As for your pets, the American Veterinary Medicine Association of America (AVMA), does not include poinsettias on its list of plants that are a threat to animals. The ASPCA states that ingestion of poinsettias may cause mild to moderate gastrointestinal tract irritation, which may include drooling, vomiting and/or diarrhea–but nothing severe or fatal.
Mistletoe, on the other hand? Not so innocent. Mistletoe may inspire spontaneous smooching, as well as gastrointestinal distress, a slowed heartbeat and other reactions if ingested due to the presence of harmful chemicals like viscotoxins. Although not thought to be fatal, it can cause severe reactions. In pets, mistletoe may cause astrointestinal disorders, cardiovascular collapse, dyspnea, bradycardia, erratic behavior, vomiting, diarrhea, and low blood pressure. Ouch! So keep the mistletoe securely fastened above your door, but fear the poinsettia no more.