Miralax Dosages: Your GoodRx Guide

Irregular. Stopped-up. Clogged. No matter what you call it, constipation affects a lot of us. In the U.S., about 16% of adults have constipation symptoms. If you’re looking at over-the-counter (OTC) options for relief, you may be considering Miralax (polyethylene glycol 3350).

If you decide to try Miralax, it’s important to know exactly how much to take. Below, we cover everything you need to know about choosing the right Miralax dosage.

What’s the typical Miralax dosage for adults?

Miralax treats occasional constipation. It comes as a powder and can be dissolved in any beverage (hot, cold, or room temperature). You can buy Miralax as pre-measured, single-use packets or as a bottle of powder with a measuring cup in the cap.

The typical Miralax dosage for adults and adolescents age 17 and older is:

• Dissolve 17 grams (one capful or one packet) in 4 oz to 8 oz of your preferred beverage.

• Stir well to fully dissolve the powder, then drink.

• Take once daily as needed for up to 7 days.

Miralax is considered a gentle laxative. It takes about 1 to 3 days to start working. Keep in mind that taking more Miralax than recommended won’t make it work faster. Miralax is only meant for occasional use when you take it without a healthcare professional’s guidance. Talk to your healthcare team if you need to take Miralax for longer than 7 days in a row.

What’s the typical Miralax dosage for children?

Miralax is only FDA approved for people age 17 and older. However, many healthcare professionals prescribe it off-label for younger children. Talk with your child’s pediatrician before using Miralax for kids. They can help you choose the best laxative for your child.

Promotion disclosure

Miralax (Polyethylene Glycol 3350 Non-Prescription)

Avg retail price

$12.52(Save 63.02%)

GoodRx discount

$4.63

Compare all prices

If your child’s pediatrician recommends Miralax, be sure to clarify how much to give. You should also ask how long you should give it to them. There is no standard dosing for this age group.

Are there any dosage adjustments for medical conditions?

Some health conditions may require dose changes, closer monitoring, or avoiding Miralax altogether. Check in with your healthcare team if you have any of the conditions below.

Kidney problems

Our kidneys have the important job of balancing fluids and electrolytes in the body. Miralax works by keeping extra water in the intestines. But this shift in water can also cause a shift in electrolytes for people with kidney problems or kidney disease. Depending on your kidney function, your healthcare team may recommend more monitoring or a different laxative.

People with kidney problems might still be able to take Miralax at the standard dose. But it’s best to ask a healthcare professional before using it. The manufacturer of Miralax has not provided any standard dose adjustments for people with kidney problems. So your dose would be unique based on your specific situation.

Bowel problems

Miralax shouldn’t be used if you have certain bowel conditions, including:

• Bowel obstruction (current or previous)

• Inflammatory bowel disease (IBD)

• A perforated bowel (a hole in the bowel wall)

EXPERT PICKS: WHAT TO READ NEXT

• When does Miralax start working? Get the answer to this and other frequently asked questions about Miralax.

• What to expect: Learn about common and rare Miralax side effects, as well as how to manage them.

• What to drink for constipation: Read about the best drinks that can relieve constipation, plus which ones to avoid.

A bowel obstruction (blocked intestine) includes symptoms like nausea, vomiting, or abdominal pain along with constipation. Call your healthcare team for next steps if you’re experiencing these symptoms, especially if they’re severe.

Trouble swallowing liquids

If you need to thicken liquids to prevent choking, you can still take Miralax. But you need to pay attention to what’s in your thickener. Although Miralax can be dissolved in most beverages, it interacts with starch-based thickeners and can prevent them from working.

If you need to use Miralax with a thickening agent, use thickeners containing xanthan gum instead of starch. If these thickeners aren’t an option for you, discuss alternative constipation medications with your healthcare team.

What happens if you miss a dose of Miralax?

Miralax is generally taken once a day as needed. If you forget a dose, you can either skip it or take it later that day. But don’t take extra Miralax to make up for missed doses.

What should you do if you take too much Miralax?

The biggest risk of taking too much Miralax is diarrhea. And diarrhea can lead to dehydration. Keep in mind that it can take up to 3 days to have a bowel movement after taking Miralax. So it’s important to be patient and give it enough time to work. Talk to your healthcare team if Miralax doesn’t seem to be working at the standard dose, or if you need to take it daily for longer than 7 days.

How to save on Miralax

There are ways to save on Miralax, which is available as both a brand-name and generic medication. By having a healthcare professional write a prescription for OTC Miralax, GoodRx can help you save over 90% off the average retail price. Generic Miralax's price at certain pharmacies is less than $14.08 with a free GoodRx discount.

Frequently asked questions

Why trust our experts?

Written by:

Tegan Smedley, PharmD, APh

Tegan Smedley, PharmD, APh, has 10 years of experience as a pharmacist. She has worked in a variety of settings, including retail, hospital, and ambulatory care.

Edited by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

Reviewed by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

Our editorial standards

Meet our experts