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Polyethylene Glycol 3350

Medically reviewed by Last updated on Aug 5, 2021.


(pol i ETH i leen GLY kol 3350)

Index Terms

  • Macrogol
  • PEG

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product

Kit, Oral:

Gialax: [contains aspartame, polyethylene glycol (interact starch), tartrazine (fd&c yellow #5)]

Packet, Oral:

HealthyLax: 17 g/dose (1 ea, 14 ea, 100 ea) [contains polyethylene glycol (interact starch)]

MiraLax: 17 g/dose (1 ea [DSC], 10 ea, 12 ea [DSC], 24 ea) [contains polyethylene glycol (interact starch)]

Generic: 17 g/dose (1 ea, 14 ea, 30 ea, 100 ea)

Powder, Oral:

GaviLAX: 17 g/dose (238 g, 510 g) [contains polyethylene glycol (interact starch)]

GlycoLax: 17 g/dose (119 g, 255 g, 527 g) [contains polyethylene glycol (interact starch)]

MiraLax: 17 g/dose (1 ea, 119 g, 238 g, 510 g, 765 g) [contains polyethylene glycol (interact starch)]

PEGyLAX: 17 g/dose (527 g [DSC]) [contains polyethylene glycol (interact starch)]

Generic: 17 g/dose (119 g, 238 g, 255 g, 510 g, 527 g, 850 g)

Brand Names: U.S.

  • GaviLAX [OTC]
  • Gialax
  • GlycoLax [OTC]
  • HealthyLax [OTC]
  • MiraLax [OTC]

Pharmacologic Category

  • Laxative, Osmotic


An osmotic agent, polyethylene glycol 3350 causes water retention in the stool; increases stool frequency.


Minimal (<0.28%; Pelham, 2008)


Feces (93%); urine (0.2%) (Pelham, 2008)

Onset of Action

Oral: 24 to 96 hours

Use: Labeled Indications

Constipation, occasional: Treatment of occasional constipation

Off Label Uses

Bowel preparation before colonoscopy

Based on the Consensus Document on Bowel Preparation Before Colonoscopy from The American Society of Colon and Rectal Surgeons (ASCRS), The American Society for Gastrointestinal and Endoscopy (ASGE), and The Society of American Gastrointestinal and Endoscopic Surgeons (SAGES), polyethylene glycol 3350 in combination with bisacodyl delayed-release tablets or magnesium citrate is effective and recommended for bowel preparation before colonoscopy [Wexner 2006].


Hypersensitivity to polyethylene glycol or any component of the formulation; known or suspected bowel obstruction

OTC labeling: When used for self-medication, do not use if you have renal disease unless advised by a health care provider

Canadian labeling: Additional contraindications (not in US labeling): Relaxa: Use in children <18 years of age unless advised by a physician

Dosing: Adult

Bowel preparation before colonoscopy (off-label use): Oral: 17 g (~1 heaping tablespoon) in 240 mL (8 ounces) of clear liquid every 10 minutes until 2,000 mL of volume are consumed (start within 6 hours after administering bisacodyl delayed-release tablets or magnesium citrate) (ASCRS/ASGE/SAGES [Wexner 2006])

Constipation, occasional: Oral: 17 g (~1 heaping tablespoon) dissolved in 120 to 240 mL (4 to 8 ounces) of beverage, once daily; do not use for >1 to 2 weeks (product specific) unless directed by health care provider. In a clinical trial, 34 g once daily was shown to be effective, but with increased adverse effects (DiPalma 1999).

Dosing: Geriatric

Refer to adult dosing.

Dosing: Pediatric

Bowel preparation: Limited data available: Children >2 years and Adolescents: Oral: 1.5 g/kg/day for 4 days; maximum daily dose: 100 g/day (Pashankar 2004)

Constipation: Limited data available: Infants, Children, and Adolescents: Oral: 0.2 to 0.8 g/kg/day (NASPGHAN [Tabbers] 2014); higher initial dose of 1 g/kg have been suggested ( Loening-Buck 2004; Pashankar 2001); maximum daily dose: 17 g/day. Note: Dosage should be individualized to achieved desired effect, infants and young children may require higher doses than school aged children (Loening-Buck 2004; Pashankar 2001)

Fecal impaction, slow disimpaction: Limited data available: Children and Adolescents: Oral: 1 to 1.5 g/kg daily for 3 to 6 consecutive days (NASPGHAN [Tabbers] 2014; Youssef 2002); maximum daily dose: 100 g/day (Youssef 2002); following disimpaction maintenance dose of 0.4 g/kg daily should be continued for ≥ 2 months (NASPGHAN [Tabbers] 2014)


Dissolve powder completely in 120 to 240 mL (4 to 8 ounces) of water, juice, soda, coffee, or tea.



