Juniper berries are used to add color and flavoring to pastry dishes, flavored teas and even some seasonal alcohols. However, the juniper berry can be poisonous to people with a low tolerance to volatile oils, such as thujone, according to the North Carolina State University Department of Horticulture.
The fleshy part of the berry contains the oily toxins of juniper berries. When eaten in large quantities, these berries can cause diarrhea and cramps, according to the Children's Hospital of Philadelphia.
You will notice the effects of juniper toxicity almost immediately. Some people may not have a reaction. Likelihood of symptoms increases if you eat larger quantities of berries. Small portions of berry extract in beverages will usually not lead to a reaction.
Juniper berries are poisonous to some people, but the poison is not lethal. Juniper berries are safe to eat for some people, but they may cause discomfort and short-term gastrointestinal problems.
Blackberries taste more tart than juniper berries, but they are a close substitute. Blueberries are sweeter but can also be used in most juniper berry recipes.