Laxative co-medication and changes in defecation patterns during opioid use.

One in four opioid starters did not dispose of laxative co-medication, mainly because they were not considered necessary by either the prescriber or the patient. The prevalence of constipation doubled during opioid use. A watchful waiting strategy for the use of laxative co-medication might include a monitoring of defecation patterns with validated questionnaires.