Side Effects, Tolerance and Addiction

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Side Effects
  • chills
  • nausea
  • constipation
  • vomiting

Other possible side effects include:

  • fever
  • sweating
  • abdominal pain
  • diarrhea

(SAMHSA 2004)


Individuals who repeatedly use opioids are likely to develop a tolerance for opioids. Tolerance is a neurological change in which opioid receptors become less sensitive (Taylor and Fleming 2001). As a result, the opioid user needs increasingly larger opioid doses in order to achieve the same effects (APA 2000). Tolerance is a normal consequence of being on chronic opioid therapy.


The development of tolerance causes the individual's neurological system to adapt to the presence of opioids. The neurological system then becomes unable to function "normally" when there is a decrease in opioid levels (Kosten and George 2002). Once an individual has developed a physical dependence, cessation of opioid administration will lead to the onset of physical withdrawal. It is normal to develop physiological dependence on chronic opioid therapy; it becomes an addictive disorder when it disrupts the individual's life as described below.

It is important to note that the problems of opioid use disorder (commonly thought of as "addiction") are different from physiological opioid dependence which is normal in chronic opioid therapy.

When the individual experiences the last 3 behavior changes under dependence, they are addicted rather than simply physiologicaly dependent. In the future DSM, this will be called addiction again to distinguish it from the normal physiological dependence that everyone experiences if on chronic opioid therapy.
View ReferencesHide References
American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 4th ed, Text Revision. Washington, DC. American Psychiatric Association. 2000.
Metabolic consequences of drug misuse. Br J Anaesth. 2000; 85(1): 136-142.
The neurobiology of opioid addiction: implications for treatment. NIDA Science and Practice Perspectives. 2002; 1(1): 13-20.
Unifying perspective of the mechanisms underlying the development of tolerance and physical dependence to opioids. J Pharmacol Exp Ther. 2001; 297(1): 11-18.