Treatment of Adult Constipation
Start with polyethylene glycol (PEG) 17g daily as first-line pharmacological therapy after initial lifestyle modifications, and escalate to prescription secretagogues (linaclotide or plecanatide) if symptoms persist after 4-12 weeks. 1, 2
Initial Non-Pharmacological Management
- Begin with increased fluid intake, dietary fiber supplementation, regular exercise, and scheduled toileting after meals 1, 2
- Psyllium fiber at doses >10g/day for at least 4 weeks shows the strongest evidence among fiber supplements, though this receives only conditional recommendation 1, 3
- Pectin is an alternative fiber option with demonstrated efficacy 3
- Avoid supplemental fiber in medication-induced constipation (such as clozapine), as it may worsen the condition 4
Pharmacological Treatment Algorithm
First-Line: Over-the-Counter Agents
Polyethylene glycol (PEG) receives the strongest recommendation as initial pharmacological therapy:
- Start PEG 17g once daily (can be increased to twice daily if needed) 1, 2, 4
- PEG demonstrates durable response over 6 months with moderate-quality evidence 2
- Continue for 4-12 weeks before considering escalation to prescription agents 1, 2
- PEG is inexpensive, widely available, and well-tolerated, making it the optimal first-line choice 2
Second-Line: Prescription Secretagogues (Strong Recommendations)
If PEG fails after 4-12 weeks, escalate to prescription agents:
Linaclotide 145 mcg once daily receives strong recommendation for chronic idiopathic constipation 1, 2, 5
Plecanatide receives strong recommendation as an alternative secretagogue with similar mechanism to linaclotide 1, 2
Prucalopride (serotonin type 4 agonist) receives strong recommendation for chronic idiopathic constipation 1, 2
Lubiprostone receives only conditional recommendation (weaker evidence) 1, 2
Alternative and Rescue Therapies
Stimulant laxatives for short-term or rescue use:
- Sodium picosulfate receives strong recommendation for short-term use (≤4 weeks) or rescue therapy 1, 2
- Bisacodyl 10-15 mg receives strong recommendation for short-term use (≤4 weeks) or rescue therapy 1, 2, 4
- Senna receives only conditional recommendation with low-quality evidence 1, 2
Other osmotic laxatives (conditional recommendations):
- Lactulose receives conditional recommendation 1, 2
- Magnesium oxide receives conditional recommendation but must avoid in renal impairment—check creatinine clearance before prescribing 1, 2
Critical Clinical Pitfalls to Avoid
- Do not continue escalating osmotic laxative doses indefinitely—switch to prescription agents after 4-12 weeks if inadequate response 2
- Rule out mechanical bowel obstruction before escalating laxative therapy, particularly with prominent fecal loading on imaging 2
- Avoid magnesium-based laxatives in renal impairment—check creatinine clearance before prescribing 2
- Confirm adequate trial of current medications for at least 4 weeks before switching 2
Management of Refractory Constipation
- If PEG is inadequate after 4-6 weeks, add or switch to a prescription secretagogue 2
- Consider anorectal testing to evaluate for defecatory disorders in patients who do not respond to over-the-counter agents 6
- Colonic transit studies and manometry can identify colonic dysmotility in select cases 6
- Biofeedback therapy is effective for defecatory disorders 6
- Colectomy may be necessary for specific patients with slow-transit constipation refractory to medical management 6
Cost and Accessibility Considerations
- PEG is inexpensive and widely available, making it the optimal first-line choice 2
- Prescription secretagogues and prokinetics are more expensive but have strong evidence for efficacy when over-the-counter agents fail 2
- The 2023 AGA-ACG guidelines used the GRADE Evidence to Decision framework, which considered costs and health equity in formulating recommendations 1, 2