Homeopathy: what does the "best" evidence tell us?

OBJECTIVE To evaluate the evidence for and against the effectiveness of homeopathy. DATA SOURCES The Cochrane Database of Systematic Reviews (generally considered to be the most reliable source of evidence) was searched in January 2010. STUDY SELECTION Cochrane reviews with the term "homeopathy" in the title, abstract or keywords were considered. Protocols of reviews were excluded. Six articles met the inclusion criteria. DATA EXTRACTION Each of the six reviews was examined for specific subject matter; number of clinical trials reviewed; total number of patients involved; and authors' conclusions. The reviews covered the following conditions: cancer, attention-deficit hyperactivity disorder, asthma, dementia, influenza and induction of labour. DATA SYNTHESIS The findings of the reviews were discussed narratively (the reviews' clinical and statistical heterogeneity precluded meta-analysis). CONCLUSIONS The findings of currently available Cochrane reviews of studies of homeopathy do not show that homeopathic medicines have effects beyond placebo.