Side Effects of Clove

Clove seems likely safe for most people when taken by mouth in food amounts. Not enough is known about the safety of taking clove by mouth in larger medicinal amounts.
Clove oil or cream containing clove flower is possibly safe when applied to the skin. However, frequent and repeated application of clove oil in the mouth or on the gums can sometimes cause damage to the gums, tooth pulp, skin, and mucous membranes.
Inhaling smoke from clove cigarettes or injecting clove oil into the veins is likely unsafe and can cause side effects such as breathing problems and lung infections.
Dried clove can also cause mouth sensitivity and irritation, as well as damage to dental tissues.

Special Precautions & Warnings:

Children: In children, clove oil is likely unsafe to take by mouth. It can cause severe side effects such as seizures, liver damage, and fluid imbalances.

Pregnancy and breast-feeding: Clove is likely safe when taken by mouth in food amounts. There is not enough reliable information about the safety of taking clove in medicinal doses if you are pregnant or breast-feeding. Stay on the safe side and avoid use.

Bleeding disorders: Clove oil contains a chemical called eugenol that seems to slow blood clotting. There is a concern that taking clove oil might cause bleeding in people with bleeding disorders.

Surgery: Clove oil contains a chemical called eugenol that seems to slow blood clotting. There is a concern that it might cause bleeding during or after surgery. Stop using clove at least 2 weeks prior to a scheduled surgery.

(Source: www.webmd.com)