Miralax Dilemma: As Common Laxative Studied, Parents Ask, 'Is It Safe?'

By Ricki Morell

If you, like millions of parents, routinely give your child Miralax for constipation, recent reports that the Food and Drug Administration is studying a possible link between the common laxative and neuropsychiatric problems probably sounded scary.

After years of complaints from activists, two Children’s Hospital of Philadelphia researchers are now leading an FDA study of the ingredient — polyethylene glycol 3350, or PEG 3350 — to see how it affects children.

“We’re pleased that they’re going to be looking at behavior changes because that’s never been done before,” said Carol Chittenden, co-director of The Empire State Consumer Project, a nonprofit consumer group in Rochester, New York, that pushed the FDA to embark on the study. “Parents are feeling anxious but also validated because they’ve been telling their doctors for years about these symptoms.”

Just because the FDA is doing a study, doesn’t make it dangerous.

Dr. Samuel Nurko

Miralax is sold over the counter as an adult laxative, but pediatricians and gastroenterologists routinely prescribe it to infants, toddlers and older children. And they often prescribe it for long-term daily use for chronic constipation, even though the label says it should be used for no more than seven days “unless advised by your doctor.”

Dr. Samuel Nurko, director of the Center for Motility and Functional and Gastrointestinal Disorders at Boston Children’s Hospital, said parents have little reason to worry. Dr. Nurko, who was involved in previous studies of Miralax, some partially funded by the drug company that used to own Miralax, argues that the drug isn’t approved for children because of the technicalities surrounding the FDA study process. He believes Miralax is safe for children.

“Just because the FDA is doing a study, doesn’t make it dangerous,” Dr. Nurko said. “From my perspective, the risk of not treating constipation is worse. Do you think the FDA would leave it on the market if it were dangerous? I think it’s an overreaction but I’m glad that they are studying it.”

About 5 percent of children suffer from constipation, according to the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition, which has guidelines for long-term use of Miralax among other constipation treatments.

FDA spokesperson Andrea Fischer said in an email that the agency is funding the $325,000 study to explore pediatric safety concerns even though “the FDA has not determined that there is enough data to warrant additional warnings regarding these products, or to issue specific warnings about pediatric use of the drugs at this time.”

The FDA first tested Miralax in 2008 and found small amounts of ethylene glycol and diethylene glycol, toxic ingredients also found in antifreeze. In subsequent tests in 2013, it found no detectable levels of those ingredients.

Chittenden says any hint that PEG can lead to side effects known to be associated with ethylene glycol or diethylene glycol toxicity is disturbing. According to a 2009 FDA drug oversight report, neuropsychiatric side effects “may include seizures, tremors, tics, headache, anxiety, lethargy, sedation, aggression, rages, obsessive-compulsive behaviors including repetitive chewing and sucking, paranoia and mood swings.”

Diethylene glycol toxicity can also cause “metabolic acidosis,” or too much acid in the blood, which, in severe cases, can lead to shock or death.

But Fischer emphasized that the link between these side effects and Miralax is so far unproven.

“There is insufficient data to demonstrate a link between PEG 3350 and serious neuropsychiatric issues in children,” she said in the email. “And although routine testing of Miralax in 2008 showed trace amounts of EG and DEG [ethylene glycol and diethylene glycol] in the product, the amounts were so low, they complied with internationally recognized safety standards, and were not present in subsequent testing.”

The purpose of the Philadelphia study is to understand better the extent of the absorption of ethylene glycol and diethylene glycol in children, to see if there is evidence of toxins in their blood and to find out if it is linked to psychiatric problems. Researchers will recruit children with chronic constipation who are already taking a laxative that contains PEG3350.

In a statement, Bayer Corporation, the company that acquired Miralax last year when it bought Merck's consumer care business, emphasized that Miralax is intended for adults on a short-term basis. But it also said that it “always welcomes additional research to add to the body of science surrounding our products.”

The big question for parents: Should you continue to give your child Miralax? Are there safer alternatives?

A Yahoo group is devoted to chronicling the adverse effects of Miralax and the best natural alternatives. No simple solution emerges but recommendations include probiotics, more liquids, fruits and vegetables and less dairy.

If your doctor prescribes Miralax, have a serious discussion and ask for natural solutions first.

Carol Chittenden

Adding more fiber to the diet is surprisingly controversial because some studies show that a high-fiber diet may actually exacerbate constipation by decreasing intestinal flora and adding bulk to the stool.

Chittenden recommends asking your child’s pediatrician before you do anything. “If your doctor prescribes Miralax, have a serious discussion and ask for natural solutions first,” she said.

Dr. Nurko said Miralax is still his first choice for children with chronic constipation because it works and it’s easy to take. But he makes sure to tell families about the FDA concerns and provides alternatives if they don’t feel comfortable using Miralax.

Lactulose and Milk of Magnesia are his favored alternatives. Some research shows probiotics work, he said, and he agreed that adding fiber to the diet is ineffective. His primary concern, he says, is that children suffering from constipation will go untreated more than that they would be harmed by Miralax.

“Ineffective treatment of constipation changes the quality of life for children,” he says, “and that’s the part that all of us are very worried about.”

Parents, thoughts? Experiences worth sharing?

Ricki Morell is a freelance journalist who has written for The New York Times and The Boston Globe.