CRD summary: This review assessed whether treatment with isotretinoin increases the risk of depression or suicide in people with acne. The authors concluded that the evidence does not show an increased risk. The evidence was examined thoroughly and supported the authors' conclusions. Nevertheless, there was uncertainty about aspects of the review process and not all relevant studies might have been included.

CRD commentary: The review addressed a clear question. A reasonable number of sources were searched for published studies, and the search strategies reported would allow an independent assessment of their performance. The authors did not mention language restrictions nor did they consider publication bias, which raises some doubt whether all relevant studies were included. The methods of study selection and data extraction did not give sufficient reassurance against reviewer bias and error. The lack of precision in the inclusion criteria concerning study design warranted a more rigorous selection process. Some limitations of the included studies were mentioned in the narrative, although study quality did not appear to have been assessed systematically. There was a lot of detail on the characteristics of the individual studies, with the exception of the participants. The narrative synthesis was appropriate and appeared thorough. Based on the studies reviewed, the authors' conclusion is justified.