Burden of opioid-associated gastrointestinal side effects from clinical and economic perspectives: a systematic literature review.

Opioid analgesia is the mainstay of treatment for moderate to severe acute and chronic pain and is highly effective in relieving pain but can be limited by side effects, the most common of which affect the gastrointestinal (GI) and central nervous systems. A growing body of evidence demonstrates that opioid-associated GI side effects constitute an important health problem with significant humanistic and economic consequences that warrant consideration by healthcare professionals and administrators in optimizing patients' pain management. This article documents the frequency of opioid-associated GI side effects and describes its clinical and economic burdens based on a systematic review of the medical literature between 1966 and 2008.