MiraLAX's Dosage: What to Know

Medically Reviewed By Victor Nguyen, PharmD, MBA

MiraLAX: Introduction

MiraLAX is a brand-name over-the-counter (OTC) medication that contains the active drug polyethylene glycol 3350. It belongs to a class of drugs called osmotic laxatives. MiraLAX is available in a generic form.

This medication is approved by the Food and Drug Administration (FDA) to treat occasional constipation. It is approved for use in adults and children ages 17 years and older.

In this article, you’ll find information about MiraLAX’s dosage and details on how to take the drug. For a comprehensive overview of MiraLAX, view this article.

Finding a healthcare professional

If you want to find a healthcare professional to discuss whether MiraLAX is right for you, search here.

This article describes typical recommended dosages for MiraLAX. These dosages are provided by the drug’s manufacturer.

Always follow the dosage of MiraLAX listed in the drug label information.

MiraLAX: Adult dosage

This section presents commonly recommended dosage for MiraLAX in adults. (For information about the drug’s dosage in children, see the “MiraLAX: Pediatric dosage” section below.)

If you have questions about MiraLAX’s dosage, ask your doctor or pharmacist. They can recommend the dosage that’s best for you.

MiraLAX’s form and strength

MiraLAX comes as a powder for dissolving in liquid. You’ll swallow the liquid solution.* MiraLAX is available in the following:

  • bottle, which has a strength of 17 grams (g) per capful
  • packets, which has a strength of 17 g per packet

* See the “MiraLAX: How to take” section below for information on preparing the liquid solution.

Typical recommended dosage

The overview below shows the recommended MiraLAX powder dosage for adults.

MiraLAX dosage for constipation

The recommended dosage of MiraLAX for constipation is:

  • Dose: 17 g, which is for dissolving in liquid*
  • Frequency: once per day

The recommended maximum dosage is 17 g taken once per day for 7 days.

* See the “MiraLAX: How to take” section below for information on preparing the liquid solution.

Length of treatment

MiraLAX is for short-term use to treat occasional constipation. Follow the recommended maximum dosage described just above and do not exceed it.

If your constipation lasts for more than 7 days, call your doctor. They can recommend ways to help manage it.

MiraLAX: Pediatric Dosage

This section presents the commonly recommended dosage for MiraLAX in children. (For information about the drug’s dosage in adults, see the “MiraLAX: Adult dosage” section above.)

If you have questions about MiraLAX’s dosage, ask your child’s doctor or a pharmacist. They can recommend the dosage that’s best for your child.

MiraLAX’s form and strength

MiraLAX comes as a powder for dissolving in liquid. You’ll swallow the liquid solution.* MiraLAX is available in the following:

  • bottle, which has a strength of 17 grams (g) per capful
  • packets, which has a strength of 17 g per packet

* See the “MiraLAX: How to take” section below for information on preparing the liquid solution.

Typical recommended dosage

The overview below shows the recommended MiraLAX powder dosage for children.

MiraLAX dosage for constipation

The recommended dosage of MiraLAX for constipation is as follows.

Child’s age Dose Frequency
17 years and older 17 g, which is for dissolving in liquid* once per day
16 years and younger ask a doctor ask a doctor

The recommended maximum dosage is 17 g taken once per day for 7 days.

* See the “MiraLAX: How to take” section below for information on preparing the liquid solution.

Length of treatment

MiraLAX is for short-term use to treat occasional constipation. Follow the recommended maximum dosage described just above and don’t exceed it.

If constipation lasts for more than 7 days, call your child’s doctor. They’ll recommend ways to help manage it.

MiraLAX: Common questions about dosage

Below are some common questions related to MiraLAX’s dosage.

Does MiraLAX have a dosage chart?

Yes, it does. See the dosage chart for children in the “MiraLAX: Pediatric dosage” section directly above.

If you have additional questions about MiraLAX’s dosage, ask your doctor or pharmacist.

Is MiraLAX dosage calculated in teaspoons or tablespoons?

It’s not calculated in either of those measures. The MiraLAX dosage is calculated in grams (g). You’ll use 17 g of the powder to make a drinkable solution. That means you’ll use one capful of the MiraLAX bottle or one MiraLAX packet.

If you have additional questions about the dosage of MiraLAX, ask your doctor or pharmacist.

What is the MiraLAX dosage for colonoscopy prep?

MiraLAX is approved to treat occasional constipation in adults and children ages 17 years and older. However, doctors may recommend MiraLAX off-label as part of colonoscopy preparation. Off-label means a doctor recommends a drug for a purpose other than what it’s approved to treat.

Ask your doctor if you’d like more information about taking MiraLAX for colonoscopy preparation.

Can MiraLAX dosage be calculated by a person’s weight?

No, MiraLAX dosage is not calculated by weight of the person taking it. For its approved use, the recommended dosage is 17 g to be taken once per day.

MiraLAX is used to treat occasional constipation. The recommended maximum dosage is 17 g taken once per day for 7 days.

Ask your doctor or pharmacist if you have questions about the dosage of MiraLAX.

MiraLAX: Dosage considerations

Several factors should be considered before taking MiraLAX. These factors include:

  • your other medical conditions
  • other symptoms you’re experiencing
  • your pregnancy status
  • prescription medications you take

Ask your doctor or pharmacist for more information about these factors before taking MiraLAX.

MiraLAX: How to take

MiraLAX comes as a powder for dissolving in liquid. You’ll swallow the liquid solution.

To make the solution, you will need a 4-ounce (oz) to 8-oz beverage. (It can be hot, cold, or at a room temperature of 68°F to 77°F [20°C to 25°C].) You’ll completely dissolve 17 grams (g) of MiraLAX powder in the beverage and then drink it.

You can take MiraLAX with or without food.

Ask your doctor or pharmacist if you have questions about how to take MiraLAX.

MiraLAX: Overdose

For some drugs, taking more than the recommended dosage may lead to unwanted side effects or overdose. Do not take more MiraLAX than the drug label information states. Also, do not take more MiraLAX than your doctor or pharmacist recommends.

What to do if you take too much MiraLAX

Call your doctor or pharmacist if you think you’ve taken too much of this drug. Also, you can call the American Association of Poison Control Centers at 800-222-1222 or use its online tool. However, if your symptoms are severe, call 911 or a local emergency number. Or go to the nearest emergency room right away.

MiraLAX: What to discuss with your doctor

Talk with your doctor or pharmacist for additional information about MiraLAX’s dosage. Keep in mind that the dosages presented in this article are typical dosages provided by the drug’s manufacturer. Your doctor can recommend the dosage of MiraLAX that’s right for you and your condition. Always follow the dosage that your doctor recommends for you.

In addition to discussing MiraLAX with your doctor, you may find the following articles helpful in learning more.

  • Overview of MiraLAX. For comprehensive details on MiraLAX, see this article.
  • Drug comparison. To learn how MiraLAX compares with Metamucil, read this article.
  • Information on side effects. If you’d like to know about possible side effects of MiraLAX, view this article.
  • Details about constipation. To learn more about constipation, which MiraLAX is used to treat, see this article.

Disclaimer: Healthgrades has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.


Medical Reviewer: Victor Nguyen, PharmD, MBA
Last Review Date: 2022 Nov 22
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