What is the recommended management for a patient with constipation (reduced bowel movements) occurring 2-3 times a week?

Management of Reduced Bowel Movements (2-3 Weekly)

Start with polyethylene glycol (PEG) 17 grams mixed in 8 ounces of liquid once daily as first-line pharmacologic therapy, as this has the strongest evidence for efficacy with moderate certainty and increases complete spontaneous bowel movements by 2.90 per week. 1

Initial Assessment

Before initiating treatment, rule out the following:

• Fecal impaction (especially if diarrhea accompanies constipation, suggesting overflow around impaction) 1, 2
• Bowel obstruction via physical exam and consider abdominal x-ray 1, 2
• Metabolic causes: hypercalcemia, hypokalemia, hypothyroidism, diabetes mellitus 1, 2
• Constipating medications that can be discontinued 1

First-Line Treatment Algorithm

Step 1: Lifestyle Modifications + PEG

• Increase fluid intake to at least 8-10 ounces with each medication dose, particularly if baseline intake is low 1, 2
• Increase physical activity if feasible 1, 2
• Start PEG 17 grams mixed in 8 ounces of liquid once daily 1, 2
  • Goal: 1 non-forced bowel movement every 1-2 days 1, 2
  • Response is durable over 6 months 1, 2
  • Side effects include abdominal distension, loose stool, flatulence, and nausea 1

Step 2: Add Fiber (Optional for Mild Cases)

• Consider fiber supplementation before or in combination with PEG for mild constipation 1, 2
• Psyllium has the best evidence among fiber types, requiring doses >10 grams/day for at least 4 weeks 3
• Avoid bulk-forming agents as monotherapy for medication-induced constipation without adequate fluid intake 2
• Fiber increases stool frequency but commonly causes flatulence 3

Second-Line Treatment (If Constipation Persists After 1-2 Weeks)

Step 3: Add Stimulant Laxative

• Add bisacodyl 10-15 mg orally daily to three times daily 1, 2
• Alternative: Senna 2 tablets twice to three times daily 1, 2, 4
  • Generally causes bowel movement in 6-12 hours 4
• Continue PEG alongside stimulant laxative 2

Third-Line Treatment (Refractory Constipation)

Step 4: Additional Laxatives

If constipation persists, reassess for impaction or obstruction, then consider adding: 1, 2

• Lactulose 30-60 mL twice to four times daily 1
• Magnesium hydroxide 30-60 mL daily to twice daily 1
• Magnesium citrate 8 ounces daily 1

Step 5: Rectal Interventions

For severe constipation or impaction: 1, 2

• Bisacodyl suppository 10 mg rectally once to twice daily 1, 2
• Glycerin suppository 1, 2
• Fleet, saline, or tap water enema 1, 2
• Manual disimpaction following pre-medication with analgesic ± anxiolytic 1

Step 6: Prokinetic Agent

If gastroparesis is suspected: 1, 2

• Metoclopramide 10-20 mg orally four times daily 1, 2
• Note: Chronic use may be limited due to risk of tardive dyskinesia 1

Important Clinical Caveats

• Stool softeners alone (docusate) are less effective than stimulant laxatives and should not be used as monotherapy 1
• Adequate fluid intake (1.5-2.0 liters/day) significantly enhances the effect of fiber on stool frequency 5
• Probiotics with prebiotic fiber may provide additional benefit in specific populations (e.g., Parkinson's disease) but evidence is limited for general constipation 1
• For opioid-induced constipation, prophylactic stimulant laxatives should be started immediately, and methylnaltrexone 0.15 mg/kg subcutaneously every other day can be considered for refractory cases 1
• Treatment duration matters: Fiber supplementation requires at least 4 weeks at doses >10 grams/day to show benefit 3