According to pain experts, most of this suffering is unnecessary and could be alleviated by the wider use of opioid analgesics. Reasonable fears over uncontrolled use of street narcotics have produced unreasonable attitudes about the drugs that are the most effective for controlling pain in patients who are chronically, seriously, or terminally ill. Education about the mechanisms of pain and addiction has been limited. Addiction refers to compulsive drug use, the loss of control over drug use, and continued use despite harm. Drug tolerance and dependence are relevant to the medical use of pain drugs.
Tolerance means that the body needs more of a particular medication to maintain an effect.
A cancer patient may need increasing doses of an opioid to relieve pain. Physical dependence, on the other hand, means that a person may experience symptoms of withdrawal if the drug is abruptly discontinued. Dependence is not unique to opioids. Opioids are among those medications that are best withdrawn gradually if they are to be replaced with another medication or discontinued. Recent research indicates that diversion can be controlled without impeding the medical use of opioids.