Quick Summary

Mistletoe (Viscum album) is widely used in integrative oncology as a complementary therapy primarily in cancer care. It may help improve quality of life and assist in managing treatment side effects. Mistletoe has immunomodulatory properties and has been studied for effects on cancer-related fatigue, overall survival in cancers such as pancreatic, breast, and non-small cell lung cancer, and symptom management. Evidence is mixed: some studies show moderate quality of life benefits and possible survival improvement in certain contexts, while high-quality trials and meta-analyses present heterogeneous findings. Safety concerns primarily include local skin reactions and rare systemic reactions, with caution advised for intravenous use due to transient liver enzyme elevations. Drug interactions and contraindications are under-studied, and further well-designed randomized controlled trials are needed for conclusive findings.

What is it

Mistletoe is a semi-parasitic plant, scientifically known as Viscum album, that grows on various trees. Extracts from mistletoe have been traditionally used in various medical systems and are now studied primarily in integrative oncology settings as an adjunctive therapy.

Traditional Uses

Mistletoe extracts have a long history of complementary use in cancer care, particularly in Central Europe. Traditionally, they have been used to support immune function, improve symptoms related to cancer and cancer treatments, and enhance overall well-being during oncological therapies.

Active Compounds

Mistletoe contains several bioactive compounds thought to contribute to its effects, including mistletoe lectins, viscotoxins, polysaccharides, and flavonoids. These compounds are believed to have immunomodulatory and cytotoxic properties based on preclinical studies.

Potential Benefits with Evidence Levels

  • Improvement in health-related quality of life (HRQoL) in cancer patients: Moderate quality evidence from multiple randomized controlled trials and meta-analyses indicates a moderate improvement in quality of life, particularly in breast and pancreatic cancer patients. Some trials report benefits in fatigue, pain, and emotional functioning.
    References: [35239008, 37888846, 37754510, 35325897, 41145311]
  • Potential survival benefit in some cancer populations when added to standard therapy: Evidence is mixed. Several meta-analyses suggest possible survival benefits, especially in pancreatic and non-small cell lung cancer patients treated with mistletoe extracts alongside standard care. However, methodological heterogeneity and risk of bias limit firm conclusions. Observational data indicate potential survival improvement when mistletoe is combined with immune checkpoint inhibitors in NSCLC.
    References: [31927541, 36324298, 38672690, 39770555, 41145311]
  • Reduction in cancer-related fatigue: Systematic reviews and meta-analyses of randomized controlled trials suggest a moderate benefit in reducing cancer-related fatigue, although evidence quality ranges from low to moderate and placebo-controlled studies are limited.
    References: [35239008, 38754041]
  • Immunomodulatory effects supportive in cancer therapy: Preclinical and some clinical observational studies suggest mistletoe compounds stimulate immune responses relevant to cancer, including effects on natural killer (NK) cells and cytokine modulation. Human trials provide preliminary support for these immunological effects.
    References: [31118962, 40864825, 29237435]
  • Potential supportive role in symptom management during cancer treatment: Clinical guidelines and integrative oncology practices recommend mistletoe among interventions to improve treatment tolerability and symptom control. Evidence is limited by study quality and heterogeneity.
    References: [41278285, 32690087, 36160875]

Side Effects

Mistletoe extracts are generally well tolerated. Common side effects include:

  • Local injection site reactions such as redness, swelling, and itching
  • Mild systemic reactions including fatigue, nausea, and chills
  • Transient increases in liver enzymes following high-dose intravenous administration
  • Rare hypersensitivity or skin reactions reported in pharmacovigilance databases
  • Potential immune-related adverse events when combined with immune therapies have not been shown to increase

Drug Interactions

Data on herb-drug interactions with mistletoe are limited. Current observational studies indicate no increased adverse events when combined with immune checkpoint inhibitors, but detailed interaction profiles and risks remain insufficiently studied. Caution and vigilant monitoring are advised in multimodal oncology care settings.

Who Should Avoid It

Use of mistletoe extracts should be cautious or avoided in:

  • Individuals with known hypersensitivity to mistletoe or its extracts
  • Patients with unstable immune function or autoimmune conditions
  • Pregnant or breastfeeding women due to lack of safety data
  • Patients considering high-dose intravenous administration, as it is currently discouraged due to potential hepatotoxic risk

Evidence Limitations

  • Many clinical studies exhibit high heterogeneity and methodological limitations, with risk of bias ranging from moderate to high
  • Lack of adequate placebo-controlled, double-blind randomized trials with sufficient sample sizes
  • Variability in commercial mistletoe preparations, extraction methods, host trees, and dosing regimens complicates comparisons
  • Limited long-term safety data, especially regarding intravenous administration
  • Real-world observational data may be confounded and cannot establish causality
  • Insufficient detailed herb-drug interaction studies available
  • Few studies address use in pregnant or breastfeeding populations

References

Last Reviewed

June 2024

Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice. Always consult a healthcare professional before starting any new treatment or therapy, especially if you have existing health conditions or are taking medications.