Side Effects and Complications
Opioid side effects are well known and include respiratory depression, nausea, sedation, euphoria or dysphoria, constipation and itching. With chronic use, most side effects subside, since tolerance seems greater to side effects than to analgesic effects. Constipation is an exception, and there appears to be no tolerance to the direct slowing effects of opioids on the bowel, so that constipation remains a high risk and usually requires treatment. Although common side effects (except constipation), usually subside during chronic treatment, they can sometimes interfere to the extent that patients abandon the therapy. Respiratory depression is rarely seen during chronic opioid therapy, but since this is a potentially lethal side effect, one should remain vigilant. The situation in which it most likely arises during chronic opioid pain treatment is when the dose is rapidly escalated, dosing errors occur, or when drugs with unpredictable pharmacokinetics such as methadone are used. (Methadone's complexities are described under Structured Opioid Therapy). Other complications of opioid use are more insidious, tend to be associated with long-term rather than short-term use, and are complex and poorly understood. These include hormonal and immune effects, and addiction.
South Med J. 2006;99(11):1245-1255. © 2006 Lippincott Williams & Wilkins
Cite this: Opioids for Chronic Nonterminal Pain - Medscape - Nov 01, 2006.