Constipation, occasional: Stir powder in 120 to 240 mL (4 to 8 ounces) of water, juice, soda, coffee, or tea until dissolved and administer immediately.

Bowel preparation for colonoscopy (off-label use): Administer bisacodyl delayed-release tablets or magnesium citrate prior to polyethylene glycol administration. After bowel movement (or up to 6 hours later if no bowel movement), stir powder in 240 mL (8 ounces) of clear liquid until dissolved and administer immediately. Dose is repeated every 10 minutes until 2,000 mL of volume is consumed.


Store at 20°C to 25°C (68°F to 77°F); excursions are permitted between 15°C to 30°C (59°F to 86°F).

Drug Interactions

Dichlorphenamide: Laxatives may enhance the hypokalemic effect of Dichlorphenamide. Monitor therapy

Digoxin: Polyethylene Glycol 3350 may decrease the serum concentration of Digoxin. Monitor therapy

Adverse Reactions

The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.

>10%: Gastrointestinal: Gastrointestinal signs and symptoms (32%; Di Palma 2007), diarrhea (11%; DiPalma 2006)

1% to 10%: Gastrointestinal: Flatulence (7%; DiPalma 2006), nausea (6%; DiPalma 2006), abdominal pain (5%; DiPalma 2006), loose stools (4%; DiPalma 2006), abdominal distention (3%; DiPalma 2006)

Frequency not defined.

Gastrointestinal: Dyspepsia (Di Palma 2007), eructation (Di Palma 2007), stomach discomfort (Di Palma 2007)

Hematologic & oncologic: Rectal hemorrhage (Di Palma 2007)


Concerns related to adverse effects:

• Electrolyte imbalance: Prolonged, frequent, or excessive use may lead to electrolyte imbalance.

• Hypersensitivity: Do not use if you are hypersensitive to polyethylene glycol. If an allergic reaction develops (eg, rash, swelling, difficulty breathing), discontinue use immediately and seek medical care.

Disease-related concern:

• Bowel obstruction: Evaluate patients with symptoms of bowel obstruction, appendicitis, or inflamed bowel (nausea, vomiting, abdominal pain or distension) prior to use; use is contraindicated in patients with known or suspected bowel obstruction.

• Renal impairment: Use with caution in patients with renal impairment. Do not use in renal impairment unless under supervision of a health care professional.

Other warnings/precautions:

• Administration: If severe diarrhea occurs, discontinue use. When used for bowel preparation for colonoscopy (off-label use), oral medications should not be administered within 1 hour of start of therapy.

• Duration of therapy: Do not use for longer than 1 to 2 weeks (product specific); 2 to 4 days may be required to produce bowel movement.

• OTC labeling: When used for self-medication, patients should consult health care provider prior to use if they have nausea, vomiting, or abdominal pain, irritable bowel syndrome, or a sudden change in bowel habits for >2 weeks. Patients should be instructed to discontinue use and consult health care provider if they have severe diarrhea, rectal bleeding, if abdominal pain, bloating, cramping, or nausea gets worse, or if need to use for >1 week.

Pregnancy Considerations

Polyethylene glycol (PEG) has minimal systemic absorption and would be unlikely to cause fetal malformations. Treatment of constipation in pregnant women is similar to that of nonpregnant patients and medications may be used when diet and lifestyle modifications are not effective. Polyethylene glycol may be used when an osmotic laxative is needed (Gomes 2018; Shin 2015).

Patient Education

What is this drug used for?

• It is used to treat constipation.

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

• Abdominal pain

• Abdominal cramps

• Bloating

• Nausea

• Passing gas

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Severe dizziness

• Passing out

• Diarrhea

• Rectal bleeding

• Rectal pain

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.

Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions.

Consumer Information Use and Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a limited summary of general information about the medicine's uses from the patient education leaflet and is not intended to be comprehensive. This limited summary does NOT include all information available about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not intended to provide medical advice, diagnosis or treatment and does not replace information you receive from the healthcare provider. For a more detailed summary of information about the risks and benefits of using this medicine, please speak with your healthcare provider and review the entire patient education leaflet.

Frequently asked questions

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.