The number of prescriptions for drugs such as Ritalin to treat attention deficit hyperactivity disorder has risen sharply, official figures show.
There has been a 50% rise in the use of drugs for attention deficit hyperactivity disorder in six years.
Prescriptions for methylphenidate drugs, including Ritalin, rose from 420,000 in 2007 to 657,000 last year, the Care Quality Commission said.
The watchdog warned health workers to "carefully monitor" their use as they have the potential to be "abused".
The drugs are one of a number linked to the "smart-drug" craze, where students take medication to help them focus.
Methylphenidate is known as a psychostimulant.
While it is not completely clear how it works, it is thought to stimulate a part of the brain that changes mental and behavioural reactions.
The CQC report - its annual review of controlled drugs - said the number of prescriptions for such medications rose by 11% between 2011 and 2012.