After evaluating this article, participants will be able to:
1. Incorporate strategies into practice for the detection of toxicity associated with mistletoe ingestion
2. Develop an evidence-based approach to the management of mistletoe ingestions
A 2-year-old child is brought to the ED on a cold December evening by frantic parents one hour after swallowing several mistletoe berries at home. The parents had placed the mistletoe plant over the door entryway secured by a piece of scotch tape. During a large family holiday gathering, the mistletoe fell to the floor causing the curious toddler to ingest several of the scattered berries. When discovered by the mother, she gave her daughter a “bottle full” of outdated syrup of ipecac. En route to the ED, the child vomits twice in the family car.
In its natural setting, mistletoe is a semi-parasitic plant that uses its roots to penetrate a branch or trunk of a tree and absorb nutrients from its host. It is also capable of surviving on its own by producing food through photosynthesis. There are over 1000 species of mistletoe, but the species most commonly used for Christmas decoration is the American mistletoe (Phoradendron). It has greenish-yellow leathery leaves and white berries that first appear in the fall. American mistletoe grows on a wide variety of trees and ranges from Florida to New Jersey and as far west as Texas and California. American mistletoe berries are not intended for human consumption, but provide an essential food source for many birds, butterflies, insects, and mammals.
There is a rich heritage of folklore related to mistletoe. Both Norse and Greek mythology documented the plant’s mystical powers. The Celts worshiped mistletoe, especially when it was found on an oak tree. Our custom of decorating homes with mistletoe at Christmas is based on the Druid tradition of ushering in the winter solstice. During the Middle Ages, branches of mistletoe were hung from rafters to ward off evil spirits, and sprigs were placed above doorways to prevent witches from entering. Mistletoe was also believed to bestow fertility, and kissing under the mistletoe was associated with courtship and marriage. According to tradition, one berry should be removed from the sprig of mistletoe after each kiss. When all the berries are gone, the kissing would cease. Mistletoe has long been regarded as an aphrodisiac and fertility herb, which explains its association with uninhibited sexuality.
While kissing under the mistletoe is a longstanding holiday tradition, eating the plant is not recommended because mistletoe has a historic reputation of being poisonous. Eating any part of the plant, particularly the leaves or berries, or drinking a tea made from the plant, can result in clinical side effects. However, more modern studies have documented minimal toxicity.
The American Phoradendron species contains the toxin phoratoxin, which can cause blurred vision, nausea, abdominal pain, and diarrhea. The European Viscum species of mistletoe contains the alkaloid tyramine, which produces more pronounced symptoms than the American version including potential cardiotoxicity and hypotension following large exposures. Viscum album has some therapeutic uses including breast cancer treatment with Iscador, a drug made from mistletoe extract.
According to national poison control data, 1-2 berries or leaves eaten by a child will not result in serious toxicity. In studies with cases documenting accidental ingestion, there were no fatalities and very few symptomatic cases. One study published in 1996 reviewed 92 cases of mistletoe ingestion and found that only a small fraction of patients showed any signs or symptoms of toxicity. Eight of 10 people who consumed 5 or more berries had no symptoms, and 3 of the 11 people who consumed only leaves had self-limited GI symptoms. Another retrospective study reviewed over 1,700 exposures and found that accidental ingestion of American mistletoe was not associated with profound toxicity. One source recommends greater than 20 berries or 5 leaves should be referred for medical evaluation.
The child is evaluated in the ED with the following presenting vital signs: HR 120/min; BP 80/40mmHg; RR=28 breaths/min; T= 98 F; Pulse ox: 98% (RA)
The child has two more episodes of non-bloody emesis in the ED. Diagnostic studies return with the following values: WBC 13K; Hgb 14 gm/dL; Na 145 mEq/L; K 3.3 mEq/L Cl 108 mEq/L; Bicarb 21 mEq/L. The child is given a 20cc/kg intravenous fluid bolus and ondansetron for protracted emesis. After six hours of ED observation, she recovers uneventfully. The parents are counseled regarding poison prevention in the home and instructed that syrup of ipecac is no longer recommended as a gastric decontamination agent in the home or hospital setting.
Timothy Erickson, MD, FACEP, FACMT is a Professor of Emergency Medicine and Medical Toxicology at the University of Illinois at Chicago. He is also Director of the UIC Center for Global Health.
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