What is the best next step for a patient with constipation?

Management of Constipation

For patients with constipation, the best next step is to initiate a stimulant laxative such as bisacodyl 10-15 mg daily to three times daily or senna with a goal of one non-forced bowel movement every 1-2 days. 1, 2

Initial Assessment

• Rule out impaction, obstruction, and other treatable causes such as hypercalcemia, hypokalemia, hypothyroidism, and diabetes mellitus 1, 2
• Discontinue any non-essential constipating medications that may be contributing to symptoms 1, 2
• Perform a digital rectal examination to assess for fecal impaction, which would require different initial management 1

Non-Pharmacological Interventions

• Increase fluid intake and encourage physical activity when appropriate 1, 2
• Ensure privacy and comfort for defecation, with proper positioning (using a footstool may help) 1
• Increase dietary fiber if the patient has adequate fluid intake and physical activity 1, 2
• Abdominal massage can be efficacious in reducing gastrointestinal symptoms, particularly in patients with neurogenic problems 1

Pharmacological Management Algorithm

First-Line Treatment

• Start with stimulant laxatives: bisacodyl 10-15 mg daily to TID or senna 1, 2
• Evidence suggests that stimulant laxatives alone may be sufficient without stool softeners 3
• For opioid-induced constipation, prophylactic laxatives should be prescribed concomitantly 1

Second-Line Treatment (If First-Line Fails)

• Add osmotic laxatives such as:
  • Polyethylene glycol (PEG) 17g with 8 oz water once or twice daily 1, 2, 4
  • Lactulose 30-60 mL BID-QID 1, 2
  • Magnesium hydroxide 30-60 mL daily-BID (use with caution in renal impairment) 1, 2

Third-Line Treatment (For Refractory Constipation)

• For impaction: glycerine suppositories, mineral oil retention enema, or manual disimpaction if necessary 1, 2
• For opioid-induced constipation: consider peripherally acting μ-opioid receptor antagonists such as methylnaltrexone 0.15 mg/kg subcutaneously every other day 1, 2
• For suspected gastroparesis: consider adding a prokinetic agent such as metoclopramide 10-20 mg PO QID 1, 2

Special Considerations

• For elderly patients: ensure access to toilets, educate patients to attempt defecation 30 minutes after meals, and consider PEG (17 g/day) which has a good safety profile 1, 2
• Avoid liquid paraffin for bed-bound patients due to risk of aspiration 1, 2
• Use magnesium salts cautiously in patients with renal impairment due to risk of hypermagnesemia 1, 2
• Avoid bulk laxatives (e.g., psyllium) in non-ambulatory patients with low fluid intake due to risk of mechanical obstruction 1, 2
• Bulk laxatives are not recommended for opioid-induced constipation 1

Monitoring and Follow-up

• Assess response to treatment with a goal of one non-forced bowel movement every 1-2 days 1, 2
• PEG achieves its best results when used between one and two weeks 4
• If diarrhea occurs, discontinue or reduce the dose of laxatives 4
• For patients with persistent symptoms despite treatment, consider referral for specialized testing such as colonic transit studies or anorectal manometry 1, 5