Last summer, I took the painkiller co-codamol for back pain. I started with the lowest dose of codeine (8mg), but then took the 30mg tablets for two months. Coming off it gave me the experience of "cold turkey"; I felt very strange and agitated, and sleep proved difficult. With advice from NHS addictive drug agencies, I managed to get off them. My question is: how common is such an experience and should I have been warned? There is no reference to addiction in the patient information leaflet.

Dr Fred Kavalier answers your health question:

Co-codamol is a combination of paracetamol and codeine. It comes in the two strengths of codeine you mention. The combination of paracetamol and codeine is more effective than either drug on its own. Most people don't realise that natural codeine is extracted from opium. (It can also be made synthetically from morphine.) It is a narcotic which, like heroin and morphine, can cause physical addiction. The higher dose of codeine, a Class B drug, is regulated by the Misuse of Drugs Act 1971.You should have been warned that addiction to codeine can be a problem, particularly if taken for prolonged periods in high doses. Some versions of the information leaflet mention addiction, but others do not. One leaflet I have seen says: "Taking co-codamol regularly for a long time can lead to addiction, which might cause you to feel restless and irritable when you stop taking the medicine. If you are concerned about this, discuss the problem with your doctor or pharmacist." But another version of the leaflet that was authorised by the Medicines and Healthcare products Regulatory Agency (MHRA) in February 2006 makes no mention of addiction. The MHRA should look into this.

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