Miralax is generally considered safe for children and is the most commonly recommended laxative for pediatric constipation. Both the North American and European societies for pediatric gastroenterology recommend polyethylene glycol 3350 (the active ingredient in Miralax) as the first-line treatment for childhood constipation. That said, Miralax is technically approved by the FDA for adults only, so pediatric use is off-label, which is why parents understandably have questions.
How Miralax Works in Kids
Miralax is an osmotic laxative, meaning it draws water into the stool as it passes through the intestines. This makes bowel movements softer and easier to pass. The compound itself is barely absorbed by the body. It passes through the digestive tract largely intact, which is a key reason pediatric specialists consider it a low-risk option. Unlike some other laxatives, it doesn’t stimulate the intestinal muscles or create dependency, and it doesn’t ferment in the colon, so it’s less likely to cause gas or bloating than fiber-based alternatives.
What Pediatric Guidelines Recommend
The joint guidelines from NASPGHAN and ESPGHAN recommend polyethylene glycol as the first-line treatment both for clearing fecal impaction and for ongoing maintenance in children with functional constipation. For impaction, the recommended approach is 1 to 1.5 grams per kilogram of body weight per day for three to six days. For daily maintenance, a typical starting dose is 0.4 grams per kilogram per day, adjusted based on how the child responds.
For context, a standard adult capful of Miralax contains 17 grams. A 44-pound (20 kg) child on a maintenance dose would start at roughly 8 grams per day, or about half a capful. Your child’s pediatrician will tailor the dose, and it’s common to increase or decrease based on stool consistency over the first week or two.
Common Side Effects
The most frequently reported side effects are mild: nausea, stomach cramps, diarrhea, and gas. These typically resolve with dose adjustment. Because Miralax works by pulling water into the stool, diarrhea usually means the dose is too high rather than indicating a harmful reaction. Reducing the amount or frequency often fixes the problem.
The Neuropsychiatric Concern
Over the past several years, some parents have reported behavioral changes in children taking Miralax, including mood swings, anxiety, and other neuropsychiatric symptoms. The FDA reviewed these reports and determined no label changes were needed.
A large-scale study comparing over 645,000 children prescribed Miralax to nearly 106,000 children on other constipation medications found reassuring results for younger kids. Children aged 6 to 11 taking Miralax were actually less likely to be diagnosed with depression, new mood swings, or new seizures compared to children on different constipation treatments. There was no statistically significant difference in anxiety or seizure risk in this age group.
The picture was slightly more mixed for older children. Among kids aged 12 to 17, Miralax users were less likely to develop new depression, but more likely to experience new anxiety, mood swings, and seizures compared to those on other medications. It’s worth noting that this age group has higher baseline rates of these conditions regardless of medication, and the study design can’t prove Miralax caused any of these outcomes. Still, it’s reasonable to pay attention to mood or behavioral changes in a teenager starting any new medication and bring them up with your pediatrician.
Trace Impurities: Ethylene Glycol
Another concern that circulates online involves trace amounts of ethylene glycol (a component of antifreeze) found in Miralax. FDA testing did confirm that small amounts of ethylene glycol exist in polyethylene glycol 3350 as a manufacturing byproduct. However, the quantities are extremely small. Based on the recommended adult dose, a 44-pound child would be exposed to about 0.3 milligrams of ethylene glycol per day. For perspective, ethylene glycol toxicity occurs at doses thousands of times higher. The FDA has not identified these trace amounts as a safety concern.
Dietary Changes to Try Alongside or Before Miralax
Many pediatricians suggest trying dietary adjustments before reaching for a laxative, or using them together for better results. Fruits like prunes, apples, and pears contain sorbitol, a natural sugar that draws water into the bowels in a similar way to Miralax. Aiming for five servings of fruits and vegetables per day provides both fiber and fluid to keep things moving. Adequate water intake is equally important.
On the other side of the equation, excess dairy can make constipation worse. Milk, cheese, and other dairy products are common culprits, especially in children with sensitivity to cow’s milk proteins. Cutting back temporarily on dairy while increasing fruit and water is a practical first step for mild constipation. Probiotics are sometimes suggested, but research supporting their use as a standalone constipation treatment in kids is limited.
Signs That Need Medical Attention
Most childhood constipation is functional, meaning there’s no underlying disease causing it. But certain signs point to something more serious. Blood in the stool, persistent fever, unexplained weight loss, severe abdominal bloating, or constipation that started in the first few months of life all warrant a visit to the pediatrician. Fecal incontinence (stool leaking into underwear) in a toilet-trained child often signals impaction rather than a behavioral issue, and it responds well to treatment once recognized.