Although Ritalin (methylphenidate) has been the drug of choice for around 20 years to treat ADHD (attention-deficit, hyperactive disorder) in children, it`s never been proven to work in any major independent study.

All of the 185 trials, which involved 12,245 children, are flawe usually because the drug`s manufacturer was the sponsor were too small, say researchers at the Cochrane Collaboration, an independent review group.

We cannot say for sure whether taking methylphenidate will improve the lives of children and adolescents with ADHD, the researchers conclude. However, the drug does cause a wide range of adverse reactions, such as insomnia and sleeping problems, and a loss of appetite.

The Cochrane researchers said the quality of the trials was very low; most of the participants knew whether they were being given Ritalin or a placebo, or sugar pill, the reporting of the results was often incomplete, and the results varied across the trials they reviewed.

(Source: Cochrane Collaboration, The Cochrane Library, 2015; issue 11)