Polyethylene glycol 3350, also termed PEG 3350 (Dulcolax Balance, MiraLAX), is used to alleviate constipation. It is also the active ingredient in some more concentrated preparations used to cleanse the bowel before colonoscopy so that polyps can be clearly visualized.

Because polyethylene glycol is not absorbed, it stays in the digestive tract and attracts liquid, making the stool softer and bulkier. Over-the-counter products containing polyethylene glycol are designed to be used by adults for short-term relief of constipation and generally produce results within two to four days.

Although it is labeled for occasional use only and for not more than seven consecutive days, the manufacturer of MiraLAX has funded a study showing that it can be used safely for as long as a year (Alimentary Pharmacology & Therapeutics, Mar. 15, 2007).

Questions about Children

Chronic constipation in children can be difficult to treat. A study comparing polyethylene glycol and electrolytes to a complex fiber preparation for this condition found that the youngsters preferred the polyethylene glycol product and that both worked equally well, relieving constipation for more than three-fourths of the children in the study (Journal of Pediatrics, Oct., 2012).  It would be advisable to check with the pediatrician before giving a child a polyethylene glycol-based laxative, however.

Some disturbing questions have been raised regarding the safety of PEG 3350 for children. The FDA has requested a study to determine whether young children may absorb some of the compound, unlike healthy adults who do not. The agency has also found traces of two toxic compounds, ethylene glycol and diethylene glycol, in prior batches of MiraLAX. Although it has stated that the levels of these antifreeze components were too low to be troubling, some parents worry about whether such impurities might have negative consequences for children who take the laxative daily for long periods of time. In particular, concern has been raised that tics and obsessive compulsive disorder might be more common in children exposed to PEG 3350 over many months. There are not enough data to determine whether this worry is well-founded.

Side Effects:

Side effects of polyethylene glycol include diarrhea, flatulence, bloating, stomachache and nausea.

Polyethylene glycol should not be used in the case of possible bowel obstruction. People with kidney disease should use this laxative only under medical supervision.

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  1. EL

    About three weeks ago I had an impacted colon, and was treated at a hospital ER. I received excellent care and it was all over within 40 minutes. The size of the stool was unbelievable, I could not believe that I was walking around with it in my colon!
    I was given a prescription for Polyethylene Glycol powder, to take a cap-full once a day, plus a stool softener. For a 90 year old senior with constipation 3 to 4 BMs in a week and a half was incredible. Unfortunately the stools turned to 85% liquid. I stopped taking the Glycol powder and just used the stool softener. After another week or so I decided to resume the Glycol, but only three times a week, and the same for stool softener. I will see what the future brings!

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