Cloves (Syzygium aromaticum) are a popular spice used in kitchens around the world and have a long history in traditional herbal practices. They are valued for their distinctive aroma, antioxidant content, and naturally occurring compound eugenol, which has been studied for a variety of biological effects.

However, it’s important to remember that natural does not always mean risk-free. Like many herbs and spices, cloves can cause side effects or interact with certain medications when consumed in large amounts, used for extended periods, or taken in concentrated forms such as essential oil.

In this article, you’ll learn about nine potential side effects of cloves, who should be cautious, and how to use them safely.

Why Can Cloves Cause Side Effects?

The primary active compound in cloves is eugenol, a natural substance responsible for much of the spice’s characteristic aroma and many of its biological properties.

Eugenol may influence several body systems, including:

The digestive system
Blood clotting
Liver metabolism
The nervous system

While these effects may contribute to cloves’ traditional uses, they also explain why moderation is important.

1. Digestive Irritation

Eating excessive amounts of cloves may irritate the digestive tract.

Some people may experience:

Heartburn
Stomach discomfort
Nausea
Abdominal pain

Digestive irritation is more likely if cloves are consumed on an empty stomach or by individuals with sensitive digestive systems.

2. Liver Concerns with Excessive Intake

Eugenol is processed by the liver.

Although small culinary amounts are generally considered safe for healthy adults, very large doses, particularly from concentrated products like clove oil, have been associated with liver toxicity in medical reports.

People with existing liver disease should consult a healthcare professional before using clove supplements or essential oils.

3. Increased Bleeding Risk

Some research suggests that eugenol may influence blood clotting.

For this reason, people taking medications such as:

Warfarin
Apixaban
Rivaroxaban
Aspirin
Clopidogrel

or those scheduled for surgery should speak with their healthcare provider before consuming large amounts of cloves or using clove supplements.

Using cloves as a normal culinary spice is generally not considered problematic for most people.

4. May Affect Blood Sugar Levels

Some studies suggest cloves may influence glucose metabolism.

While this area continues to be researched, people with diabetes who use glucose-lowering medications should be aware that combining herbal supplements with prescription treatment could increase the risk of low blood sugar (hypoglycemia).

Possible symptoms include:

Dizziness
Sweating
Weakness
Confusion
Shakiness

Never adjust diabetes medication without medical supervision.

5. Mouth and Gum Irritation

Many people chew whole cloves to freshen breath or temporarily soothe tooth discomfort.

However, frequent or excessive use may cause:

Burning sensations in the mouth
Gum irritation
Temporary numbness
Oral tissue sensitivity

Persistent dental pain should always be evaluated by a dentist rather than treated solely with home remedies.

6. Allergic Reactions

Although uncommon, some individuals may be allergic to cloves or clove oil.

Possible symptoms include:

Itching
Skin rash
Swelling of the lips or mouth
Difficulty breathing (in severe cases)

Anyone experiencing signs of a serious allergic reaction should seek immediate medical attention.

7. Pregnancy and Breastfeeding Precautions

Using cloves in normal food amounts is generally considered acceptable during pregnancy.

However, high-dose supplements or clove essential oil should be avoided unless recommended by a qualified healthcare professional, as there is insufficient evidence to confirm their safety during pregnancy or breastfeeding.

8. Potential Medication Interactions

Cloves may interact with certain medications, including those used for:

Blood thinning
Diabetes
Blood pressure management
Liver conditions

If you take prescription medications or have a chronic medical condition, consult your healthcare provider before regularly using clove supplements or medicinal preparations.

9. Clove Essential Oil Can Be Toxic

Clove essential oil is highly concentrated and should be used with extreme caution.

Improper use may lead to:

Poisoning if swallowed
Severe irritation or burns to the skin and mucous membranes
Liver damage with excessive ingestion
Serious health risks in children

Never consume clove essential oil unless specifically instructed by a qualified healthcare professional.

Essential oils should also be properly diluted before topical use and kept out of reach of children.

How to Use Cloves Safely

To enjoy cloves while minimizing potential risks, consider these practical guidelines:

Use cloves in moderate amounts when cooking or preparing tea.
Limit prolonged use of concentrated clove supplements unless advised by a healthcare professional.
Avoid swallowing clove essential oil.
Dilute essential oil appropriately before applying it to the skin.
Stop use if you experience signs of an allergic reaction or digestive discomfort.
Consult your healthcare provider if you are pregnant, breastfeeding, taking prescription medications, or managing a chronic illness.