Herbs & Supplements

Should I take it?

Mistletoes are evergreen plants that exist as semi-parasites on apple trees, poplars, willows, and other trees that lose their leaves in winter. The plants actually root into the tree's branches or trunk and take water and minerals from the host tree. Mistletoe cannot be cultivated commercially. Although all mistletoe plants look similar, European mistletoe belongs to a different family of plants than the types of mistletoe that grow in North America. Mostly in northern Europe and Asia, European mistletoes bloom in the winter and produce small, waxy, white berries around the end of December. While the berries supply food for may types of birds, they are considered unsafe for humans to eat. The leaves and stems are collected to be used in medicine.

Because it stays green during the winter when most other plants look dead, European mistletoe was thought to have magical powers by ancient Britains and Scandinavians. Throughout the history of northern Europe, various medical properties have been associated with it. During the early part of the 20th century, European mistletoe became known as a cancer treatment, largely based on case reports. Even though more recent clinical studies in both laboratory animals and humans have shown only minimal effectiveness, European mistletoe is prescribed extensively in Germany and other European countries, usually in combination with conventional drugs, for cancer treatment.

Generally, oral forms of European mistletoe are less common than injectable forms. One reason is that European mistletoe has a narrow therapeutic range--a toxic dose is only slightly higher than the dose needed to treat a condition. Therefore, the exact dose that is effective for each patient is difficult to determine. Injections are easier to customize than oral doses are. Additionally, the amounts of active and harmful ingredients in both American mistletoe and European mistletoe differ according to the conditions under which it was grown, harvested, and processed. Reliable reports suggest that all types of mistletoe may accumulate toxic substances from their host trees. Because American mistletoe contains more potentially harmful chemicals than European mistletoe, American mistletoe should never be eaten or used for medicine.

Dosage and Administration

Note: Recommended doses of European mistletoe vary greatly. In general, the risk of side effects from using it increases as the dose increases.

European mistletoe is sold commercially as a supplemental oral extract in the United States as well as in many other countries. Extracts are concentrated liquid preparations usually made by soaking chopped or mashed plant parts in a liquid, and then straining out the solid parts. Dried extracts may be made into capsules or tablets. Individuals who decide to use an oral form of European mistletoe should purchase a commercial product from a reputable dealer and then follow the package directions for taking it. Due to possible toxicity, fresh European mistletoe leaves or berries should never be taken by mouth.

In Europe, where they are available as prescription medications, many different products containing European mistletoe are available with brand names such as Eurixor, Helixor, Iscador, Lektinol, and Vysorel. Because European mistletoe plants absorb different chemicals from different types of host trees, not all European mistletoe products may contain the same ingredients. In addition, European mistletoe may be prepared in different ways--some products are made from fermented European mistletoe, for example--which may affect their activity. Prescription European mistletoe extract usually is injected under the skin, into muscles, or into the abdominal cavity. However, it should be injected only in a medical facility and only by a health professional who has experience with its use. Injectable European mistletoe extract is not available in the United States.

Summary

Known mostly in northern Europe as an add-on treatment for cancer, European mistletoe may also affect heart function and increase immune response.

Risks

Women who are pregnant and individuals who are taking drugs to suppress their immune systems should avoid using European mistletoe. Heart conditions may be worsened by the use of mistletoe. Children under the age of 12 and women who are breastfeeding should not use mistletoe until more is understood about its effects.

Side Effects

Swallowing any part of the mistletoe plant may result in poisoning. Only commercial preparations of European mistletoe should be taken or injected. American mistletoe should not be used for medicine in any form. Orally, mistletoe may result in low blood pressure and gastrointestinal complaints such as diarrhea. If it is injected, European mistletoe may cause flu-like symptoms as well as itching or pain at the site of the injection.

Interactions

European mistletoe should not be used at the same time as drugs or herbals that affect heart function or drugs that decrease immune function.

Last Revised April 15, 2008