GPs should start collecting anonymous data on patients they suspect or know to be hooked on prescription drugs, a group of MPs has found.
There is a lack of data on misuse and supply of prescription drugs for non-medicinal purposes and the spread and scale of the problem needs to be established, the Home Affairs Select Committee said.
Further efforts to tackle "doctor-shopping", when addicts visiting multiple practices to request specific drugs, are also needed, the MPs said.
The committee heard estimates that as many as 1.5 million people are addicted to prescription drugs in the UK.
Committee chair Keith Vaz MP said: "There are currently 1.5 million people addicted to prescription drugs in the UK. The abuse of these types of substances is taking place in the shadows and its extent is still unquantified.
"Local GPs need to report their suspicions and collate information to illuminate this problem."
Lack of action would lead to "catastrophic consequences", Mr Vaz said.
In its report, the committee said it recognises the " difficulties" in gathering information on prescription drug addicts due to the "sensitivity of medical data".
But immediate steps still need to be taken to introduce a system whereby anonymous data can be collated to "fully understand where the problem lies", the cross-party group said.
" We recommend that medical practices start an anonymous data collection of those patients who have been proven to be, or a medical professional has reasonable suspicion of being, addicted to prescription drugs and how they are being supplied," the report said.
The MPs recommended that the Royal College of General Practitioners produce guidance for GPs treating addiction to prescription drugs, stating that all cases ought to be recorded on the National Drug Treatment Monitoring System.
Un der the previous health service structure, primary care trusts would alert all practices in the local area if there was an individual visiting multiple practices to request specific drugs, the MPs said.
The highlighting of so-called doctor shopping now needs to be " formalised" in order for it to continue with the structural changes in healthcare in UK, the MPs said.
NHS England should issue guidance to local clinical commissioning groups (CCGs), so they take on the gathering of data on patients visiting multiple practices to request specific drugs, the report also recommended.
The committee cited work by the All Party Parliamentary Group for Involuntary Tranquilliser Addiction which estimates that 1.5 million people are addicted to these type of drugs, far higher than those who are in treatment for addiction to illegal drugs.
Dr Chaand Nagpaul, chair of the BMA's GP committee, said: "GPs already play a key role in treating patients in the community suffering from the impact of drug addiction. It is a devastating medical condition that ruins lives, families and communities and it is right that we continuously look at how we can improve drug addiction treatment.
"However, the identification of individuals addicted to prescription drugs is not straightforward and whilst we should do all we can to support their withdrawal from such drugs, we also need to ensure that patients are confident that their sensitive personal data will remain secure.
"Any data collection exercise is properly considered, piloted and tested before it is implemented."