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Poinsettias, mistletoe, and holly not as poisonous as once feared

The red berries from holly and the sap from poinsettia plants can cause discomfort if ingested.
Wendy Murray
The red berries from holly and the sap from poinsettia plants can cause discomfort if ingested.
AFP/Getty Images

Parents have long worried that three of the most popular plants decorating American homes during the Christmas season — mistletoe, holly, and poinsettias — are poisonous, and can even be deadly if ingested. Relax, just a little: New medical evidence suggests these fears are exaggerated.

A recent analysis of data from the American Association of Poison Control Centers shows that ingestions of berries or flowers are mostly harmless, and that there are far greater dangers parents should be mindful of during the holidays, like glasses of alcohol lying around during a party, small batteries from newly opened toys, and a guest’s medications carelessly left around the house.

“Treating a poinsettia exposure is a glass of milk for the child and a tincture of reassurance for the parent, that’s it,” said Dr. Ed Krenzelok, managing director of the Pittsburgh Poison Center, in a statement.

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That’s not to say they are harmless. Mistletoe berries contain phoratoxin, a chemical that can cause nausea, vomiting, diarrhea, and abdominal pain. In high enough doses, it can lead to arrhythmias and death, but that would require eating at least 20 berries.

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Krenzelok, who has studied poisoning incidents from Christmas plants for more than 20 years, analyzed almost 27,000 poisonings involving mistletoe, holly, and poinsettias, and found that roughly 90 percent of the patients had no symptoms and that almost all the others had only mild discomfort. Only 30 individuals, or 1/10th of 1 percent of the total sample, became seriously ill.

Krenzelok says that since 1983 the American Association of Poison Control Centers has not recorded a single death due to accidental exposure to these plants. There are isolated reports of deaths due to mistletoe, he said, but they invariably involved individuals who tried to brew tea from the plant for its supposed health benefits.

The red berries found on boughs of holly contain saponins, a class of molecules similar to the heart drug digitalis. In high enough doses they, too, can cause vomiting, stomach pain, and diarrhea. Holly also contains theobromine, which is in the same chemical family as caffeine or the asthma medication theophylline. Theobromine is not dangerous to humans but can cause seizures and arrhythmias in dogs and cats that are unable to metabolize the enzyme.

The poinsettia flower is harmless, but its latex sap can cause irritation to the skin or stinging if rubbed in the eye. If eaten, it could also irritate the stomach lining.

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David Fiske, gardens curator of the Massachusetts Horticultural Society, says berries are generally removed from mistletoe that’s sold in garden centers in the northeast. In other words, shoppers have no contact with the potentially toxic berries, unless they choose to pick plants growing wild.

Krenzelok says parents should be more worried about small toys, dice from games, marbles, and tiny batteries that can all be choking hazard for a child. “I’m always concerned about airway obstruction hazards,” he says. Batteries are especially dangerous because they contain sodium or potassium hydroxide, which can damage the tissue of the esophagus when swallowed.

Leftover adult drinks are another often-overlooked hazard. Mixed with sugary sodas or brightly colored fruit juices, drinks such as vodka, gin, and whisky can make an appealing target for kids. But even small amounts of alcohol can be devastating to infants and small children because it can cause a rapid drop in blood sugar, followed by seizures and coma.

There is another family member to be mindful of, as well, during the holidays: the family pet. Rob Halpin, a spokesman for the Massachusetts SPCA, said mistletoe and holly can make dogs and cats nauseous and lethargic.

But as with humans, other seasonal plants and foods pose a bigger risk. Pets should be kept away from chocolate, macadamia nuts, grapes, and raisins all year long, Halpin says. Lilies are highly toxic to cats and produce kidney failure even in small doses. Their impact is much more severe and long lasting. “The other Christmas plants,” he adds, “are just going to cause some upset stomach in most cases.”

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Halpin recommends that holiday decorations be set up in a room easily shut off from pets. Krenzelok added that the best advice is to keep potentially dangerous objects out of children’s reach. Parents should go through the house on hands and knees to get a sense what a 2-year old is likely to see and touch.

‘Treating a poinsettia exposure is a glass of milk for the child and a tincture of reassurance for the parent, that’s it.’

If a child does accidentally eat a poisonous leaf or berry, parents should first call the National Capital Poison Center at 800-222-1222. Most cases do not require medical attention and can usually be handled over the phone. “The poison center will undoubtedly give you good advice,” Krenzelok says, “and prevent an unnecessary trip to the emergency department over the holidays when that’s the last thing you want to do.”

Chris Labos is a physician and a Global Journalism Fellow at the Munk School in the University of Toronto.