Opioids: Why 'dangerous' drugs are still being used to treat pain
The widespread use of opioids to treat pain frequently prompts concerns about addiction and even deaths. So, why are these sometimes dangerous drugs still being given to patients?
Much stronger than many of the other options, opioids are among the world's most commonly prescribed painkillers. These drugs - including morphine, tramadol and fentanyl - are used to treat pain caused by everything from heart attacks to cancer.
Why not just use other painkillers to avoid the risk of harm?
Despite their benefits, the problems associated with these medicines are clear. For decades, scientists have tried to develop opioids that work without causing the problems of addiction and misuse.
Some have added extra ingredients deliberately to cause a distressing reaction. For example, added to opioid tablets, the antidote naloxone largely has no side-effects if the medication is taken orally, but causes severe "cold turkey" withdrawal symptoms if the tablet is crushed and injected by a dependent user.