MiraLAX (polyethylene glycol 3350) is a brand-name powder that’s mixed into a beverage and taken by mouth. It’s available over the counter and can be used for constipation or before a colonoscopy as a bowel preparation.

MiraLAX can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

These are just a few of the more common side effects reported by people who took MiraLAX in clinical trials:

  • bloating
  • gas
  • nausea
  • diarrhea or loose stools
  • stomach cramping*

* For more information about this side effect, see “Side effect specifics.”

Mild side effects can occur with MiraLAX use. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to MiraLAX’s drug review.

Mild side effects that have been reported with MiraLAX include:

  • bloating
  • gas
  • nausea
  • diarrhea or loose stools
  • rectal bleeding
  • stomach cramping*

These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you develop a side effect while taking MiraLAX and want to tell the FDA about it, visit MedWatch.

* For more information about this side effect, see “Side effect specifics.”

MiraLAX may cause serious side effects. Serious side effects aren’t common, but they can occur. The list below may not include all possible serious side effects of the drug. For more information, you can refer to MiraLAX’s drug review.

If you develop serious side effects while taking MiraLAX, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Serious side effects that have been reported include:

* For more information about this side effect, see “Side effect specifics” below.

ALLERGIC REACTION

For some people, MiraLAX can cause an allergic reaction.

In general, symptoms of allergic reaction can be mild or serious.

Ways to manage

For mild allergic reaction symptoms, such as a mild rash, call your doctor right away. They may recommend treatments to help manage your symptoms. They’ll also let you know whether you should keep taking the medication.

For severe allergic reaction symptoms, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms require immediate medical care because they can become life threatening. If you’ve had a serious allergic reaction to MiraLAX, your doctor may recommend taking a different medication instead.

MiraLAX may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

What are the long-term side effects of MiraLAX?

If you take MiraLAX every day, you may experience long-term side effects from the drug. Examples of these side effects may include gas or bloating. Side effects from MiraLAX may decrease over time. For example, if you take MiraLAX for a long time, your body may adjust to the drug, and you may experience fewer side effects. But, if you take MiraLAX short term, the side effects will go away once you stop treatment with MiraLAX.

If you have questions about long-term side effects or how long MiraLAX side effects last, talk with your doctor. If you’re concerned about side effects, be sure to discuss your treatment plan with your doctor. They can also help determine if you can take MiraLAX every day for your condition.

What are the MiraLAX side effects in kids?

The same side effects that can occur in adults taking MiraLAX may also occur in children. This includes symptoms such as gas, bloating, nausea, or stomach cramps. More serious side effects like dehydration are dangers of MiraLAX for adults and for children.

It’s important to note that MiraLAX is not approved for use in children under 17 years old. Using this medication in children under this age is considered an “off-label” use. Off-label use is when a drug is used for a different condition or at a different dosage than the FDA has approved.

Be sure to talk with your child’s doctor before treating them with MiraLAX. They can discuss side effects that may occur from this medication and make sure it’s the best treatment option for your child.

What are the side effects of overuse of MiraLAX?

Over-the-counter use of MiraLAX is only recommended for short-term use. It’s not recommended to use this medication for longer than 1 week. If you are constipated for longer than 1 week, it’s recommended that you see a doctor to see what may be causing the constipation.

In some cases, doctors may recommend using MiraLAX long-term to manage constipation. In this case, you may take this medication every day. But it’s still important that you only take the dose that’s recommended by your doctor. Taking too much MiraLAX can cause serious side effects, including dehydration, which may lead to complications like electrolyte imbalance. If you think you may have taken too much MiraLAX, see a doctor or call a Poison Control Center right away.

Learn more about some of the side effects that MiraLAX may cause. To find out how often side effects occurred in clinical trials, see the manufacturer’s website.

Dehydration

It’s possible to experience dehydration from taking MiraLAX. Dehydration was not a common side effect that people taking this medication reported in studies. However, it still may occur, and it may be more common in older adults or younger children.

You should be aware of symptoms of dehydration so that you can tell your doctor right away if you experience them. Symptoms may include:

What you can do

If you have symptoms of dehydration, be sure to tell your doctor right away. Your doctor can help you to increase your fluid intake and may also recommend stopping MiraLAX treatment. In this case, they may recommend a different treatment option for you.

Before taking MiraLAX, discuss your health history with your doctor. MiraLAX may not be right for you if you have certain medical conditions or other factors affecting your health. Be sure to talk with your doctor if any of the following apply to you:

Disclaimer: Medical News Today 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.