Constipation · Over the counter
MiraLAX (polyethylene glycol) dosage for children
Also sold as PEG 3350, GlycoLax, generic ClearLax
The MiraLAX package is labeled for ages 17 and up, so children should take it on a doctor’s advice. Pediatric guidelines use 0.2 to 0.8 grams per kg of body weight per day for daily treatment. A full capful is 17 g, the adult dose, which is also a sensible daily ceiling for home use unless the doctor says otherwise. Stir each dose into 4 to 8 oz of a drink.
Source: ESPGHAN and NASPGHAN · Hospital Pharmacy · Bayer HealthCare
MiraLAX dose calculator
MiraLAX daily dose by weight
| Weight | Guideline range0.2-0.8 g/kg/day | Common starting dose0.4 g/kg/day |
|---|---|---|
| 6 kg 13 lb | 1.2-4.8 g | 2.4 gabout ¼ capful |
| 8 kg 18 lb | 1.6-6.4 g | 3.2 gabout ¼ capful |
| 10 kg 22 lb | 2-8 g | 4 gabout ¼ capful |
| 12 kg 26 lb | 2.4-9.6 g | 4.8 gabout ¼ capful |
| 15 kg 33 lb | 3-12 g | 6 gabout ¼ capful |
| 18 kg 40 lb | 3.6-14.4 g | 7.2 gabout ½ capful |
| 20 kg 44 lb | 4-16 g | 8 gabout ½ capful |
| 25 kg 55 lb | 5-17 g | 10 gabout ½ capful |
| 30 kg 66 lb | 6-17 g | 12 gabout ¾ capful |
| 40 kg 88 lb | 8-17 g | 16 g1 capful |
- Under 6 months: don’t give MiraLAX unless your baby’s doctor tells you to.
Range: ESPGHAN and NASPGHAN, as summarized in Hospital Pharmacy. 17 g capful: Manufacturer.
A doctor-guided medicine for children
Polyethylene glycol 3350 is the first choice for childhood constipation in the ESPGHAN/NASPGHAN guideline, and it’s widely used from infancy. Because the label is for adults, your child’s doctor should set the starting dose and adjust it. The calculator shows the guideline range so you can follow that plan in grams and capfuls.
Clean-outs for hard, stuck stool (fecal impaction) use much higher doses for a few days. Do a clean-out only with a doctor’s specific instructions. It isn’t covered here.
How to measure and mix it
- The cap has a fill line at 17 g. Half a capful is about 8.5 g, and a quarter is about 4.25 g. A kitchen scale that reads grams is more accurate for small doses.
- Stir into 4 to 8 oz of water, juice, or milk and let it dissolve for a few minutes. It has no taste once dissolved.
- Give it once a day, at the same time each day.
- Adjust slowly, as your doctor directs, until your child has a soft stool every day that’s easy to pass.
When constipation needs a doctor
- Your baby is under 6 months, or is under 1 year and constipated.
- Stomach pain, vomiting, a swollen belly, or blood in the stool.
- Watery diarrhea after starting MiraLAX (the dose may be too high).
- Constipation doesn’t improve after 1 to 2 weeks.
Common questions
How much MiraLAX can I give my 2-year-old?
Ask your child’s doctor for a starting dose. A typical 2-year-old weighs about 12 kg (26 lb), which works out to about 5 g a day at the common starting dose of 0.4 g/kg, a bit less than a third of a capful.
Is MiraLAX habit-forming?
It isn’t addictive, and doctors often prescribe it daily for months while a child’s bowels recover. Stop or change it only with your doctor.
How long does MiraLAX take to work?
Usually 1 to 3 days.
Sources
- Evaluation and Treatment of Functional Constipation in Infants and Children (Tabbers et al.). ESPGHAN and NASPGHAN, J Pediatr Gastroenterol Nutr 2014;58(2):258-274. Checked 2026-09-18.
- Evaluation of Polyethylene Glycol Dosing for Functional Constipation in Children. Hospital Pharmacy, 2024 (PMC11497520). Checked 2026-09-18.
- MiraLAX (polyethylene glycol 3350): Drug Facts. Bayer HealthCare, label via DailyMed. Checked 2026-09-25.