Factoid: Holly Berry
Contributed by Division of Extension and Community Relations and the Department of Horticulture Science, University of Saskatchewan

Holly berries are potentially dangerous if eaten. Both the fruit and leaves contain a mixture of the caffeine-like alkaloid theobromine, caffeine itself, and glycosides. (Theobromine is also found in chocolate and cocoa.) In small doses these will stimulate the nervous system but in large doses they act as a depressant. North American native peoples of the southeast used the yaupon tree (Ilex vomitoria) to make a hallucinogenic beverage. The species name, vomitoria, comes from the fact that vomiting was a common side effect of its consumption.

In Europe, holly was once used in the treatment of such diverse problems as colic, fever, rheumatism, smallpox, and gout. An old English remedy for worms prescribes that a holly leaf and the top of a sage plant be placed in water; when the patient yawns over the dish, the worms drop out of his mouth.

Consumption of holly berries can cause vomiting and diarrheoa with drowsiness, coma, and death occurring in severe cases (which fortunately rarely happens). Twenty berries may constitute a lethal dose.