Poinsettia plants are mildly toxic, but they are not deadly. The worst symptoms of poinsettia poisoning are stomach and mouth irritation. In some cases, enough leaves are consumed to cause vomiting.
A study in the American Journal of Emergency Medicine found that there were no fatalities in children in 22,793 cases of poinsettia ingestion and more than 92 percent of the patients had no reaction at all. An earlier study showed no fatalities in animals exposed to poinsettia sap. Temporary blindness is possible if sap gets into the eye, but it clears up quickly. The myth of poisonous poinsettias started in 1919 after a report a small child died after ingesting a poinsettia leaf.