The answer is: it depends on the type of mistletoe and what part you eat. There are several species of mistletoe. The Phoradendron species contain a toxin called phoratoxin, which can cause blurred vision, nausea, abdominal pain, diarrhea, blood pressure changes, and even death. The Viscum species of mistletoe contain a slightly different cocktail of chemicals, including the poisonous alkaloid tyramine, which produce essential the same symptoms. Although mistletoe has therapeutic uses, eating any part of the plant (particularly the leaves or berries) or drinking a tea from the plant can result in sickness and possibly death. Unlike the holiday poinsettia, which has a bad reputation yet probably won't do more than make you feel sick if you eat it, mistletoe ingestion warrants a call to Poison Control and immediate medical attention.