RESEARCH STARTER

Mistletoe and cancer

Mistletoe, specifically the species Viscum album, has been explored for its potential use in cancer treatment, particularly in Europe and the United States. Known for its semi-parasitic growth on trees and historical use as a medicinal plant, mistletoe contains compounds such as viscotoxins and lectins that may exhibit anticancer properties. These substances are thought to work by inhibiting cancer cell protein synthesis and inducing programmed cell death, along with modulating the immune system, which could enhance the body's ability to combat cancer. Various cancers, including breast and pancreatic cancer, have been the focus of mistletoe research, with delivery methods typically involving injections of its extracts.

While clinical trials have shown promise, they often faced challenges such as small sample sizes or design flaws, raising questions about their validity. Recent studies, including one from Johns Hopkins Kimmel Cancer Center in 2023, are beginning to provide more robust evidence supporting mistletoe's potential benefits in improving quality of life for cancer patients. However, it is essential to note that mistletoe can be toxic if ingested, causing serious health issues, and may lead to side effects when used medicinally, though they are generally mild. As with any treatment, particularly in sensitive populations like pregnant women, caution and consultation with healthcare professionals are advised.

Full Article

  • ALSO KNOWN AS: Viscum album Lorantaceae, All Heal

DEFINITION: European and American varieties of mistletoe are semiparasitic, woody evergreen plants with white berries that grow on deciduous trees. Mistletoe has a long history of use in Europe and Asia as a medicinal cure-all, and the species Viscum album Lorantaceae in particular has been studied for the treatment of multiple types of cancer.

Cancers treated or prevented: Breast cancer, pancreatic cancer, and other cancers

Delivery routes: Intramuscular, subcutaneous, or intravenous (IV) injection of water-based or water-and-alcohol-based extracts

How this substance works: American and European mistletoe plants both contain toxins that provide pharmacologic effects on multiple organ systems. The Viscum album species is the primary one used medicinally and provides activity via four viscotoxins, three distinct lectins (ML1–3), and the specific lectin viscumin. These toxins are found in the main commercial products, Iscador and Helixor. The cytotoxic viscotoxins and lectins provide the plant’s potential direct anticancer activity by inhibiting protein synthesis in cancer cells and by inducing apoptosis (programmed cancer cell death), respectively.

Immunomodulation is another possible mechanism for treating cancer and controlling the side effects of chemotherapy. Mistletoe extract may increase white blood cell counts, protect deoxyribonucleic acid (DNA) in white blood cells exposed to damaging chemotherapy, and stimulate cellular secretions of cytokines, including tumor necrosis factor (TNF)-alpha, interleukin (IL)-1, and IL-6, from white blood cells. Increased natural killer cell activity has also been noted in breast cancer patients administered a single intravenous dose of standardized mistletoe preparation.

Varying effects have been observed with different extracts, doses, and types of cancer. Clinical trials have been conducted in Europe and the United States, but many studies had design flaws, such as small sample size or lack of randomization, which undermined the validity of their positive results. In the 2020s, however, that began to change. In 2023, researchers at Johns Hopkins Kimmel Cancer Center completed a clinical study of the effectiveness of Helixor M in patients with advanced and treatment-resistant cancers. Although initially intended only to test the safety of Helixor M, the study showed that its use provided disease control and increased quality of life for patients. Scientific evidence is moving to support the concept that enhanced immunity from mistletoe helps the body fight cancer cells.

Side effects: Mistletoe leaves and berries are poisonous to ingest and may cause symptoms such as nausea, vomiting, and diarrhea leading to dehydration; decreased heart rate and increased blood pressure, with possible vasoconstriction and cardiac arrest; delirium and hallucinations; and seizures.

Few side effects have been reported, however, with the medicinal use of the mistletoe extract. Common side effects observed with extract administration include injection site reactions, headache, fever and chills, and, rarely, anaphylactic shock or allergic reaction. Mistletoe is a uterine stimulant and should be avoided during pregnancy and lactation.


Bibliography

Horneber, M A et al. “Mistletoe Therapy in Oncology.” The Cochrane Database of Systematic Reviews, vol. 2, 2008, doi:10.1002/14651858.CD003297.pub2. Accessed 14 Oct. 2025.

“Mistletoe Extracts.” National Cancer Institute, 21 June 2023, www.cancer.gov/about-cancer/treatment/cam/patient/mistletoe-pdq. Accessed 14 Oct. 2025.

“Mistletoe Therapy in Clinical Studies.” Mistletoe-Therapy.org, www.mistletoe-therapy.org/scientific-information/clinical-evidence/clinical-studies. Accessed 14 Oct. 2025.

Nicoletti, Marcello. "The Anti-Inflammatory Activity of Viscum Album." Plants, vol. 12, no. 7, 2023, doi.org/10.3390/plants12071460. Accessed 14 Oct. 2025.

