by David Moore
Manager of Technical Services and Board Certified Entomologist
with contributions by Eric Smith, PhD, BCE
Since this is a very important concern of many people, it bears repeating from last December. Probably like you, I was brought up with the belief that poinsettias and mistletoe were very poisonous and that ingestion and close contact should be avoided. There was special concern for small children and pets. Well, a lot has been learned in the past several years about their toxicity to humans and pets.
A brief history
Apparently the claim of their toxicity goes back to 1919, when an army officer’s two-year-old child reportedly died after eating part of a poinsettia leaf (bract). This claim is now is question because of the many reports of poinsettia ingestion with the end result being only mild symptoms such as nausea or vomiting, but no deaths.
In 1996, a detailed analysis of some 22,000+ cases of ingestion of poinsettia was published in the American Journal of Emergency Medicine. This revealed no deaths, that 96% of the cases required no treatment outside of the home, and 92% of the people developed no symptoms after ingestion. There has been one estimate that a 50-pound child would have to consume more that 500 leaves to approach a dose that could cause symptoms to appear.
What about pets?
Dogs and cats that ingest poinsettias may suffer gastrointestinal symptoms. However, apparently these plants pose no major threat to pets.
A brief history
Mistletoe has been used for centuries as a treatment for arthritis, infertility, high blood pressure, and headache. However, American mistletoe is generally considered to be very toxic by both the lay public and many medical professionals despite that there is no data to support this contention.
In 1997, a paper was published in the American Journal of Emergency Medicine in which the authors examined the outcomes of 1,754 exposures to this plant based on data collected during 1985-1992 by the American Association of Poison Control Centers. Exposures to children accounted for 92.1% of the cases, and 94.7% of these were from accidental exposures. They found that 99.2% of these cases had an outcome associated with no disease, and there were no deaths. They concluded that the accidental ingestion of American mistletoe is not associated with profound toxicity.
In another paper published in 1996 in the Journal of Toxicol Clinical Toxicology, the authors examined data associated with 92 human cases collected from 1990-1993, of which only 14 had any symptoms. In the cases of a known quantity ingested, 8 of 10 where 5 or more berries (range up to 20 berries) were ingested, they remained symptom free. In the 11 cases with leaf-only ingestion (range of 1-5 leaves), 3 patients had gastrointestinal upset and the one case of 5 leaves ingested had no symptoms. Symptoms appeared in 6 hours or less in the cases where symptoms appeared.
They concluded that symptoms from exposure are infrequent, even with the ingestion of 5-20 berries or 1-5 leaves, and rarely require direct medical supervision. However, they did find one case of seizures in a 13-month-old infant where the consumption was not witnessed but berries and leaves were found in the infant’s crib.
Poinsettias and American mistletoe are not extremely toxic to humans or pets when ingested. Ingestion of low to moderate quantities of berries or leaves rarely results in symptoms, and symptoms are usually mild.
Most exposures are accidental and involve children. And, pets usually avoid these plants after a quick taste. So, it is prudent to position these plants such that they are not easily accessible to children and pets.
Have and enjoy these beautiful traditional holiday plants!