Other common name(s): European mistletoe, all heal, bird lime, devil's fuge, golden bough, Iscador, Eurixor, Helixor, Isorel, Iscucin, Plenosol, and Abnoba viscum
Scientific/medical name(s): Viscum album, Viscum coloratum
Mistletoe is a semi-parasitic plant that grows on a number of species of trees native to Great Britain, Europe, and western Asia. It is different from the mistletoe found in the United States. The plant’s leaves and twigs are used in herbal remedies; the berries are not used. There are hundreds of different mistletoe species throughout the world. This discussion covers only European mistletoe unless otherwise noted.
A number of laboratory experiments suggest European mistletoe may have the potential to help treat cancer, but these results have not yet been reflected in clinical trials. Available evidence from well-designed clinical trials does not support claims that mistletoe can improve length or quality of life.
How is it promoted for use?
Proponents claim that mistletoe stimulates the immune system, helping the body fight more efficiently against cancer and other diseases. Mistletoe extracts are promoted as a remedy for many types of cancer, including cancer of the cervix, ovaries, breast, stomach, colon, lung, and as a treatment for leukemia, sarcoma, and lymphoma. Supporters claim mistletoe extract injected directly into or near a tumor can slow and possibly reverse the growth of cancer cells, even in advanced cases of cancer.
Promoters also claim mistletoe can lower blood pressure, decrease heart rate, relax spasms, and relieve symptoms of arthritis and rheumatism. It is further claimed to have sedative effects and is promoted to relieve the side effects of chemotherapy and radiation therapy.
What does it involve?
Commission E, Germany's regulatory agency for herbs, has approved mistletoe injections as palliative therapy (treatment that is intended to treat symptoms, not cure disease) for malignant tumors. The herb is prepared as a whole plant extract to be injected and is not taken by mouth. The plant itself is poisonous and is not safe to eat. Mistletoe extracts are injected under the skin near the tumor. Daily injections are often given before and after surgery, chemotherapy, or radiation therapy and may continue for 10 to 14 days. Mistletoe injections promoted to prevent cancer may involve 3 to 7 injections a week over several months to several years.
There are mistletoe preparations sold as homeopathic medicines in the United States. For more, see our information on Homeopathy.
What is the history behind it?
Mistletoe is surrounded by fascinating myths and legends dating back many centuries. More than 2,000 years ago, the Druids (members of the educated class among the ancient Celts in Europe) used mistletoe in many religious rituals. Their name for mistletoe meant “all healer,” because they believed it had magical powers. The tradition of kissing under mistletoe dates back to a Scandinavian myth in which the plant becomes a symbol of love.
The liquid extract of the mistletoe plant has been used as an alternative method to treat cancer for close to a century. Modern research on mistletoe began in 1916 with Rudolph Steiner, PhD. Steiner combined spiritual and scientific approaches to medicine and to the treatment of cancer in particular. He believed that cancer formed when regulation of the body's physical or spiritual defenses faltered, and that mistletoe could re-establish that regulatory balance and help fight the tumor. Later researchers carried Steiner’s beliefs further, contending that some of the chemicals in mistletoe could stop cancer growth and even kill cancer cells directly while enhancing the body's immune system.
Mistletoe injections are currently among the most widely used unconventional cancer treatments in Europe. Physicians in Switzerland, the Netherlands, and Great Britain commonly prescribe the treatment. In Europe, the most common commercial preparations are sold under the trade names Iscador and Helixor. Only the European species of the mistletoe plant is used for cancer treatment. Mistletoe injections are not available in the United States, except in clinical trials, because the drug is not approved for sale by the US Food and Drug Administration (FDA).
What is the evidence?
Mistletoe preparations vary widely depending on how they are made (for instance, whether they are extracted with water or alcohol solutions, fermented or non-fermented), the particular species from which they are obtained, and the season in which the plant was harvested. Researchers are working to identify the most important components in mistletoe, though they are thought currently to be the lectins, or proteins. A number of laboratory experiments have suggested that mistletoe extracts may have some potential to kill cancer cells, but these results have yet to be reflected in human trials.
Researchers have completed numerous studies of mistletoe and its effects on cancer. A careful 2008 review of available clinical evidence concluded that the studies that reported improved survival in people with cancer had flaws in their scientific design, and their results could not be considered dependable. The more carefully controlled human clinical studies have indicated that mistletoe does not have any significant effect on survival of people with cancer.
Two scientifically sound clinical trials of mistletoe suggested that mistletoe might improve quality of life among people with cancer, although positive conclusions were reported from many other studies that appeared to be flawed. Some studies are still underway, but most are not randomizing the volunteers, which means that results cannot be considered very useful due to potential pre-existing differences in the treated and control groups. More rigorous research studies are needed.
Are there any possible problems or complications?
In recommended doses, purified mistletoe extract is generally considered safe. Possible side effects include temporary redness at the injection site, headaches, fever, and chills. Rarely, in people allergic to mistletoe, a severe and potentially life-threatening condition called anaphylactic shock can develop.
Potentially dangerous interactions with conventional medicines are possible, particularly with some medications that are used for high blood pressure, irregular heart rhythm, and heart failure. Always tell your doctor and pharmacist about any herbs you are taking.
The European mistletoe plant should not be eaten because all parts of it are poisonous. Consuming mistletoe has been reported to cause seizures, coma, and death. Other symptoms of mistletoe toxicity include blurred vision, nausea and vomiting, stomach pain, diarrhea, slow or irregular heartbeat, low blood pressure, confusion, and drowsiness.
American mistletoe is considered less toxic but it can still cause upset stomach and other symptoms if it is eaten. One death has been reported in a person who drank a brew of mistletoe berries. Because of their smaller size, children or pets might be harmed by lesser amounts.
Allergy to mistletoe is rare, but can be serious. Women who are pregnant or breast-feeding should not use any form of this herb.
Relying on this type of treatment alone and avoiding or delaying conventional medical care for cancer may have serious health consequences.
To learn more
More information from your American Cancer Society
The following information on complementary and alternative therapies may also be helpful to you. These materials may be found on our Web site (www.cancer.org) or ordered from our toll-free number (1-800-227-2345).
The ACS Operational Statement on Complementary and Alternative Methods of Cancer Management
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Note: This information may not cover all possible claims, uses, actions, precautions, side effects or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for consultation with your doctor, who is familiar with your medical situation.
Last Revised: 01/16/2013