Are Olive Trees Poisonous to Animals?

The Oleaceae family includes several plants, the Mediterranean olive tree being one, that grow in the United States. Some of these species include poisonous parts that may be dangerous to animals and humans.

Mediterranean Olive Trees

The olive tree produces the edible olives and oil used throughout the world, with the majority originating from the Mediterranean area. The only member of the Oleaceae family that produces edible fruit, its olives must be processed to remove the bitterness caused by a glucoside.

Oleaceae Family

This family includes many non-toxic plants such as ash trees and lilacs, but also poisonous ones like privet. A woody, deciduous shrub, both the foliage and berries of privet are poisonous. Effects include stomach upset and pain, vomiting and even death, thought to be caused by an unidentified glycoside.


Poisoning from toxic plants in this family occur only rarely, according to the University of Pennsylvania. Documented cases in the past include sheep, horses, cattle and children as victims.


Omphalotus olearius, commonly known as Jack-O-Lantern mushrooms, commonly grow on olive trees. These glow-in-the-dark mushrooms are poisonous, causing a wide variety of symptoms including abdominal pain, headache, fatigue, a feeling of cold, dizziness and diarrhoea. Internal bleeding occurs in limited cases as well. Since they grow on olive trees, it is possible that some people mistakenly assume such poisoning to be the result of the olive tree itself.