What are the treatment options for chronic constipation?

Treatment of Chronic Constipation

Start with fiber supplementation (specifically psyllium) as first-line therapy, followed by polyethylene glycol (PEG) 17g daily if fiber is insufficient, then escalate to prescription secretagogues or prokinetics if these fail. 1, 2

Stepwise Treatment Algorithm

Step 1: Fiber Supplementation

• Begin with psyllium 14g per 1,000 kcal intake per day as it is the only fiber supplement with solid evidence for effectiveness in chronic idiopathic constipation 1, 3, 4
• Ensure adequate hydration with 8-10 ounces of fluid with each fiber dose to prevent worsening constipation 3, 4
• Assess total dietary fiber intake before adding supplements—patients already consuming adequate fiber may not benefit from additional supplementation 1, 3
• Gradually titrate fiber over several days to minimize flatulence, bloating, and abdominal discomfort 1, 5
• Evidence for other fibers (bran, inulin, methylcellulose) is very limited or nonexistent 1

Step 2: Osmotic Laxatives

• If fiber supplementation fails, advance to polyethylene glycol (PEG) 17g daily mixed in 8 ounces of liquid 1, 2, 4
• PEG increases complete spontaneous bowel movements by approximately 2.9 per week and demonstrates durable response over 6 months 4
• Side effects include abdominal distension, loose stool, flatulence, and nausea 2
• Alternative osmotic laxatives if PEG is not tolerated: magnesium oxide 400-500mg daily or lactulose 15g daily 3, 4
• Avoid magnesium-containing laxatives in patients with renal insufficiency due to risk of hypermagnesemia 4

Step 3: Stimulant Laxatives (Short-Term or Rescue)

• Use bisacodyl 10-15mg 2-3 times daily or senna when first-line treatments fail, targeting one non-forced bowel movement every 1-2 days 1, 3
• Do not rely on stimulant laxatives for chronic therapy—long-term safety is unknown and prolonged use carries risk of electrolyte imbalance 4
• Consider rectal bisacodyl once daily if oral route is inadequate 1

Step 4: Prescription Secretagogues and Prokinetics

• Linaclotide 145 mcg daily for chronic idiopathic constipation when PEG provides inadequate response 4, 6
• Linaclotide increases CSBM frequency by approximately 1.5 per week and improves stool consistency and straining 6
• Lubiprostone 24 mcg twice daily is FDA-approved for chronic idiopathic constipation in adults 7
• Lubiprostone activates chloride channels to enhance intestinal fluid secretion and can be combined with peripherally acting μ-opioid receptor antagonists 1, 7
• Prucalopride 1-2mg daily is a prokinetic agent for patients not responding to PEG 4

Special Populations and Circumstances

Opioid-Induced Constipation

• Methylnaltrexone 0.15 mg/kg every other day (maximum once daily) for constipation unresponsive to standard laxatives 1
• Methylnaltrexone relieves opioid-induced constipation while preserving opioid-mediated analgesia 1
• Contraindicated in postoperative ileus or mechanical bowel obstruction 1, 2
• Naloxegol is another peripherally-acting μ-opioid receptor antagonist option for chronic opioid use 1
• Lubiprostone is FDA-approved for opioid-induced constipation in adults with chronic non-cancer pain, though effectiveness with methadone is not established 7

Gastroparesis

• Add metoclopramide as a prokinetic agent if gastroparesis is suspected 1
• Erythromycin has shown some success for constipation symptoms not responding to peripherally acting μ-opioid receptor antagonists 1

Fecal Impaction

• Administer glycerine suppositories or perform manual disimpaction 1

Critical Pitfalls to Avoid

• Failure to assess baseline dietary fiber intake before recommending supplements can lead to excessive fiber consumption without benefit 1, 3
• Inadequate hydration with fiber supplementation will worsen constipation rather than improve it 3, 4
• Using stimulant laxatives as chronic maintenance therapy exposes patients to unknown long-term risks and potential electrolyte disturbances 4
• Prescribing magnesium-containing laxatives to patients with renal insufficiency risks dangerous hypermagnesemia 4
• Using methylnaltrexone in mechanical bowel obstruction or postoperative ileus is contraindicated and potentially harmful 1, 2
• Abrupt initiation of high-dose fiber causes bloating and abdominal pain—always titrate gradually over several days 1, 5