What is the first-line treatment for constipation?

First-Line Treatment for Constipation

The first-line treatment for constipation includes fiber supplementation, particularly psyllium, followed by polyethylene glycol (PEG) as osmotic laxative when fiber is insufficient. 1

Initial Approach: Fiber Supplementation

• Fiber supplements are recommended as first-line therapy for constipation, especially for individuals with low dietary fiber intake 2, 1
• Among fiber supplements, psyllium has the strongest evidence for effectiveness and should be prioritized 1
• Psyllium generally produces a bowel movement within 12 to 72 hours 3
• Adequate hydration must be maintained with fiber supplementation to prevent worsening of constipation 1
• Common side effects include flatulence, which patients should be warned about 2

Second Step: Osmotic Laxatives

• If fiber supplementation is insufficient, polyethylene glycol (PEG) is strongly recommended as the next step 2, 1
• PEG has moderate certainty of evidence supporting its effectiveness 2
• PEG typically produces a bowel movement within 1 to 3 days 4
• Response to PEG has been shown to be durable over 6 months of continuous use 2
• Side effects include abdominal distension, loose stool, flatulence, and nausea 2

Third Step: Stimulant Laxatives

• When osmotic laxatives fail to provide adequate relief, stimulant laxatives such as senna or bisacodyl can be added 2, 1
• Stimulant laxatives like senna are effective for treatment of chronic idiopathic constipation 2
• The goal is to achieve one non-forced bowel movement every 1-2 days 1

Special Considerations

For Opioid-Induced Constipation

• Unless contraindicated by pre-existing diarrhea, all patients receiving opioid analgesics should be prescribed a concomitant laxative 2
• Osmotic or stimulant laxatives are generally preferred for opioid-induced constipation 2
• Bulk laxatives such as psyllium are not recommended for opioid-induced constipation 2

For Elderly Patients

• Particular attention should be paid to the assessment of elderly patients 2
• PEG (17 g/day) offers an efficacious and tolerable solution with a good safety profile 2
• Avoid liquid paraffin for bed-bound patients and those with swallowing disorders due to risk of aspiration 2
• Saline laxatives (e.g., magnesium hydroxide) should be used with caution because of the risk of hypermagnesemia, especially in those with renal impairment 2

Common Pitfalls to Avoid

• Failure to assess total fiber intake before recommending additional fiber can lead to inadequate treatment 1
• Not ensuring adequate hydration when increasing fiber intake can worsen constipation 1
• Using bulk laxatives in patients with opioid-induced constipation is ineffective 2
• Expecting immediate results from fiber supplementation (may take 12-72 hours) or PEG (may take 1-3 days) 4, 3
• Failure to recognize that complete symptom resolution is often not achievable, which must be made clear to patients to manage expectations 2