Is Miralax Toxic for Children?

By Steve Hodges, M.D.

PEG 3350 is a fraught topic. Many physicians consider this laxative totally safe, while many outraged parents report that their children were harmed by it. What do I think?

I think PEG 3350 is safe for most children (I gave it to my own kids without incident) but may well negatively affect some kids. I also believe no parent should feel compelled to give PEG 3350 to their children.

Alternative osmotic laxatives — lactulose, magnesium hydroxide, magnesium citrate — work just as well and pose no safety concerns in recommended doses. I never insist parents give their children Miralax. I think it’s fine if you want to use it. And it’s fine if you don’t. (For those seeking alternatives, I discuss dosing and pros/cons in the M.O.P. Anthology.)

My larger concern with Miralax is that physicians overuse this laxative to treat encopresis (chronic poop accidents) and enuresis (bedwetting and daytime wetting).

Children spend years on the Miralax merry-go-round — doing repeated high-dose “clean-outs” and daily maintenance doses — and their symptoms persist or worsen. As I’ve written repeatedly, research demonstrates that an enema-based regimen such as the Modified O’Regan Protocol (M.O.P.) is far more effective and plenty safe.

Miralax is good at softening stool. It's not very good for dislodging the hard masses of poop that clog the rectum and are the root cause of bedwetting and daytime accidents.

READ: Getting Your Constipated Child Off the Miralax Merry-Go-Round

READ: Why Miralax Clean-Outs Often Don’t Work

But, that is not my topic for today! Back to Miralax safety.

More than 100 published articles have studied PEG 3350 in children, and none have linked it to severe or harmful side-effects, psychiatric or otherwise. These studies indicate PEG 3350 does not enter the child’s bloodstream, has no effect on the body’s balance of electrolytes, and just washes out the colon.

However, in 2009, the Drug Safety Oversight Board of the United States Food and Drug Administration published a summary of PEG side-effects reported by parents to the FDA’s Adverse Event Reporting System.

Reported side effects included seizures, tics, lethargy, rage, anxiety, aggression, tremors, and obsessive-compulsive behaviors. A small fraction of my patients and members of our private support groups have reported symptoms such as these, too. Just because no studies, to date, have found a direct association between PEG 3350 and behavioral changes doesn’t mean no such association exists.

Why might PEG 3350 cause psychiatric symptoms in children? The answer, so far, is unknown.

It’s unclear whether the reported neurobehavioral effects are caused by PEG 3350 itself, contaminants in certain brands, or something else entirely.

Neurological issues aside, one common argument against PEG 3350 is that it has not been approved by the FDA for use in children. This is true, and in light of this fact, giving PEG 3350 to a child sounds irresponsible. My own wife was distraught, for this reason, when I gave Miralax to our children.

But I don’t make much of the fact that Miralax isn’t FDA-approved for kids. Nearly 80% of hospitalized children receive medications that are not approved for children. Once the FDA approves a drug for any indicated use, physicians may legally prescribe the drug for patients in other age groups.

That’s called off-label use, and it’s common practice. PEG 3350 was approved by the FDA for adults in 1999, is available over the counter, and is already taken by children all over the world every day. So, the manufacturer has no incentive to fund the complex, lengthy, and expensive process required to petition for the drug’s approval in children.

The fact that PEG 3350 is not FDA-approved for children does not mean it is unsafe for children. Only a small number of drugs have been formally tested in children. Because PEG 3350 is actually one of them and because thousands of my patients have taken this drug without incident, I’m inclined to think it’s safe, at least for short durations.

I certainly welcome all research into the possible neurological side-effects of Miralax in children. In general, I treat Miralax like any medicine or food: If it causes problems for your child, steer clear.