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Polyethylene glycol 3350

Brand names: MiraLAX, GlycoLax

Polyethylene glycol 3350 (MiraLAX) is a gentle laxative that draws water into the stool to relieve constipation.

Brand namesMiraLAX, GlycoLax
Type of medicineOsmotic laxative
Prescription?Over the counter
ImportantThis page is general information, not a prescription. Don't start, stop, or change a medicine without talking to your provider or pharmacist.

Overview

It usually works in 1 to 3 days. Higher doses are used as bowel prep before a colonoscopy.

What it's used for

  • Occasional constipation
  • Bowel prep before a colonoscopy (as directed)

How to take it

  • Stir the powder into 4 to 8 ounces of a drink until dissolved, then drink it.
  • Follow the label; don't use it longer than 7 days unless a provider says to.
  • For children, ask a provider for the right amount.

Your dose depends on your health and other medicines. Always follow your prescription label, and ask your pharmacist if anything is unclear.

Side effects

Common side effects

  • Bloating or gas
  • Belly cramps
  • Loose stools
Call your provider todayBloody stools or bleeding from the rectum
Call your provider todaySevere or worsening belly pain or swelling
Call your provider todayDiarrhea that won't stop

Warnings

  • See a provider if you have nausea, vomiting, or belly pain, or a sudden change in bowel habits lasting 2 weeks.
  • Don't use it if you could have a bowel blockage.

Other medicines, foods, and alcohol

  • Few interactions.

Tell your provider and pharmacist about every medicine, vitamin, and supplement you take.

Pregnancy and breastfeeding

Commonly used for constipation in pregnancy. Ask your provider.

Missed doses, overdose, and storage

If you miss a dose

This medicine is often taken only when needed. If you take it on a schedule, take a missed dose when you remember, unless it's almost time for the next one. Don't double up.

If someone takes too much

Call Poison Control at 1-800-222-1222 or get help online at poison.org. Call 911 if the person collapses, has a seizure, has trouble breathing, or can't be woken.

Storing it

Store at room temperature, away from heat and moisture (not in the bathroom), and out of reach of children and pets.

Conditions it's used for

Sources

Last updated 2026-11-13.