Allspice does not contain any harmful ingredients, but may cause a moderate interaction with medications that reduce blood clotting. Allspice is a plant and its unripe berries are used to make medicine and in cooking.
Allspice is used medicinally for indigestion, intestinal gas, abdominal pain and emptying the bowels, according to WebMD.com. It does not contain any harmful ingredients, but it can moderately interact with blood-thinning medications because allspice may have the same effect. The interaction may increase risk of bruising or bleeding.
Allspice used in cooking is not harmful to humans. It is also not harmful to pets in small amounts, but in large amounts or in the form of essential oils, pets can experience diarrhea, vomiting or lowered blood sugar, according to Pet Poison Helpline.