Mistletoe Therapy in Cancer Care

What Is Mistletoe Therapy?

Mistletoe therapy uses standardised extracts of Viscum album (European mistletoe), administered as subcutaneous injections. In integrative oncology, it is prescribed alongside — not instead of — conventional cancer treatment to improve quality of life, reduce fatigue, and support immune function.

The active constituents of mistletoe include lectins (ML-I, ML-II, ML-III) and viscotoxins, which have demonstrated immunomodulatory properties in laboratory and clinical studies. Clinically, the most robust evidence is for improvements in quality of life, cancer-related fatigue, and tolerance of chemotherapy — not for direct anti-tumour effects.

Mistletoe preparations are available under several brand names including Iscador, Helixor, and Abnoba Viscum. The host tree from which the mistletoe is harvested (oak, apple, pine, fir) affects the lectin composition and is selected according to the cancer type and patient constitution. Dr Kloppenburg selects the appropriate preparation and dose individually for each patient.

Mistletoe therapy has been used in European oncology for over a century and is the most commonly used complementary therapy in cancer patients in Germany, Switzerland, and Austria. In the UK, it is available through integrative medicine specialists including at the Royal London Hospital for Integrated Medicine (RLHIM), where Dr Kloppenburg holds her NHS appointment.

Mechanism of Action

Mistletoe lectins stimulate natural killer (NK) cell activity and increase the production of interleukin-1 (IL-1), interleukin-6 (IL-6), and tumour necrosis factor-alpha (TNF-α). This immunostimulatory effect is thought to underlie the improvements in fatigue and wellbeing observed in clinical trials. Viscotoxins have demonstrated direct cytotoxic effects on tumour cells in vitro, though the clinical significance at therapeutic doses remains under investigation.

The subcutaneous route of administration produces a local inflammatory response at the injection site — a small red wheal — which is considered a marker of immune activation and a positive indicator of therapeutic response. Dose titration is guided by this local reaction.

Safety and Drug Interactions

Mistletoe is generally well tolerated. The most common adverse effects are local injection-site reactions (redness, warmth, mild swelling) and, at higher doses, transient flu-like symptoms including mild fever. These are typically self-limiting and may indicate immune activation.

Contraindications include active autoimmune conditions, hypersensitivity to mistletoe, and certain immunotherapy protocols where immune stimulation may be contraindicated. Dr Kloppenburg reviews your complete oncology protocol before prescribing. For patients on immunotherapy (checkpoint inhibitors), mistletoe is not prescribed without direct communication with the treating oncologist.