Sugarman, Joe. “Are Mistletoe Extract Injections the Next Big Thing in Cancer Therapy?” Johns Hopkins Magazine, 2014, hub.jhu.edu/magazine/2014/spring/mistletoe-therapy-cancer. Accessed 14 Oct. 2025.

“US Study of Intravenous Mistletoe Extract to Treat Advanced Cancer.” Johns Hopkins Medicine, 22 Feb. 2023, www.hopkinsmedicine.org/news/newsroom/news-releases/2023/02/us-study-of-intravenous-mistletoe-extract-to-treat-advanced-cancer. Accessed 14 Oct. 2025.

Full Article

  • ALSO KNOWN AS: Viscum album Lorantaceae, All Heal

DEFINITION: European and American varieties of mistletoe are semiparasitic, woody evergreen plants with white berries that grow on deciduous trees. Mistletoe has a long history of use in Europe and Asia as a medicinal cure-all, and the species Viscum album Lorantaceae in particular has been studied for the treatment of multiple types of cancer.

Cancers treated or prevented: Breast cancer, pancreatic cancer, and other cancers

Delivery routes: Intramuscular, subcutaneous, or intravenous (IV) injection of water-based or water-and-alcohol-based extracts

How this substance works: American and European mistletoe plants both contain toxins that provide pharmacologic effects on multiple organ systems. The Viscum album species is the primary one used medicinally and provides activity via four viscotoxins, three distinct lectins (ML1–3), and the specific lectin viscumin. These toxins are found in the main commercial products, Iscador and Helixor. The cytotoxic viscotoxins and lectins provide the plant’s potential direct anticancer activity by inhibiting protein synthesis in cancer cells and by inducing apoptosis (programmed cancer cell death), respectively.

Immunomodulation is another possible mechanism for treating cancer and controlling the side effects of chemotherapy. Mistletoe extract may increase white blood cell counts, protect deoxyribonucleic acid (DNA) in white blood cells exposed to damaging chemotherapy, and stimulate cellular secretions of cytokines, including tumor necrosis factor (TNF)-alpha, interleukin (IL)-1, and IL-6, from white blood cells. Increased natural killer cell activity has also been noted in breast cancer patients administered a single intravenous dose of standardized mistletoe preparation.

Varying effects have been observed with different extracts, doses, and types of cancer. Clinical trials have been conducted in Europe and the United States, but many studies had design flaws, such as small sample size or lack of randomization, which undermined the validity of their positive results. In the 2020s, however, that began to change. In 2023, researchers at Johns Hopkins Kimmel Cancer Center completed a clinical study of the effectiveness of Helixor M in patients with advanced and treatment-resistant cancers. Although initially intended only to test the safety of Helixor M, the study showed that its use provided disease control and increased quality of life for patients. Scientific evidence is moving to support the concept that enhanced immunity from mistletoe helps the body fight cancer cells.

Side effects: Mistletoe leaves and berries are poisonous to ingest and may cause symptoms such as nausea, vomiting, and diarrhea leading to dehydration; decreased heart rate and increased blood pressure, with possible vasoconstriction and cardiac arrest; delirium and hallucinations; and seizures.

Few side effects have been reported, however, with the medicinal use of the mistletoe extract. Common side effects observed with extract administration include injection site reactions, headache, fever and chills, and, rarely, anaphylactic shock or allergic reaction. Mistletoe is a uterine stimulant and should be avoided during pregnancy and lactation.


Bibliography

Horneber, M A et al. “Mistletoe Therapy in Oncology.” The Cochrane Database of Systematic Reviews, vol. 2, 2008, doi:10.1002/14651858.CD003297.pub2. Accessed 14 Oct. 2025.

“Mistletoe Extracts.” National Cancer Institute, 21 June 2023, www.cancer.gov/about-cancer/treatment/cam/patient/mistletoe-pdq. Accessed 14 Oct. 2025.

“Mistletoe Therapy in Clinical Studies.” Mistletoe-Therapy.org, www.mistletoe-therapy.org/scientific-information/clinical-evidence/clinical-studies. Accessed 14 Oct. 2025.

Nicoletti, Marcello. "The Anti-Inflammatory Activity of Viscum Album." Plants, vol. 12, no. 7, 2023, doi.org/10.3390/plants12071460. Accessed 14 Oct. 2025.

Sugarman, Joe. “Are Mistletoe Extract Injections the Next Big Thing in Cancer Therapy?” Johns Hopkins Magazine, 2014, hub.jhu.edu/magazine/2014/spring/mistletoe-therapy-cancer. Accessed 14 Oct. 2025.

“US Study of Intravenous Mistletoe Extract to Treat Advanced Cancer.” Johns Hopkins Medicine, 22 Feb. 2023, www.hopkinsmedicine.org/news/newsroom/news-releases/2023/02/us-study-of-intravenous-mistletoe-extract-to-treat-advanced-cancer. Accessed 14 Oct. 2025.

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