Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.
2 min synopsisUK scopeSources checked 27 Aug 2026Clinical review pending
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Constipation with obstruction or perforation
Severe colic, progressive distension, vomiting, obstipation, peritonism, fever, shock or sudden pain may represent bowel obstruction, stercoral perforation, ischaemia or sepsis.
Action: Stop oral and rectal laxatives that could worsen obstruction, use ABCDE care, protect the airway and obtain urgent abdominal imaging and surgical or oncology review within goals. Provide non-oral analgesia and antiemetic treatment while correcting fluid and electrolyte compromise proportionately.
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.
Key red flags
Obstipation, colic, vomiting and marked distension suggests obstruction and makes bulk-forming, stimulant and high-volume oral regimens unsafe until assessed.
Mechanical obstruction
Colic, progressive distension, vomiting and obstipation with malignant or surgical history requires urgent imaging and treatment change.
Investigation priorities
01
First-line bowel and medicine historyFirst stepFirst line
Establish usual pattern, last satisfactory stool, Bristol type, straining, overflow, flatus, pain, vomiting, intake, mobility and constipating exposure.
Management branches
Opioid prophylaxisStart stimulant and softener together
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.
Key medicines
Senna stimulant prophylaxisStart 15 mg orally at night in many adults beginning strong opioid treatment, increasing to 30 mg at night or a local divided regimen according to stool response and the BNF.
Macrogol osmotic laxativeUse one compound macrogol sachet orally daily initially and titrate commonly to one to three sachets daily; use the product's separate impaction regimen only after obstruction exclusion and with adequate fluid and supervision.
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.