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Constipation treatment.

Resting among the myriad of over-the-counter (OTC) medications available to treat constipation in infants and children is the little-known powder polyethylene glycol (sold as MiraLAX). Prior to October 2006, polyethylene glycol was available by prescription only, but after much review, it landed on the FDA's Rx-to-OTC Switch List and started appearing on drugstore shelves throughout the country.


Although polyethylene glycol is only FDA approved for patients age 17 and up, clinicians now prescribe the medication more often to treat constipation in infants and children. As clinical experience with polyethylene glycol increases in our pediatric population, so does awareness of its OTC existence. For this reason, it seems appropriate to provide a brief discussion about this medication.

Why the Doctor Might Prescribe Polyethylene Glycol

Clinicians would prescribe polyethylene glycol to your child to treat impaction and constipation that is not related to a serious illness (i.e. gastrointestinal disease, diabetes, cystic fibrosis, etc.). Constipation can be defined as a delay in defecation or difficulty in having a bowel movement for more than two weeks.

Polyethylene glycol can be used for both acute and chronic constipation. Impaction would be described as a condition where dry, hard stools form into a mass that collects in the rectum. The mass makes it very difficult, if not impossible, to have a bowel movement.

Once the impacted stool has been evacuated or if impaction was not present to begin with, maintenance therapy would be implemented to help your child sustain normal bowel movements. Polyethylene glycol used for maintenance therapy will improve stool frequency and/or consistency and ease your child's pain and discomfort.

The dose needed to bring about disimpaction will be higher than that used in maintenance therapy; but nonetheless, polyethylene glycol has been proven to be an effective option in both scenarios.

Mechanism of Action

Polyethylene glycol falls into the class of medications known as osmotic laxatives. The way the medication works is very straight-forward: it decreases the amount of water absorbed from your intestines, which thereby increases the amount of water in your stools. This increase of water content in your stools makes the stool softer and easier to pass.

It may take less than a day for polyethylene glycol to do its job, but do not be surprised if it takes two to three days for your child to have a bowel movement. If faster relief is needed, it may be a good idea to explore other medication options!

Precautions and Side Effects

Adverse reactions to polyethylene glycol may include cramping, abdominal bloating, gas, diarrhea and nausea. Serious adverse reactions to polyethylene glycol are not common at all. There is a very rare chance that your child could be allergic to polyethylene glycol, in which case your child may present with hives, rash, dizziness, difficulty breathing, or swelling of the face, tongue, or throat. The medication should be discontinued and a physician should be consulted if an allergic reaction does occur.

There is limited information from quality studies on the use of polyethylene glycol in children less than two years of age. That's not to say this medication should not be used in infants. In fact, prescribers have been progressively increasing their orders of polyethylene glycol for babies less than six months old even without the evidence from strong studies. Just be sure to keep an extra watchful eye on your infant if he is given polyethylene glycol!

In the case of chronic constipation, you should wean your child off polyethylene glycol once the goal of therapy--about one soft stool per day--is achieved (it may take months to get to this point). Taper the dose down every two weeks until daily movements continue without the laxative. If you discontinue the polyethylene glycol cold turkey, then hard stools will likely recur!

Other Common Osmotic Laxatives

Lactulose, sorbitol, Milk of Magnesia, and magnesium citrate are all osmotic laxatives that work like polyethylene glycol. Studies show they all have comparable efficacy, but recent findings suggest that polyethylene glycol has fewer side effects and greater acceptance by children.

The increasing comfort in using polyethylene glycol in infants and children is good news because magnesium citrate and Milk of Magnesia may cause concern since there is a possible risk of magnesium poisoning in the littlest patients. In addition, Lactulose and sorbitol have a terrible taste, whereas polyethylene glycol doesn't. Polyethylene glycol is a well-accepted medication by an otherwise finicky group of patients!


Although polyethylene glycol is available over the counter and gaining ground in its use in infants and children, I would recommend bringing your child to her physician before starting this medication to address the underlying constipation. If the physician decides the issue needs to be treated, then it may be in your child's best interest to start with behavior modification and dietary changes before bringing polyethylene glycol on board.

Once it's determined that a medication is needed to help relieve your child's constipation, typical age-based dosing used in clinical practice is as follows:

* Younger than 18 months-1/2 to 1 teaspoon once daily

* 18 months to 3 years-2 to 3 teaspoons once daily

* Older than 3 years-2 to 4 teaspoons once daily

(There are specific weight-based dosing guidelines available, but I would verify the dose with your child's physician or pharmacist just to be sure you are giving your child a safe, yet effective, amount.)

The teaspoon measurements refer to the amount of polyethylene glycol powder you would mix with four to eight ounces of water, juice, or other flavored beverage (hot, cold, or room temperature). The mixture can be taken without regard to meals and at any point during the day.

MiraLAX cost about $20 for a 30-dose supply, so if your child's physician suggests buying it over the counter, first try asking for a prescription instead because most insurance companies still cover the prescription version and then you'll only have to pay your copay, which is usually less than the OTC cost. The prescription formulation is the same as the OTC product, comes in generic, and is equally effective and safe. It's definitely worth the trip to the pharmacy because as we all know, a penny saved is a penny earned!

Cate Sibley received her doctor of pharmacy degree from Northeastern University in Boston, and is currently a community pharmacist in Charlotte, NC. Her goal behind becoming a pharmacist was to be an accessible source of information to patients so they can understand their medications as best as possible. To reach her goal, she and Nova Simpson started a website called, and by visiting, you can get a free report on how to save money on your prescription medications.

By Cate Sibley, PharmD
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Title Annotation:A Primer on ...
Author:Sibley, Cate
Publication:Pediatrics for Parents
Article Type:Report
Geographic Code:1USA
Date:Mar 1, 2010
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