Thanks to its eugenol content, clove oil is a common anaesthetic, antiseptic and antifungal remedy. Its use as a dental pain reliever has its roots in 4th-century Europe, where, once the herb became widely available, cloves were used to treat toothache. But the eugenol in clove oil can go from treatment to toxin when misused, and the effects can be fatal.
General Internal Effects
Ingesting large amounts of undiluted clove oil can result in nausea and vomiting, sore throat, sedation, seizure or blood disorders. Difficulty breathing and even fluid in the lungs are possible.
Ingesting clove oil can also cause damage to, or failure of, the kidney and liver. Accordingly, people with kidney or liver disorders should avoid using clove oil at all.
Children are more susceptible to serious side effects of clove oil, even in small doses. For this reason, clove, clove oil and clove supplements should not be administered to children less than 2 years old or used by women who are pregnant or nursing.
Laboratory research indicates an increased bleeding risk associated with cloves and clove oil. Based on these findings, you should reduce the amount of clove oil you use medicinally, or avoid using it at all, if you have a bleeding disorder or if you are taking drugs, especially anti-coagulants, that increase your risk of bleeding. Also, if you have an operation scheduled, stop using clove oil before your surgery.
Effects in the Mouth
Undiluted clove oil in the mouth can cause a burning sensation, loss of sensation or tissue damage. Because clove oil can damage dental pulp, a higher risk of cavities is also possible.
Effects on Blood Sugar
Clove oil taken by mouth may lower blood sugar levels, so exercise caution if you have diabetes or hypoglycemia. Similarly, if you take drugs, herbs or supplements that affect blood sugar, you should be careful with clove oil, using less than you would or none at all. Monitor serum glucose levels for any change while taking clove oil.
Allergies to clove oil and other oils containing eugenol are not unheard of. Allergy symptoms include rash, itching and shortness of breath. Severe reactions such as anaphylaxis are possible. If you are allergic to clove oil, or if you experience hives in correlation with use of clove cigarettes, you should avoid using clove oil in any capacity.