Synopsis
Prevent opioid-induced constipation from the first dose, diagnose rectal loading and obstructive complications, select stimulant, osmotic or rectal treatment by stool and transit pattern, and use peripheral opioid antagonists only after conventional care and safety checks.
- Ask every patient starting a strong opioid about baseline bowel pattern and prescribe constipation prevention immediately unless diarrhoea or obstruction makes it unsafe.
- First-line opioid regimen usually combines a stimulant such as senna with an osmotic softener such as macrogol, individualised to intake and stool consistency.
- Do not rely on docusate alone for established opioid dysmotility and avoid bulk-forming fibre when intake is poor, transit is slow or obstruction is possible.
- Assessment covers last satisfactory stool, form, straining, incomplete emptying, flatus, pain, vomiting, overflow, medicines, intake, mobility and toilet access.
- Examine abdomen and perform rectal examination with consent when impaction, outlet disease or distal obstruction will change care; first assess bleeding and infection risk.
- Hard rectal stool requires a rectal or disimpaction plan; adding only more proximal oral laxative may worsen pain and overflow.
- Suspected complete obstruction, perforation or severe colic means stop stimulant, bulk and rectal treatment until urgent assessment.
- Consider naloxegol or another peripherally acting mu-opioid antagonist only for opioid-induced constipation inadequately controlled by conventional laxatives and after obstruction and interaction review.
- The gold-standard bowel plan states prophylaxis, stool target, escalation steps, rectal branch, obstruction red flags and review after every opioid or route change.
Key red flags
Obstipation, colic, vomiting and marked distension suggests obstruction and makes bulk-forming, stimulant and high-volume oral regimens unsafe until assessed.
Peritonism, fever, shock or sudden severe pain suggests perforation, ischaemia or stercoral complication and needs emergency review.
Overflow diarrhoea does not exclude impaction; liquid stool can pass around a hard rectal mass.
New urinary retention, agitation, nausea, reflux or reduced oral absorption can be caused by faecal loading even without volunteered constipation.
Rectal examination or treatment may cause bleeding or infection in severe thrombocytopenia, neutropenia, anal disease or recent pelvic treatment and needs individual risk review.
Peripheral opioid antagonists are contraindicated or high risk in known or suspected mechanical obstruction because perforation can occur.
New saddle symptoms, leg weakness or sphincter dysfunction requires emergency spinal or cauda-equina assessment rather than laxative escalation.
Investigation priorities
Establish usual pattern, last satisfactory stool, Bristol type, straining, overflow, flatus, pain, vomiting, intake, mobility and constipating exposure.
Management branches
A strong opioid is initiated or increased and no obstruction or diarrhoea contraindicates prophylaxis.
- Record baseline bowel pattern, renal and cardiac status, intake and existing constipating medicines and agree a comfortable stool target.
- Start formulary senna plus macrogol or another stimulant-osmotic combination and give written dose, hydration, escalation and red-flag advice.
- Review within days and after every opioid change, titrating individual components to stool form and frequency and checking adherence and toilet access.