excessive, long-term consumption. | High risk, especially if ingested or used improperly. Can be toxic to the liver and kidneys. |
| Effect on Blood Clotting | Minor effect in typical culinary quantities. | Can significantly slow blood clotting, increasing bleeding risk. |
| Effect on Blood Sugar | Modest effect, primarily noted in supplementary doses. | Can cause a dangerous drop in blood sugar levels (hypoglycemia). |
| Topical Application | Not typically used topically. | Can cause severe skin irritation, burns, and damage to oral tissues if undiluted. |
| Usage Precautions | Caution with large, supplemental quantities and during surgery. | Must be handled with extreme care, properly diluted, and kept away from children. |
Conclusion
While cloves offer various culinary and potential health benefits, understanding what are the side effects of using cloves is essential for safe use. Most adverse effects are associated with the high concentration of eugenol found in clove oil or with excessive, long-term consumption of supplements. Risks include liver damage, blood-thinning complications, allergic reactions, and digestive distress. Individuals on certain medications, those with bleeding disorders or diabetes, and especially children, should exercise extreme caution. Always consult a healthcare provider before using cloves for medicinal purposes or taking clove supplements to ensure it is safe for your individual health profile. For general cooking, cloves remain a safe and flavorful spice when used in moderation.
For more detailed information on eugenol and its effects, the U.S. National Institutes of Health provides comprehensive research.
What are the Side Effects of Using Cloves? A Summary
- Liver Toxicity: High doses of concentrated clove oil can cause severe liver and kidney damage, particularly in children.
- Blood-Thinning: The eugenol in cloves can slow blood clotting, posing a risk for individuals with bleeding disorders or those taking anticoagulant medications.
- Hypoglycemia Risk: High-dose clove intake can dangerously lower blood sugar, a concern for people with diabetes or those on diabetes medication.
- Skin and Oral Irritation: Undiluted clove oil can cause burning, rashes, and damage to sensitive tissues when applied topically or to the gums.
- Allergic Reactions: Some people may be allergic to cloves, experiencing symptoms ranging from skin rashes to breathing difficulties.
- Gastrointestinal Distress: Excessive consumption of cloves or clove oil can lead to nausea, vomiting, and diarrhea due to digestive tract irritation.
- Respiratory Issues: Smoking clove cigarettes has been linked to severe lung diseases and is considered unsafe.
- Drug Interactions: Cloves can interfere with various medications by altering how the liver processes them, potentially changing their effectiveness.
