[Recommendations of the German Society for Rheumatology committee for complementary treatment and nutrition on phytotherapy : Supplement on the use of selected phytotherapeutic agents and herbal preparations in rheumatology: extension to include 13 medicinal plants].

INTRODUCTION: Medicinal plants and their preparations are of great interest to many patients with rheumatic diseases. In 2023 the German Society for Rheumatology and Clinical Immunology (DGRh) Committee for Complementary Medicine and Nutrition (KHE) began reviewing the scientific literature on selected phytotherapeutic agents and herbal preparations and examining their potential applications in rheumatology. Following the publication of the initial results in 2025, the evaluation of 13 additional phytotherapeutic agents took place later that same year.

METHODS: In an online meeting of the KHE Committee on 7 January 2025, a further list of phytotherapeutic agents frequently used in rheumatology (mostly as self-medication) was compiled. Committee members then conducted literature searches on these herbal preparations and summarized the results according to a predefined matrix. Research was conducted on comfrey, arnica, turmeric, ginger, cat's claw (Uncaria tomentosa), garlic, cabbage leaves, milk thistle, Pycnogenol (extract from the bark of maritime pine), horsetail, devil's claw (Harpagophytum), frankincense (Boswellia) and Wilford's tripter fruit (Tripterygium wilfordii). The results were reviewed using a circulation procedure, a consensus was agreed upon in an online meeting of the KHE committee and finally confirmed by the German Society for Rheumatology and Clinical Immunology (DGRh).

RESULTS: For all plant substances investigated, there are reports of anti-inflammatory or immunological effects in vitro and/or in animal models; however, the evidence for a clinically relevant benefit is very limited. None of the investigated preparations can be recommended for use in inflammatory joint diseases. If arnica, comfrey, turmeric, ginger, garlic, cabbage leaves, Pycnogenol, devil's claw or frankincense are taken at the patient's own initiative for degenerative joint diseases, rheumatologists do not need to advise against them, provided a sensible treatment plan is otherwise being followed. Ginger, garlic and turmeric in their natural form can be recommended as foods within the framework of a health-conscious diet.

CONCLUSION: The scientific analysis of a second series of herbal preparations has also shown that the confirmed value of phytotherapy for the field is limited; however, for the rheumatological practice a differentiated consideration is needed for the herbal preparations presented here.