Just 11% of those in drug treatment services for OTC drug addiction reported that their problems solely lay with prescription or OTC drugs, researchers found. The DoH commissioned the research from the National Treatment Agency for Substance Misuse.

The researchers found that in 2009/10 there were 32,510 individuals in treatment for a problem relating to OTC or prescription drug use. But only 3,735 of these reported such problems in the absence of problems with illegal drugs.

The study found that the number of people coming into treatment for problems with benzodiazepines, without concurrent illegal drug problems, has fallen over the past five years.

RCGP chairwoman Dr Clare Gerada said GPs were 'all too aware' of the damage done by addiction to prescription and non-prescription drugs.

'We are pleased with how well GPs have responded to the advice issued by the RCGP over the years,' she said.

'The RCGP has worked for more than two decades to improve GPs' knowledge and skills in the management of substance misuse and much of this work as been led by our own RCGP substance misuse unit.'

She added: 'GPs are aware of the importance of not creating dependence on prescription drugs, and make sure they prescribe responsibly and according to good practice guidelines.'

The researchers said they had been unable to establish a definite prevalence of addiction or dependency to prescription and OTC drugs. They said there were a range of problems with auditing addiction to prescription and non-prescription drugs.

In particular, there is a lack of appropriate software in GP practices to audit effectively and such audits take a long time to conduct, they said.

The report also uncovered concerns that the transition to GP commissioning would disrupt local treatment services.