From the Guidelines
Miralax (polyethylene glycol 3350) should be dosed at 17 grams (about 1 heaping tablespoon or one capful of powder) dissolved in 8 ounces of water, juice, or other beverage, taken once daily for the treatment of occasional constipation, as recommended by the most recent guidelines 1. This dose is appropriate for adults and children 17 years and older. The medication usually works within 1-3 days. For children under 17, dosing should be determined by a healthcare provider, though a common pediatric dose is 0.5-1.5 g/kg/day.
Key Considerations
- Miralax works as an osmotic laxative by drawing water into the colon, softening stool and increasing bowel movements.
- It's generally considered safe for short-term use (up to 7 days for over-the-counter use) and doesn't typically cause dependency or urgent bowel movements like stimulant laxatives.
- The powder should be completely dissolved before drinking, and maintaining adequate hydration while taking Miralax is important.
- If constipation persists beyond 7 days of use, consult a healthcare provider as this may indicate a more serious condition requiring medical evaluation.
Additional Guidance
- According to the American Gastroenterological Association-American College of Gastroenterology clinical practice guideline, PEG 3350 has been shown to be efficacious in individuals with chronic idiopathic constipation for up to 6 months 1.
- The NCCN Guidelines for Adult Cancer Pain Panel Members recommend a stimulant laxative or a heaping tablespoon (17 g) of polyethylene glycol with 8 oz of water 2 times daily along with maintaining adequate fluid intake for prophylaxis in patients taking opioids 1. However, the most recent guideline from 1 supports once daily dosing for occasional constipation.
From the FDA Drug Label
(Bottle Only) (white section in cap) (17 g) (cold, hot or room temperature) then drink adults and children 17 years of age and older: use once a day stir and dissolve one packet of powder (17 g) in any 4 to 8 ounces of beverage (cold, hot or room temperature) then drink do not use more than 7 days children 16 years of age or under: ask a doctor
The recommended dosing for Miralax is to use once a day. For adults and children 17 years of age and older, stir and dissolve one packet of powder (17 g) in any 4 to 8 ounces of beverage. The treatment should not exceed 7 days. For children 16 years of age or under, it is recommended to ask a doctor 2.
From the Research
Miralax Dosing
- Miralax, also known as polyethylene glycol (PEG), is an osmotic laxative used to treat constipation.
- According to a systematic review published in 2005 3, there is good evidence to support the use of PEG for the treatment of chronic constipation.
- A study published in 2021 4 found that PEG 3350 is an effective and safe therapy for both long and short term treatment of pediatric functional constipation.
- The maximum daily dose of PEG was 17g in a study comparing its effectiveness with Senna in children with anorectal malformation 5.
- A systematic review published in 2021 6 found good evidence to recommend PEG as a first-line laxative for the treatment of chronic constipation.
- Another study published in 2022 7 also supported the use of PEG-based preparations as first-line laxatives, with good evidence suggesting their short- and long-term efficacy.