Retrospective Study of Mistletoe Ingestion

Background: There are limited data concerning accidental exposure to Phoradendron flavescens (Phoradendron serotinum, American Mistletoe). The only published reports include a review of 14 cases which revealed no symptoms and a single fatality from an intentional ingestion of an unknown amount of an elixir brewed from the berries. The risk of serious toxicity from accidental exposure to this plant appears to be minimal, yet it continues to be regarded as a dangerous plant. We reviewed charts for four years (1990-1993) from three poison centers where Phoradendron flavescens is indigenous. Results: Ninety-two human cases were located. Age ranged from four months to 42 years, with a mean of six years (SD 8.8) and median of two years. There were 14 symptomatic cases of which 11 were determined to be related to mistletoe exposure. There were six gastrointestinal upset, two mild drowsiness, one eye irritation, one ataxia (21 months), one seizure (13 months). Treatments included gastrointestinal decontamination in 54 patients (59%), ocular irrigation in one and IV benzodiazepine in one. Decontamination did not appear to affect outcome. Amount ingested ranged from one berry or leaf to more than 20 berries or five leaves. In cases with a known amount ingested, eight of ten cases with ≥ 5 berries remained symptom free. In the 11 cases with leaf-only ingestion (range 1-5 leaves), three patients had gastrointestinal upset. The one case with five leaves ingested remained asymptomatic. The infant with seizures was an unwitnessed exposure, found with both berries and leaves in the crib. No arrhythmias or cardiovascular changes were reported in any case. All symptomatic cases had onset of symptoms in ≥ 6 hours. Discussion: Symptoms are infrequent and in all but one case would not require direct medical supervision. Seizures have not previously been reported with Phoradendron flavescens exposure. Conclusion: Symptoms from Phoradendron flavescens exposure are infrequent, even with ingestion of 5-20 berries or 1-5 leaves, but may include seizures. Cardiovascular efects were not seen.