Can MiraLAX (polyethylene glycol 3350) be used to treat constipation?

MiraLAX (Polyethylene Glycol 3350) for Constipation

Yes, MiraLAX (polyethylene glycol 3350) is recommended for the treatment of constipation with a standard dose of 17 grams dissolved in 8 ounces of liquid once daily. 1

Mechanism of Action and Efficacy

• PEG 3350 is an osmotic laxative that works by retaining water in the stool, softening it and increasing the frequency of bowel movements 2
• First bowel movements typically occur within 24-48 hours, with complete results usually seen within 1-2 weeks 2
• Clinical studies show PEG 3350 is significantly more effective than placebo:
  • 78.3% success rate for medication-induced constipation vs. 39.1% for placebo 3
  • 52% overall treatment success for chronic constipation vs. 11% for placebo in long-term (6-month) use 4
  • Increases complete spontaneous bowel movements by approximately 2.9 per week 1

Dosing Guidelines

• Standard dose: 17 grams (one heaping tablespoon) dissolved in 4-8 ounces of water, juice, soda, coffee, or tea once daily 2
• For severe constipation requiring rapid relief: 68 grams has been shown to be effective within 24 hours without significant adverse effects 5
• Treatment duration:
  • Recommended for up to 2 weeks for occasional constipation 2
  • Safe for up to 6 months for chronic constipation based on clinical trials 4

Patient Selection

• Appropriate for:

  • Adults with occasional or chronic constipation 1, 2
  • Medication-induced constipation 3
  • Irritable bowel syndrome with constipation (IBS-C) 6
  • Cancer patients with opioid-induced constipation 6

• Not recommended for:

  • Children (unless prescribed by a physician) 2
  • Pregnant women (unless prescribed by a physician) 2
  • Patients with symptoms of bowel obstruction 2
  • Patients with allergies to polyethylene glycol 2

Safety Profile

• Well-tolerated with minimal side effects 1, 4
• Most common side effects include:
  • Abdominal distension
  • Flatulence
  • Nausea
  • Loose stools 1
• No significant changes in laboratory values (electrolytes, calcium, renal function) with use 5, 4
• No evidence of tachyphylaxis (diminished response over time) 2

Clinical Pearls

1. For opioid-induced constipation, PEG 3350 is recommended as part of a prophylactic bowel regimen 6
2. Ensure adequate hydration during treatment to maximize effectiveness 1
3. For persistent constipation, the dose can be increased or combined with other laxatives such as bisacodyl or magnesium-based products 6, 1
4. Before initiating treatment for chronic constipation, consider screening for underlying causes such as hypercalcemia, hypothyroidism, and celiac disease 1
5. PEG 3350 can be used after a trial of fiber supplementation or in combination with fiber for chronic idiopathic constipation 1

Common Pitfalls to Avoid

• Taking more than the prescribed dose may cause severe diarrhea and fluid loss 2
• Discontinue use and consult a physician if unusual cramps, bloating, or diarrhea occur 2
• Do not use in patients with suspected bowel obstruction 6
• Avoid using docusate (stool softener) in combination with PEG 3350, as studies show no additional benefit 6

PEG 3350 represents a safe, effective, and well-tolerated option for managing constipation across various patient populations with minimal risk of significant adverse effects.