What are the treatment options for chronic constipation?

Treatment of Chronic Constipation

Start with fiber supplementation (particularly psyllium) for mild symptoms, then escalate to polyethylene glycol (PEG) if inadequate response, followed by prescription secretagogues like linaclotide or lubiprostone for refractory cases. 1, 2

Stepwise Treatment Algorithm

First-Line: Fiber Supplementation

• Psyllium is the preferred fiber supplement with the strongest evidence for effectiveness in chronic idiopathic constipation (CIC), though the overall certainty of evidence remains low 1, 2
• Assess total dietary fiber intake before recommending supplementation to avoid inadequate treatment 1, 2
• Standard dosing requires 8-10 ounces of fluid with each dose to prevent worsening constipation 1, 2
• Common side effect is flatulence; bloating may occur with highly fermentable fibers 1
• Use fiber as first-line therapy particularly in patients with low baseline dietary fiber intake 1

Second-Line: Polyethylene Glycol (PEG)

• PEG is strongly recommended when fiber fails, with moderate certainty of evidence showing durable response over 6 months 1, 2
• PEG increases complete spontaneous bowel movements by 2.90 per week and spontaneous bowel movements by 2.30 per week compared to placebo 1
• Dosing: 17 grams mixed in 8 ounces of liquid once daily 1
• Side effects include abdominal distension, loose stool, flatulence, and nausea 1, 2
• PEG can be used in combination with fiber for additive benefit 1

Third-Line: Prescription Secretagogues

Linaclotide (Linzess)

• Strong recommendation with moderate certainty of evidence for patients inadequately responding to over-the-counter agents 3
• Increases complete spontaneous bowel movements by 1.37 per week and provides 3-fold increase in responder rates versus placebo 3
• Dosing: 145 mcg once daily on empty stomach, 30+ minutes before first meal; can reduce to 72 mcg if diarrhea occurs 3
• Particularly useful when abdominal bloating, discomfort, or pain coexist with constipation due to dual mechanism addressing both motility and visceral pain 3
• Can be used as replacement for or adjunct to PEG 3
• Diarrhea is most common adverse effect (4.7% discontinuation rate) 3

Lubiprostone

• Conditional recommendation with low certainty of evidence for adults with CIC not responding to over-the-counter agents 4, 5
• Activates chloride channels to enhance intestinal fluid secretion without directly stimulating smooth muscle 4, 5
• Dosing: 24 mcg twice daily with food and water for CIC 4, 5
• Nausea occurs in up to 30.9% of patients but is reduced when taken with food 4, 5
• Monthly cost approximately $374, higher than over-the-counter options 4

Fourth-Line: Stimulant Laxatives

• Bisacodyl can be used when first-line treatments fail, with goal of one non-forced bowel movement every 1-2 days 2
• Should be used temporarily rather than as chronic therapy 6

Critical Implementation Considerations

Hydration Requirements

• Focus fluid intake increases on patients in the lowest quartile of daily fluid consumption, as they are most likely to be constipated 1
• Standard fiber doses require 8-10 ounces of fluid to prevent paradoxical worsening 1, 2
• Daily intake of 2 liters of water enhances positive effects of fiber 7

Common Pitfalls to Avoid

• Never start combination therapy (e.g., linaclotide + PEG) simultaneously in treatment-naive patients; begin with PEG first, then add linaclotide if needed to avoid excessive response 3
• Do not recommend fiber without ensuring adequate hydration, as this can worsen constipation 1, 2
• Avoid lubiprostone in patients with severe diarrhea or known/suspected mechanical gastrointestinal obstruction 5
• Methylcellulose lacks evidence despite widespread use 1
• Bran has very uncertain effects with very low certainty of evidence 1

Special Populations

• For opioid-induced constipation in chronic non-cancer pain, consider lubiprostone 24 mcg twice daily or peripherally acting μ-opioid receptor antagonists like methylnaltrexone 2, 4, 5
• Methylnaltrexone contraindicated in postoperative ileus or mechanical bowel obstruction 2
• Lubiprostone effectiveness not established for methadone-induced constipation 5

Cost and Access Considerations

• Most over-the-counter options (fiber, PEG) are low-cost and readily accessible 1
• Prescription agents may require prior authorization and have significant out-of-pocket costs depending on insurance coverage 1, 4
• Generic formulations not available for all prescription options 1

Monitoring and Duration

• Periodically reassess need for continued therapy rather than indefinite prescribing 5
• Response to PEG is durable over 6 months; long-term safety data for prescription agents is limited 1