Miralax Pediatric Dosing Chart: What Most Parents Get Wrong

Honestly, if you're staring at a capful of white powder and wondering if you're about to give your toddler too much—or not enough—you aren't alone. Dealing with a kid who can't poop is a special kind of stress. You've got the belly aches, the "withholding" dance, and that vague sense of dread every time they head toward the bathroom.

Basically, Miralax (or its generic name, polyethylene glycol 3350) has become the gold standard for pediatricians. It’s an osmotic laxative. That just means it draws water into the colon to soften things up. It doesn't "force" the muscles to move, which is why doctors generally prefer it over stimulant laxatives.

But here’s the kicker: the bottle in your cabinet is labeled for adults. If you look for a miralax pediatric dosing chart on the back of the bottle, you won't find one. It usually says "consult a physician" for anyone under 17. That's not very helpful when it’s 7:00 PM and your kid is crying.

The Reality of the Miralax Pediatric Dosing Chart

Most parents assume there's one "magic number" based on age. That's not really how it works. Pediatricians typically dose by weight or by the specific goal—are you just trying to keep things moving (maintenance), or are you dealing with a "blockage" situation (a clean-out)?

The standard adult dose is 17 grams, which is one full capful. For kids, we're usually talking about fractions of that.

General Maintenance Dosing (Daily Use)

For daily maintenance, the goal is one or two soft, "mushy" stools. If it looks like a banana, you're winning. If it looks like rabbit pellets, you need more. If it’s liquid, you’ve gone too far.

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• Infants (6 to 12 months): Usually not recommended unless a doctor is supervising. If they do, it's often a tiny amount, like 1/4 capful (approx. 4 grams) mixed into 2–4 ounces of water or prune juice.
• Toddlers (1 to 3 years): A common starting point is 1/4 to 1/2 capful daily.
• Preschoolers (4 to 5 years): Often around 1/2 capful (8.5 grams).
• School-Aged Kids (6 to 12 years): Typically 1/2 to 3/4 capful.
• Teens (13+ years): Usually the full adult dose of 1 capful (17 grams).

Medical groups like NASPGHAN (North American Society for Pediatric Gastroenterology, Hepatology and Nutrition) suggest a weight-based maintenance dose of roughly 0.4 to 1.0 gram per kilogram of body weight.

To make it simple: if your child weighs 44 lbs (20 kg), a standard maintenance dose might be around 8 to 17 grams. That’s roughly half a cap to a full cap daily.

Why the "Clean-Out" Is a Different Beast

Sometimes, a child is so "backed up" that maintenance dosing won't cut it. This is where you see those scary-looking charts with high doses. This is the "disimpaction" phase.

Doctors at Children’s Hospital of Orange County (CHOC) and Nationwide Children’s often use a much more aggressive miralax pediatric dosing chart for a 2-day or 3-day "clean-out." We're talking 1 to 1.5 grams per kilogram per day.

For a child between 34 and 44 pounds, a clean-out might involve 1/2 capful taken three times a day for two days. For a bigger kid, say 60 pounds, it could be a full capful three times a day.

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The goal here is "clear" or very liquid output. It’s basically a colonoscopy prep for kids. Don't ever do this without a doctor's green light, because it can cause dehydration if you aren't careful with fluids.

The Fluid Rule: You Can't Skip This

This is the mistake I see most often. Miralax is a sponge. It needs water to work. If you give the powder but your kid doesn't drink enough liquid, it’s like putting a dry sponge in a pipe—it's not going to help the flow.

You've got to mix each capful with at least 4 to 8 ounces of liquid. If you're only giving half a cap, you still want at least 4 ounces. Water is best, but juice (apple, pear, or prune) works too because those juices have natural sugars that help pull water into the gut anyway.

Common Myths and "The Miralax Scare"

You might have seen some scary headlines or Facebook posts about Miralax causing "behavioral issues" or "neuropsychiatric symptoms." It’s a polarizing topic.

The FDA actually commissioned a study at Children’s Hospital of Philadelphia (CHOP) to look into this because parents were reporting things like tics, anxiety, and aggression. Technically, Miralax is Polyethylene Glycol (PEG) 3350. There were concerns about trace amounts of ethylene glycol or diethylene glycol (basically antifreeze components) being present.

However, the prevailing medical consensus in 2026 remains that for the vast majority of kids, PEG 3350 is safe because it isn't absorbed into the bloodstream. It stays in the "lumen" (the inside) of the bowel and passes right through. Still, if you notice your kid acting weird after starting it, trust your gut. Talk to your pediatrician about alternatives like lactulose or milk of magnesia.

"Will my kid get addicted to it?"

Nope. This is a big one. People worry about "lazy bowel syndrome." Because Miralax is an osmotic (water-based) laxative and not a stimulant, it doesn't mess with the nerves or muscles of the colon in a way that causes dependency.

In fact, the biggest mistake parents make is stopping the Miralax too soon. If you stop the second they have one good poop, they’ll probably get backed up again, get scared of the pain, and start "withholding" all over again. Most GIs recommend staying on a maintenance dose for 2 to 6 months to let the stretched-out colon shrink back to its normal size and "relearn" how to feel the urge to go.

Actionable Steps for Parents

1. Consult first: Call your pediatrician for a specific number based on your child's current weight. Don't guess.
2. Measure accurately: Use the cap. A full cap to the "fill line" is 17 grams. Halfway to that line is 8.5 grams.
3. Mix it well: Stir it until it’s clear. If it's gritty, they’ll hate it. If your kid is picky, mix it into a smoothie or even yogurt (though liquid is better for hydration).
4. The "S" Rule: Look for stools that are Soft, Smooth, and Sausage-shaped. If they are, you’ve found the right dose.
5. Be Patient: Miralax usually takes 24 to 72 hours to work. It is not an "emergency" fix like a suppository. It's a slow-and-steady wins the race situation.
6. Wean slowly: When it's time to stop, don't go cold turkey. Drop the dose by a teaspoon every few weeks.

Constipation is a marathon, not a sprint. If you find the right spot on the miralax pediatric dosing chart and stay consistent, you'll eventually get past the "poop wars." Just keep that water bottle filled.