Prescriptions for powerful painkillers such as morphine have soared in the last 20 years and researchers say problems of addiction and death through overdose are rising in their wake.
In the US, deaths involving opioid analgesics rose more than threefold between 1999 and 2007, from 4,041 to 14,459. They are now more common than deaths from HIV and liver disease caused by excessive drinking.
There are no equivalent figures for the UK, but the number of prescriptions for the strong painkillers has risen fivefold to more than 15 million a year. Most deaths are caused by unintentional overdose – the gap between therapeutic and fatal dose can be narrow – and the victims are often young.
The actor Heath Ledger, pictured, died in 2008 of an overdose aged just 28. He was taking a cocktail of prescription drugs of which the key constituent was the powerful opioid painkiller oxycodone. More than 600,000 prescriptions for oxycodone were filled in the UK in that year, up from 600 in 1999..
Writing in the British Medical Journal, researchers from the University of Toronto say addiction to opioids is a problem in all countries, including the UK. They call for tighter restrictions on the marketing of powerful painkillers, and better education for doctors to prevent "the spread of the crisis to other countries".
Dependence on painkillers in the UK remains a hidden problem as there is "absolutely no data", according to Cathy Stannard, consultant in pain medicine at North Bristol NHS Trust and author of Opioids in Chronic Pain. "What we do know is that patients on very high doses find it difficult to get off. A lot have depression or unpleasant thoughts and feelings and the painkillers get rid of that. That is problem use but it is not addiction."
"My plea is that doctors should act cautiously. If the dose rises above the recommended level, patients should be referred to a specialist."