What is the recommended bowel regimen for managing constipation?

Bowel Regimen for Constipation

For chronic idiopathic constipation in adults, start with polyethylene glycol (PEG) 17g once daily as first-line therapy, which provides superior efficacy and safety compared to other laxatives. 1

First-Line Treatment Algorithm

Mild Constipation (Fiber-Deficient Diet)

• Psyllium 5-10g daily (divided into 1-3 doses) can be tried initially for mild symptoms, taken with 8-10 ounces of fluid per dose 1, 2
• Psyllium increases spontaneous bowel movements by 2.32 per week and improves global symptom relief (RR 1.86) 2
• Key limitation: Fiber causes flatulence and requires adequate fluid intake; avoid in patients with low fluid consumption 1

Moderate-to-Severe Constipation (Recommended Starting Point)

• PEG 17g in 8 oz water once daily is the recommended first-line agent 1, 3
• PEG increases complete spontaneous bowel movements by 2.90 per week (95% CI 2.12-3.68) and total bowel movements by 2.30 per week 1
• Response is durable over 6 months with minimal side effects (abdominal distension, loose stool, flatulence, nausea) 1
• Can dose twice daily (17g BID) if once daily is insufficient 3

Second-Line Options for Persistent Constipation

Stimulant Laxatives

• Bisacodyl 10-15mg daily, targeting one non-forced bowel movement every 1-2 days 1, 3
• Can increase to 10-15mg two to three times daily for persistent symptoms 3
• Senna 15-30mg daily (typically 2 tablets twice daily) as alternative stimulant 3, 4
• Critical warning: Prolonged stimulant use causes colonic dependency and rebound constipation; transition to osmotic agents if needed long-term 5

Alternative Osmotic Laxatives

• Lactulose 30-60mL twice to four times daily 5
• Magnesium hydroxide 30-60mL daily to twice daily 5
• Caution: Avoid magnesium-based laxatives in renal impairment due to hypermagnesemia risk 3, 5

Rectal Interventions for Impaction

When fecal impaction is identified on digital rectal exam:

• Glycerin suppository as first-line rectal intervention 3
• Bisacodyl suppository 10mg rectally once or twice daily 3
• Manual disimpaction with premedication (analgesic ± anxiolytic) if suppositories fail 3

Prescription Therapies for Refractory Cases

Intestinal Secretagogues (IBS-C or Refractory CIC)

• Linaclotide 145mcg once daily for chronic idiopathic constipation (can reduce to 72mcg for tolerability) 1, 6
• Linaclotide 290mcg once daily for IBS with constipation 6
• Take on empty stomach at least 30 minutes before meals 6
• Most efficacious secretagogue available, though diarrhea is common side effect 1

Alternative Secretagogues

• Lubiprostone (chloride channel activator) - less likely to cause diarrhea than linaclotide but nausea is frequent 1
• Plecanatide or tenapanor - similar efficacy to linaclotide with comparable diarrhea rates 1

Opioid-Induced Constipation Specific Management

• Start prophylactic stimulant laxative with first opioid dose 3
• Combine stimulant (senna or bisacodyl) with stool softener as indicated 1
• For laxative-refractory cases: Methylnaltrexone 0.15mg/kg subcutaneously every other day (maximum once daily) 1, 3
• Contraindication: Do NOT use fiber/psyllium in opioid-induced constipation as it may worsen symptoms 4

Essential Supportive Measures

• Increase fluid intake to at least 2 liters daily - particularly critical for those in lowest quartile of fluid consumption 1, 3, 5
• Encourage physical activity within patient limitations 1, 3
• Dietary fiber increase only if adequate fluid intake maintained 5
• Ensure toilet access and educate patients to attempt defecation twice daily, 30 minutes after meals, straining no more than 5 minutes 5

Critical Pitfalls to Avoid

• Always rule out bowel obstruction, fecal impaction, hypercalcemia, hypokalemia, hypothyroidism, and diabetes before escalating therapy 1, 5
• Never use enemas in patients with recent colorectal or gynecological surgery 3
• Avoid bulk-forming laxatives in postoperative patients with limited mobility or fluid intake due to obstruction risk 3
• Discontinue stimulant laxatives immediately if rebound constipation develops and transition to PEG 5
• Fiber requires 4+ weeks at doses >10g/day for optimal effect - inadequate trial duration is common error 2