CRD Summary: The authors concluded that the randomised controlled trials (RCTs) have demonstrated the effectiveness of botulinum toxin in the management of sialorrhoea. Given that some relevant papers might have been missed, there were uncertainties in the review process and the results relied upon two RCTs, the conclusions are unlikely to be reliable.

[The included studies assessed BOTX-A (Allergan), BOTX-A (Dysport) or BOTX-B in the management of sialorrhoea (excessive drooling).]

CRD Commentary: The review addressed a clear question and inclusion criteria, in terms of sample size and publication type, were stipulated. The restriction of the literature search to English language papers might have resulted in the omission of some relevant data, as may have the restriction of the review to papers published in peer-reviewed journals for what is a relatively new treatment. The possibility of reviewer error and bias cannot be assessed as the methods used to select studies and extract the data were not described. In addition, it is not possible to comment on the reliability of the results as validity assessment was not undertaken. The quality of most of the included studies was poor, with considerable heterogeneity evident between studies. Given the weaknesses and uncertainties in the review process and the reliance upon two very small RCTs, the conclusions may not be reliable and so should be treated with caution.