Cochrane encourages submission of comments via the Cochrane Library, but comments can be submitted directly to review authors or CRGs, or published in other journals, blogs, social media or other fora.

If comments are received via one of these fora, the contributors should be encouraged to submit their comments via the Cochrane Library. This ensures that they are given the opportunity to declare any potential conflicts of interest and enables them to agree to the terms and conditions relating to publication of comments. If the comment contributor declines to submit their comment via the Cochrane Library, the comment can still be processed in the usual manner, but permission for publication should be sought from the contributor, making them aware of the terms and conditions of publication. The contributor should also be asked to disclose any potential conflicts of interest.

Comments posted on other journals, blogs, social media or other fora should be judged on merit and may prompt an amendment or update the review. In these cases the comments should be acknowledged or cited.

The Altmetric system can provide a useful source of comments on reviews. Comments posted on PubPeer (pubpeer.com) are captured by Altmetric and recorded as ' Peer review' items. You can view the Altmetric data for any Cochrane Review by clicking on the Altmetric logo or score associated with the Review on the Cochrane Library.