Herbal medicines for asthma: a systematic review

CRD COMMENTARY: This was a well-conducted review. The research question was clear and appropriately applied via the study selection criteria. The search was good with no language restrictions, although it is possible that searches of AMED and of specialist Chinese, Indian and Japanese databases may have yielded more studies. An appropriate method was used to assess validity and the results of the assessment were presented and discussed. Adequate details of the included studies were presented and, given the clinical heterogeneity between the studies, a narrative synthesis seems to have been appropriate. Limitations of the studies included in the review are the lack of between-group comparisons and the lack of data on adverse effects, which the review authors also comment on. The authors' conclusions follow from the results presented.