Abstract
(1) Background: Classical (=individualized) homeopathic therapy is based on the individual and not on the indication. (2) Methods: The prerequisite for conducting methodologically high-quality studies on indvidualized homeopathy is that the principles of homeopathy are considered, since the selection of the simile (the individually appropriate homeopathic medicinal product) is decisive for the effectiveness of the homeopathic treatment, because only an application lege artis can be effective for the respective patient. Apart from this, criteria for evidence-based medicine must be considered for design, conduction, documentation, and rating of studies in homeopathy. (3) Results: When criteria for evidence-based medicine for design, conduction, documentation, and rating of studies in homeopathy are considered, effects on all quality levels according to Cochrane criteria are recognizable, especially for individualized homeopathy, even in the methodologically high-quality studies. (4) Conclusions: Based on the following three facts, the discussion of the evidence in human and veterinary homeopathy lays the foundations for a comprehensive presentation of the evidence on homeopathy: (a) homeopathic medicinal products without indication are 100% identical with regard to production, quality, safety, and principles of application, regardless of whether they are used in animals or humans; (b) if the simile principle (Similia similibus curentur, or 'Let like be cured by like') is adhered to that classical (=individualized) homeopathic therapy is based on the individual and not on the indication; and (c) if the proof of effectiveness of individualized homeopathy in one or more indications is available, the logical consequence seems to be that it can be concluded that it is effective in other indications. In view of One Health and of the demands of the European Green Deal (Farm2Fork Strategy) and the EU Organic Regulation 2018/848, the application of homeopathy in the sense of integrative veterinary medicine and the integration of complementary medicine including homeopathy at universities seems a necessary consequence and requirement in the interests of the patient, which is already expressed in the American consensus guidelines for an integrative veterinary medicine curriculum and is legally anchored in Switzerland by the Medical Professions Act for university teaching and research.