A comprehensive systematic review has been published in the Cochrane Library of the benefits and harms of methylphenidate (Ritalin) for children and adolescents with attention deficit hyperactivity disorder (ADHD) (see enhanced article). All 185 trials included were assessed to be at high risk of bias. It was possible for people in the trials to know which treatment the children were taking, the reporting of the results was not complete in many trials and for some outcomes the results varied across trials. The authors concluded that the low quality of the underpinning evidence meant they could not be certain of the magnitude of any effects on teacher-reported ADHD symptoms and general behaviour and parent-reported quality of life of the children. The most common adverse events were sleep problems and decreased appetite. To quote from the conclusion, "At the moment, the quality of the available evidence means that we cannot say for sure whether taking methylphenidate will improve the lives of children and adolescents with ADHD".