European Mistletoe

Background

• European mistletoe is a semiparasitic plant that grows on several types of common trees such as apple, oak, pine, and elm. European mistletoe is different from American mistletoe, which is a type of mistletoe that grows in the United States and is used as a holiday decoration. 
• European mistletoe has been used for centuries in traditional medicine for a variety of conditions, including seizures, headaches, and menopause symptoms. Today, European mistletoe is promoted as a treatment for cancer.
• In Europe, European mistletoe extracts that are given by injection are sold as prescription drugs. European mistletoe may also be taken orally (by mouth) as a dietary supplement. The U.S. Food and Drug Administration (FDA) has not approved the use of European mistletoe as a treatment for cancer or any other medical condition.

How Much Do We Know?

• Although European mistletoe has been studied as a treatment for cancer, its effects are not well understood because much of the research has been of poor quality. Most studies have evaluated European mistletoe administered through injection by a health care provider. Very little research has looked at European mistletoe taken orally.

What Have We Learned?

• European mistletoe is not a proven cancer treatment. It should not be used as a treatment for cancer outside of clinical trials (studies in people).
• There have been clinical trials of European mistletoe for cancer treatment, mostly in Europe. Although some trials indicated that European mistletoe improved survival or quality of life, many of the trials had major weaknesses that raise doubts about their findings. These weaknesses have included small numbers of patients, lack of information about the patients, lack of information about the dose of European mistletoe, and problems with the design of the studies.
• The National Center for Complementary and Integrative Health and the National Cancer Institute performed a preliminary trial to evaluate the safety of injected European mistletoe extract in combination with a cancer drug in patients with advanced cancer. It showed that patients could tolerate the herb/drug combination.

What Do We Know About Safety?

• European mistletoe berries and leaves can cause serious harmful effects when taken orally.
• Injected European mistletoe extract may cause soreness and inflammation at the injection site, headache, fever, and chills. A few severe allergic reactions have been reported.
• If you take any type of medicine, talk with your health care provider before using European mistletoe or other herbal products; some herbs and medicines interact in harmful ways.
• European mistletoe is probably unsafe for use during pregnancy. Little is known about whether it’s safe for use while breastfeeding.

Keep in Mind

• Take charge of your health—talk with your health care providers about any complementary health approaches you use. Together, you can make shared, well-informed decisions.
• Federal Regulation of Herbal Products
  • Depending on what’s in them, how they’re intended to be used, and how they’re administered (orally or topically), herbal products are regulated in a variety of ways. Many herbal products intended for oral use are marketed as dietary supplements. The rules for making and distributing dietary supplements are less strict than those for drugs.
  • Unlike drugs, dietary supplements are not approved by the FDA before they are sold to the public. When public health concerns arise about the safety of a dietary supplement or an ingredient including an herb, the FDA can take action to protect the public. Manufacturers and distributors of supplements are responsible for evaluating the safety and labeling of their products before marketing to ensure that they meet all regulatory requirements. 

For More Information

• Using Dietary Supplements Wisely
• Know the Science: How Medications and Supplements Can Interact
• Know the Science: How To Make Sense of a Scientific Journal Article

Key References