What is the approach to managing constipation?

Approach to Constipation

Start with polyethylene glycol (PEG) 17g dissolved in 8 ounces of liquid once daily as first-line pharmacological treatment, combined with lifestyle modifications including ≥1.5 liters of fluid daily and regular physical activity. 1, 2

Initial Lifestyle Modifications

Before or alongside pharmacological treatment, implement these specific measures:

• Fluid intake: Ensure at least 1.5 liters of water daily, with increased intake during exercise, hot weather, or illness 2
• Physical activity: Encourage regular exercise and mobility within the patient's physical limits 2
• Toileting habits: Establish regular attempts at defecation 30 minutes after meals to synergize with the gastrocolic reflex 3, 2
• Positioning: Use a small footstool during defecation to achieve a more natural squatting position that facilitates bowel movements 2
• Access and privacy: Ensure adequate toilet access and privacy, particularly critical for elderly or mobility-impaired patients 2
• Medication review: Discontinue or substitute medications that cause constipation before proceeding with extensive workup 3, 2

First-Line Pharmacological Treatment: PEG

PEG is the gold standard first-line agent with the strongest evidence base and should be initiated before other pharmacological options. 1, 2

• Dosing: 17g dissolved in 8 ounces of liquid once daily 1, 2
• Efficacy: Increases complete spontaneous bowel movements (CSBMs) by approximately 2.9 per week compared to placebo, with durable response over 6 months 1, 2
• Side effects: Abdominal distension, loose stool, flatulence, and nausea 1, 2
• Cost: Approximately $1 per day, making it highly cost-effective 3, 2
• Evidence quality: Strong recommendation with moderate certainty of evidence from both AGA and ACG 1, 2

Fiber Supplementation

Fiber can be used before, with, or instead of PEG for mild constipation, though evidence quality is lower:

• Psyllium has the best evidence for efficacy among fiber supplements, though still low quality 1
• Dosing: Psyllium 15g daily is effective and costs approximately $1 per day 3
• Critical caveat: Inadequate fluid intake with fiber supplementation can worsen constipation—patients must maintain adequate hydration 2
• Avoid in specific populations: Bulk-forming laxatives should be avoided in non-ambulatory elderly patients with low fluid intake due to increased risk of mechanical obstruction 4
• Best for: Patients with mild-to-moderate symptoms, especially those with diets deficient in fiber 1
• Common side effect: Flatulence 1

Second-Line Options

If PEG is ineffective after an adequate trial (at least 4 weeks):

• Alternative osmotic laxatives: Lactulose or milk of magnesia (1 oz twice daily, approximately $1 per day) 3, 2
• Stimulant laxatives: Senna, bisacodyl, or sodium picosulfate—particularly useful for opioid-induced constipation 1, 2
• Combination approach: Supplement osmotic agents with stimulant laxatives (e.g., bisacodyl or glycerin suppositories), preferably administered 30 minutes after a meal to synergize with the gastrocolonic response 3
• Caution with magnesium: Saline laxatives containing magnesium (e.g., magnesium hydroxide/milk of magnesia) should be used cautiously in elderly patients due to risk of hypermagnesemia, particularly in those with renal impairment 4

Prescription Agents for Refractory Cases

When symptoms do not respond to over-the-counter laxatives, consider newer prescription agents:

• Strongly recommended: Linaclotide, plecanatide, and prucalopride for patients who don't respond to over-the-counter options 1
• Conditionally recommended: Lubiprostone 1
• Cost consideration: These agents cost $7-$9 per day (at time of guideline development), significantly more than first-line options 3
• Linaclotide dosing: 145 mcg once daily for chronic idiopathic constipation in adults; 290 mcg once daily for IBS-C 5

When to Perform Diagnostic Testing

After discontinuing constipating medications and performing basic blood tests as guided by clinical features, perform a therapeutic trial with fiber and/or laxatives before ordering anorectal testing. 3, 2

• Anorectal tests are indicated for patients who do not respond to over-the-counter agents 3, 2
• High-quality evidence supports performing anorectal tests in non-responders rather than empirically continuing laxatives 3

Management of Defecatory Disorders

Pelvic floor retraining by biofeedback therapy rather than laxatives is the treatment of choice for defecatory disorders. 3, 2

• Efficacy: Improves symptoms in more than 70% of patients with defecatory disorders 3, 2
• Strong recommendation with high-quality evidence from AGA 3
• Mechanism: Trains patients to relax pelvic floor muscles during straining and correlate relaxation with pushing to achieve defecation 3
• Success factors: Motivation of patient and therapist, frequency and intensity of retraining program, and involvement of behavioral psychologists and dietitians as necessary 3

Special Population: Opioid-Induced Constipation

• All patients receiving opioid analgesics should be prescribed a concomitant laxative unless contraindicated by pre-existing diarrhea 2
• First-line treatment: Stimulant laxatives (senna, bisacodyl) or osmotic laxatives (PEG, lactulose) 2
• Refractory cases: Methylnaltrexone, a peripherally acting μ-opioid antagonist, can be considered for opioid-induced constipation that persists despite laxative therapy 1

Special Population: Elderly Patients

• PEG 17g daily is the preferred agent due to efficacy and good safety profile 4
• Pay particular attention to medication lists: Polypharmacy is a major contributor to constipation in elderly patients 2
• Ensure adequate toilet access especially for patients with decreased mobility 4
• Avoid liquid paraffin in bed-bound patients and those with swallowing disorders due to risk of aspiration lipoid pneumonia 4
• For swallowing difficulties or repeated fecal impaction: Rectal measures (suppositories or enemas) may be preferred, with isotonic saline enemas being safer than sodium phosphate enemas 4

Management of Slow-Transit Constipation

Normal transit constipation (NTC) and slow-transit constipation (STC) can be safely managed with long-term use of laxatives (strong recommendation, moderate-quality evidence). 3

For medically refractory slow-transit constipation:

• Surgical option: Total colectomy with ileorectal anastomosis, but only after well-documented STC and failure of aggressive, prolonged trial of laxatives, fiber, and prokinetic agents 3
• Critical exclusions: Must exclude coexistent upper gastrointestinal motility disorders and defecatory disorders to maximize outcome 3
• Realistic expectations: Patients need to understand the procedure treats constipation but other symptoms (e.g., abdominal pain) may not necessarily be relieved 3
• Rare indication: Even in tertiary centers with strong surgical referrals, only 5% of highly selected patients justify surgical treatment 3

Management of Fecal Impaction

• In the absence of suspected perforation or bleeding: Manage with disimpaction followed by maintenance bowel regimen to prevent recurrence 2

Common Pitfalls to Avoid

• Docusate monotherapy is ineffective for prevention or treatment and should be reserved only for very specific situations where other options are contraindicated or unavailable 2, 4
• Inadequate trial periods: Avoid premature escalation to more aggressive options before ensuring adequate trial of first-line agents (at least 4 weeks) 1, 2
• Inadequate fluid intake with fiber: This can worsen constipation rather than improve it 2
• Ignoring medication review: Failing to identify and address constipating medications leads to unnecessary treatment escalation 2