Is Mistletoe Really Poisonous?

Learn About Mistletoe Toxicity

Sprig of mistletoe close up.
There are several species of mistletoe, and some are toxic.

Jacky Parker Photography/Moment/Getty Images

While kissing under the mistletoe is perfectly acceptable, eating the plant or its berries is not a good idea. Is mistletoe really poisonous? Many of us know someone who ate a berry or two as a kid and lived to tell the tale. Were they just lucky or is it okay to eat a few berries?

Key Takeaways

  • There are multiple species of mistletoe. All of them produce toxic compounds.
  • The leaves and berries contain the highest concentration of dangerous chemicals.
  • Most adults can eat a few berries without harm, but children and pets are at risk of poisoning.
  • Mistletoe is used to treat high blood pressure and cancer.

Toxic Chemicals in Mistletoe

The answer is that the risk of poisoning depends on the type of mistletoe and what part of the plant is eaten. There are several species of mistletoe. All are hemiparasitic plants that grow on host trees, such as oak and pine. The Phoradendron species contain a toxin called phoratoxin, which can cause blurred vision, nausea, abdominal pain, diarrhea, blood pressure changes, and even death. The Viscum species of mistletoe contain a slightly different cocktail of chemicals, including the poisonous alkaloid tyramine, which produce essentially the same symptoms.

The leaves and berries contain the highest concentration of toxic chemicals. Alternatively, drinking a tea from the plant can result in sickness and possibly death. That being said, the average healthy adult can tolerate a few berries. The risk of poisoning is higher for children and particularly for pets. Most of the risk comes from the effect the proteins in the plan have on the cardiovascular system.

Therapeutic Uses of Mistletoe

Although mistletoe can be dangerous, it also has therapeutic uses. The plant has been used medicinally in Europe for hundreds of years to treat arthritis, high blood pressure, epilepsy, and infertility. However, it's important to remember the species in Europe (Viscum album) is less toxic than the species found in America (Phoradendron serotinum). Some studies indicate mistletoe may be useful in treating cancer, although further evidence is needed. According to the National Cancer Institute, mistletoe extract has been demonstrated to affect the immune system and kill cancer cells in the laboratory. It may also decrease side effects of radiation and chemotherapy. However, its use is not approved by the FDA.

While mistletoe is not used in the United States, an injectable form of the plant is available in Europe as an adjuvant cancer therapy. Mistletoe tea and berries made in tea may be used to treat hypertension at a dose of 10 g/day. For the most part, mistletoe therapies are used in healthy adults, although there are reports of successful use in pediatric patients. The plant is not recommended for patients who have leukemia, brain tumors, or malignant lymphoma or for lactating or pregnant women. Mistletoe is also used in veterinary herbal medicine.

The Bottom Line

European mistletoe ingestion has caused cases of poisonings and sometimes deaths. However, American mistletoe isn't as toxic. A study of 1754 American mistletoe exposures revealed none resulted in death, even though 92% of the cases involved children. Another study of 92 cases reported to poison control centers revealed no cases of death, even though up to 20 berries and 5 leaves were eaten. In one case, a child suffered a seizure, but researchers were unable to definitively link it to mistletoe consumption.

Eating one or a few berries is unlikely to cause sickness or death. However, anaphylactic reactions are known, so it's important to watch for indications of a reaction to the plant. Consumption of a large number of berries is extremely dangerous and warrants a call to Poison Control. The number for Poison Control is 1-800-222-1222.

Sources

  • Hall, A.H.; Spoerke, D.G.; Rumack, B.H. (1986). "Assessing Mistletoe Toxicity." Ann Emerg Med. 11:1320-3.
  • Horneber, M.A., Bueschel. G.; Huber, R.; Linde, K.; Rostock, M. (2008). "Mistletoe therapy in oncology." Cochrane Database Syst Rev (Systematic review) (2): CD003297.
  • Krenzelok, E.P.; Jacobsen, T.D.; Aronis, J. (1997). "American Mistletoe Exposures." Am J Emerg Med. 15:516-20.
  • Spiller, H.A.; Willias, D.B.; Gorman, S.E.; et al. (1996). "Retrospective Study of Mistletoe Ingestion." J Toxicol Clin Toxicol. 34:405-8.
  • Suzzi, Giovanna; Torriani, Sandra (2015). "Editorial: Biogenic amines in foods." Frontiers in Microbiology. 6: 472. doi:10.3389/fmicb.2015.00472