What is the first‑line management of constipation in an adult inpatient who can take oral medication, including considerations for opioid‑induced constipation?

First-Line Management of Constipation in Hospitalized Adults

Start a stimulant laxative (senna or bisacodyl) immediately for all hospitalized patients with constipation, and if the patient is on opioids, this should have been initiated prophylactically at the time opioids were started. 1, 2

Initial Assessment Before Treatment

Before initiating or escalating laxative therapy, you must:

• Rule out bowel obstruction through clinical examination and imaging if indicated 3, 1, 2
• Check for fecal impaction via digital rectal examination 2
• Assess for hypercalcemia, hypokalemia, hypothyroidism, and diabetes as reversible causes 2
• Review all medications for constipating agents (anticholinergics, calcium channel blockers, iron supplements) 3, 2

First-Line Pharmacologic Treatment

For General Constipation (Non-Opioid Related)

Stimulant laxatives are the primary first-line agents:

• Senna 2 tablets (17.2 mg) every morning, titrate up to twice daily if needed 1, 2
• Bisacodyl 5-15 mg daily, can increase to 10-15 mg two to three times daily 2

Osmotic laxatives as alternative or addition:

• Polyethylene glycol (PEG) 17 grams in 8 oz water twice daily is highly effective and well-tolerated 3, 2
• Lactulose or magnesium-based products (magnesium citrate, magnesium hydroxide) are alternatives 3

For Opioid-Induced Constipation Specifically

The approach is identical but must be prophylactic:

• Start stimulant laxatives (senna or bisacodyl) simultaneously with the first opioid dose 1, 2
• The American Gastroenterological Association strongly recommends laxatives as first-line agents for opioid-induced constipation with moderate-quality evidence 3
• Studies show PEG and sodium picosulfate are more efficacious than lactulose for opioid-induced constipation 3

Treatment Goal

Achieve one non-forced bowel movement every 1-2 days 3, 1, 2

What NOT to Use First-Line

Avoid these common mistakes:

• Do NOT use docusate (stool softeners) alone – it has not shown benefit and is not recommended 3, 1, 2
• Do NOT use supplemental fiber (psyllium) – it is ineffective and may worsen constipation in hospitalized patients 3, 2
• Do NOT use bulk-forming laxatives as first-line therapy 1

Escalation for Persistent Constipation

If constipation persists after 24-48 hours on first-line therapy:

• Re-assess to rule out obstruction or impaction before escalating 3, 1, 2
• Increase bisacodyl to 10-15 mg two to three times daily 2
• Add an osmotic laxative (PEG, lactulose, or magnesium-based products) if not already using one 3, 2
• Consider rectal interventions (bisacodyl suppository 10 mg or glycerin suppository) but avoid in neutropenic or thrombocytopenic patients 3, 2

Non-Pharmacologic Measures

While important, these are adjunctive only and insufficient alone:

• Maintain adequate fluid intake 3, 1
• Encourage physical activity if feasible 1
• Adequate dietary fiber when appropriate 3

Laxative-Refractory Cases (Third-Line)

For patients failing adequate trials of stimulant and osmotic laxatives:

• Naldemedine 0.2 mg orally once daily has the strongest recommendation with high-quality evidence for opioid-induced constipation 3, 2
• Naloxegol 12.5-25 mg orally once daily is strongly recommended with moderate-quality evidence 3, 2
• Methylnaltrexone 0.15 mg/kg subcutaneously every other day is conditionally recommended with lower-quality evidence 2
• Use the Bowel Function Index (score ≥30 indicates clinically significant constipation) to objectively assess who needs escalation to peripherally acting μ-opioid receptor antagonists 3

Critical Pitfalls to Avoid

• Never delay prophylactic laxatives when opioids are started – up to 80% of patients develop constipation and tolerance never develops 2
• Never escalate stimulant laxatives without first ruling out obstruction 3, 1, 2
• Never rely on stool softeners alone – they are ineffective 1, 2
• Never use enemas containing sodium phosphate more than once daily in patients with renal dysfunction 3
• Never use rectal suppositories or enemas in neutropenic or thrombocytopenic patients 3, 2