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.