Adverse effects of homeopathy: a systematic review of published case reports and case series – response by Posadzki and Ernst

AIM The aim of this systematic review was to critically evaluate the evidence regarding the adverse effects (AEs) of homeopathy. METHOD Five electronic databases were searched to identify all relevant case reports and case series. RESULTS In total, 38 primary reports met our inclusion criteria. Of those, 30 pertained to direct AEs of homeopathic remedies; and eight were related to AEs caused by the substitution of conventional medicine with homeopathy. The total number of patients who experienced AEs of homeopathy amounted to 1159. Overall, AEs ranged from mild-to-severe and included four fatalities. The most common AEs were allergic reactions and intoxications. Rhus toxidendron was the most frequently implicated homeopathic remedy. CONCLUSION Homeopathy has the potential to harm patients and consumers in both direct and indirect ways. Clinicians should be aware of its risks and advise their patients accordingly.