Mistletoe (Viscum album)

Mistletoe is a plant that grows on trees such as apple, pine, oak, and elm. It is also called iscidor, helixor, and isorel. Scientifically, it is known as viscum album. It is a semiparasitic plant because it can take in nutrients from its host plant.

There are many types of mistletoe. The most well-known is the Western European version, which has rounded, emerald leaves and white berry clusters with 2 – 6 berries. The Eastern European version can have as many as 10 berries and shorter, broader leaves.

Historical Uses

Mistletoe was used as a cure for poisons and to treat infertility and constipation. It has cultural meaning, as some Cornish customs made replicas of the cross from mistletoe. There is also the act of kissing someone if you are both "under the mistletoe.”

Current Uses

Mistletoe has been used for many years in European countries as a complementary cancer treatment. Researchers believe it fights cancer by stopping the creation of blood vessels that help cancerous tumors grow. Research has also shown that mistletoe can play a role in killing cancer cells and changing how the immune system works. Mistletoe may also lower the side effects of chemotherapy and radiation therapy and improve quality of life.  The U.S. Food and Drug Administration (FDA) has not approved the use of mistletoe for any medical purpose. It is offered in many integrative care settings in the United States.

What parts are used and how are they given?

Mistletoe extracts depend on things like:

• The kind of mistletoe plant used.
• How it is prepared.
• The time of year it is grown and harvested.

Mistletoe extracts are most often given by injection under the skin. Sometimes it is given into a vein (IV), the pleural cavity (space between the lungs), or directly into a tumor. 

Side Effects and Safety Concerns of Herbal & Nutritional Supplements

Side effects differ based on the type of mistletoe used. Raw mistletoe leaves, branches, and berries are poisonous and should not be eaten. Mistletoe can cause stomach pain, diarrhea, low heart rate, seizures, and even death.

Purified mistletoe, which is made for injection, is a safer form of mistletoe. Side effects are inflammation at the injection site, headache, fever, and chills, though these are not very common. Side effects of purified mistletoe tend to be minor and not serious enough to cause concern. In rare cases, a person could be allergic and have a reaction that can cause trouble breathing, rash, redness, and low blood pressure.

You should talk to your provider about any questions you have about mistletoe.