Is Mistletoe Really Poisonous?

Learn About Mistletoe Toxicity

There are several species of mistletoe. Some species are quite toxic.
There are several species of mistletoe. Some species are quite toxic. Anna Yu, 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?

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. 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.

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.

The Bottom Line

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.