What are the effects of Polyethylene Glycol (PEG) toxicity, associated with MiraLAX (Polyethylene Glycol 3350)?

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Last updated: April 8, 2025View editorial policy

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From the Guidelines

MiraLAX (polyethylene glycol 3350) is generally safe with minimal risk of toxicity when used as directed, as evidenced by recent clinical guidelines 1. The standard adult dose is 17 grams (about 1 heaping tablespoon) dissolved in 8 ounces of liquid once daily for up to 7 days. For children, dosing should be determined by a healthcare provider. If overdose is suspected, discontinue use immediately and seek medical attention, especially if symptoms are severe or persistent. Treatment typically involves supportive care with fluid and electrolyte replacement. MiraLAX works by drawing water into the intestines to soften stool and increase bowel movements, but doesn't get absorbed into the bloodstream significantly, which contributes to its safety profile 1. However, patients with kidney disease, electrolyte imbalances, or intestinal obstruction should consult healthcare providers before use. Some key considerations for the use of MiraLAX include:

  • It is recommended for the treatment of chronic idiopathic constipation (CIC) by the American Gastroenterological Association and the American College of Gastroenterology 1.
  • PEG has been shown to be efficacious in individuals with CIC for up to 6 months 1.
  • Side effects may include bloating, flatulence, and diarrhea, but these are typically mild or moderate 1.
  • PEG is widely available without the need for a prescription and is relatively inexpensive, making it a reasonable option for earlier use in the algorithm for the management of CIC 1. While MiraLAX is available over-the-counter, prolonged use beyond 7 days should be discussed with a healthcare provider to rule out underlying conditions requiring different treatment. It's also important to note that a trial of fiber supplement can be considered for mild constipation before PEG use or in combination with PEG 1. Overall, the benefits of MiraLAX in treating constipation, as supported by recent clinical guidelines 1, outweigh the risks when used appropriately.

From the Research

MiraLAX Toxicity

  • There is no direct evidence of MiraLAX toxicity in the provided studies 2, 3, 4, 5, 6.
  • However, the studies suggest that polyethylene glycol (PEG), the active ingredient in MiraLAX, is generally safe and well-tolerated in both adults and children when used to treat constipation and fecal impaction 2, 3, 4, 6.
  • One study noted that PEG without electrolytes was associated with a lower plasma sodium level, but this difference was not considered clinically significant 2.
  • Another study found that PEG with electrolytes was well-tolerated and effective in treating severe constipation and fecal impaction, with a low incidence of adverse events 3.
  • A review of 58 publications on the use of PEG in functional constipation and fecal impaction found that PEG with or without electrolytes was more efficacious than placebo and had a good safety profile 4.
  • A study on the long-term use of stimulant laxatives, which are different from PEG, found that they were associated with harmful long-term colonic effects and possible carcinogenic risk, but this does not directly relate to MiraLAX toxicity 5.
  • A study on the use of PEG without electrolytes in children with constipation and encopresis found that it was well-tolerated and effective, with no clinically significant side effects 6.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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