What is the generic name for MiraLAX (polyethylene glycol 3350) and how should it be administered to an elderly patient?

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Last updated: October 28, 2026 • View editorial policy

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MiraLAX Generic Name and Administration in Elderly Patients

MiraLAX's generic name is polyethylene glycol 3350 (PEG 3350), and it should be administered to elderly patients at 17 g once daily, mixed in 8 ounces (approximately 240 mL) of any beverage 1, 2.

Generic Name

  • Polyethylene glycol 3350 (PEG 3350) is the active pharmaceutical ingredient
  • Available as an over-the-counter osmotic laxative 1
  • Acts as a long-chain polymer of ethylene oxide that works osmotically 1

Dosing in Elderly Patients

Standard Dosing

  • 17 g once daily is the FDA-approved dose for occasional constipation 1
  • Mix the powder in 8 ounces of liquid (water or any beverage) 1, 2
  • The powder is unflavored and grit-free, dissolving in any beverage 2

Efficacy in Elderly Population

The 2023 AGA-ACG guidelines demonstrate that PEG 3350 is equally effective and safe in elderly patients as in younger adults 1. In clinical trials:

  • 117 patients aged 65 and older were enrolled
  • 84-94% of elderly patients were treated successfully across different observation months 3
  • Response was durable over 12 months with no evidence of tachyphylaxis 3

Safety Profile in Elderly

PEG 3350 has an excellent safety profile in elderly patients with no clinically significant electrolyte disturbances 3, 4:

  • No changes in serum electrolytes, calcium, glucose, BUN, or creatinine over 12 months 3
  • Minimal systemic absorption (only 0.19-0.25% urinary excretion) 4
  • 93% eliminated via feces 4
  • No dose adjustment needed for age or mild renal impairment 4

Duration of Treatment

  • While FDA-approved for "occasional constipation," efficacy and safety are proven for up to 6-12 months of continuous use 1, 3
  • Response is durable over time without loss of effectiveness 1, 3

Expected Side Effects

Common gastrointestinal effects (generally mild to moderate) 1:

  • Diarrhea or loose stools
  • Abdominal distension/bloating
  • Flatulence
  • Nausea

Important: These side effects decrease markedly after the first week of treatment 5

Clinical Advantages

  • No prescription required - available over-the-counter 1
  • Relatively inexpensive 1
  • Can be used earlier in the treatment algorithm, either after or in combination with fiber supplementation 1
  • Superior efficacy compared to tegaserod and similar or greater efficacy than lactulose 1, 6

Key Caveat

While generally very safe, there has been one case report of potential ethylene glycol contamination in generic PEG 3350 products causing acute kidney injury 7. However, this appears to be an isolated contamination issue rather than an inherent problem with the medication itself.

References

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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.