What is the recommended bowel regimen for patients with chronic constipation?

Recommended Bowel Regimen for Chronic Constipation

For adults with chronic idiopathic constipation, start with polyethylene glycol (PEG) 17g daily as first-line pharmacological therapy, with fiber supplementation (particularly psyllium >10g/day) reserved for mild symptoms or as adjunctive therapy. 1

Stepwise Treatment Algorithm

Step 1: Initial Assessment and Lifestyle Modifications

• Assess dietary fiber intake to determine if supplementation is needed (target 14g fiber per 1,000 kcal intake) 1
• Increase fluid intake, particularly in patients in the lowest quartile of daily fluid consumption 1
• Encourage scheduled toileting after meals to utilize the gastrocolic reflex 1

Step 2: First-Line Pharmacological Therapy

Polyethylene Glycol (PEG) - Preferred Initial Agent:

• Dosing: 17g daily mixed in 8 ounces of liquid 1
• Mechanism: Osmotic laxative that increases stool frequency by 2.90 complete spontaneous bowel movements per week compared to placebo 1
• Duration: Response is durable over 6 months 1
• Cost: $10-45/month 1
• Side effects: Abdominal distension, loose stool, flatulence, nausea 1

Alternative: Fiber Supplementation (for mild constipation):

• Best evidence supports psyllium at doses >10g/day for at least 4 weeks 1, 2
• Critical: Must ensure adequate hydration (8-10 ounces fluid with each dose) 1
• Limitation: Flatulence is common; avoid finely ground wheat bran which can harden stool 1
• Note: Fiber is less effective than PEG but reasonable for patients with low dietary fiber intake 1

Step 3: Second-Line Therapies (if PEG inadequate)

Osmotic Laxatives:

• Lactulose: 15g daily, only osmotic agent studied in pregnancy 1
• Magnesium oxide: 400-500mg daily (caution in renal insufficiency) 1

Stimulant Laxatives (short-term or rescue):

• Bisacodyl: 5-10mg daily (maximum 10mg/day) 1
• Senna: 8.6-17.2mg daily 1
• Important caveat: Recommended for short-term use only; prolonged use can cause electrolyte imbalance and diarrhea 1

Step 4: Prescription Secretagogues (refractory cases)

When first and second-line therapies fail:

• Linaclotide: 145mcg daily for CIC (72mcg alternative dose based on tolerability); increases to 290mcg for IBS-C 1, 3

  • Cost: $523/month 1
  • May benefit abdominal pain 1

• Plecanatide: 3mg daily 1

  • Cost: $526/month 1

• Lubiprostone: 24mcg twice daily 1

  • Cost: $374/month 1

• Prucalopride: 1-2mg daily (5-HT4 agonist) 1

  • Cost: $563/month 1

Step 5: Specialized Interventions

For opioid-induced constipation specifically:

• Methylnaltrexone: 0.15mg/kg subcutaneously every other day (maximum once daily) 1
• Contraindication: Do not use in postoperative ileus or mechanical bowel obstruction 1

For suspected pelvic floor dysfunction:

• Consider pelvic floor rehabilitation/biofeedback 4

Critical Clinical Pitfalls

Rule out impaction before escalating therapy:

• Check for fecal impaction, especially if diarrhea accompanies constipation (overflow) 1
• If impacted: glycerin suppository, mineral oil retention enema, or manual disimpaction with pre-medication (analgesic ± anxiolytic) 1

Rule out mechanical obstruction:

• Perform physical exam and consider abdominal x-ray before adding stimulant laxatives 1

Avoid common errors:

• Do not add stool softeners (docusate) to stimulant laxatives - less effective than laxative alone 1
• Do not use supplemental medicinal fiber (psyllium) for opioid-induced constipation - ineffective 1
• Avoid long-term magnesium-based laxatives due to potential toxicity, especially in renal insufficiency 1, 5

Goal of Therapy

Target: One non-forced bowel movement every 1-2 days 1