The guidelines state that methylphenidate is safe to use in children over the age of six, but that healthcare professionals should rigorously monitor patients for cardiovascular and psychiatric problems before and during treatment.

This monitoring should include assessment of height and weight, as well as BP, pulse and symptoms suggestive of heart failure, which should prompt specialist cardiac evaluation. Patients should also be watched for any changes in appetite and for onset or worsening of psychiatric symptoms, the MHRA has said.

Treatment should be interrupted annually to determine whether continuation is necessary, the guidelines say.

The new advice follows a review of the drug's safety by the European Medicines Agency last year.

The MHRA has also announced that patient information leaflets for methylphenidate products are being updated. The new leaflets will include a tear-off section for children and adolescents taking the medication, which has been written in an engaging style designed to appeal to young people with ADHD.