Long before the discovery of endogenous opioid systems, opium was used to produce insensibility and relieve pain. Societies began regulating opiates when the availability and use of opiate drugs reached a level that made opiate addiction a problem to society. In the United Kingdom and the United States this was at the beginning of the 20th century, with the Drug Enforcement Act in the UK (1920) and the Harrison Act in the US (1918). Before regulations, opiates were widely available in chemist shops, doctors' surgeries, and opium dens, and the choice of use was entirely up to the individual, with the risk of addiction being understood. None the less, a stigma was attached to the use of opiates, even therapeutically, but nothing like that seen after regulations made the use of opiates, other than by prescription, a criminal offence. Once these regulations were introduced, a hugely profitable illicit trade in opiates began. This, along with the increasing problems in society attributed to abuse of opiates and other drugs, inevitably compounded the stigma attached to these drugs and affected the use of opiates for relieving pain.

Pain advocacy—lobbying for (opiate) treatment of pain—is a powerful movement in the US, more so than in the UK. …