Dr. Albert, DDS, (USA)
Oil of cloves, also Clove oil, is an essential oil from the clove plant. It is a natural analgaesic used primarily in dentistry for its active ingredient eugenol. It can also be purchased in pharmacies over the counter, as a local anaesthetic for dental pain relief, mainly toothache; it is also often found in the aromatherapy section of health food stores. The oil produced by cloves can be used in many things from flavouring medicine to remedies for bronchitis, the common cold, a cough, fever, sore throat and tending to infections. Its country of origin is India.
Oil of cloves is known best for its anaesthetic properties. It is widely reported to be effective, and prior to the availability of safe, approved topical anaesthetic drugs, was used by some dentists. It is considered safe in very small quantities (<1500 p.p.m.) as a food additive.  However, clove oil is highly toxic to human cells at relatively low (.03% v/v) concentrations.  It is unapproved for any topical or oral use in the United States. If ingested in sufficient quantity or injected, it has been shown to cause life-threatening complications, including Acute Respiratory Distress Syndrome, Fulminant Hepatic (Liver) Failure, and Central Nervous System Depression.