to glossary

Opioid dependence

Opioid dependence is a physiological dependence on opioids and similar substances that have sedative (calming) and pain-relieving effects. These substances, such as morphine, heroin, and other opioids, can cause severe dependence in people who use them.

Opioids affect the central nervous system and can cause physical dependence: the body adapts to the presence of the substance and begins to require it to function normally. A person may experience severe physical symptoms when attempting to stop using opioids; this is known as withdrawal syndrome.