Children's Medication Dosing Guide: Weight-Based Tables
In the pediatric ER, I see the consequences of dosing mistakes — the number one rule I teach every parent is this: dose by weight, not by age. Two 4-year-olds can need very different doses. Below are standard weight-based tables for the two fever/pain medicines every family should know how to use safely.
Key takeaways
- Always dose by your child's current weight — not their age.
- Match the amount to the concentration on YOUR bottle; infant and children's products come in different strengths.
- Acetaminophen: 10–15 mg/kg every 4–6 hours (max 75 mg/kg/day). Ibuprofen: 10 mg/kg every 6–8 hours, only for babies 6 months and older (max 40 mg/kg/day).
- Write down every dose and time — and check labels so you don't double-dose combination cold medicines.
Before you give any medicine
- Confirm with your pediatrician or pharmacist — these tables are educational; your child's doctor may adjust for their health history.
- Check the concentration on YOUR bottle. Infant and children's products come in different strengths — using the wrong table row is the most common dosing error.
- Use an oral syringe (marked in mL), not a kitchen spoon.
- Never give aspirin to children (Reye syndrome risk).
Acetaminophen (Tylenol): 10–15 mg/kg every 4–6 hours
Max: 75 mg/kg per day, no more than 5 doses in 24 hours. For babies under 6 months — and any child under 12 lb — ask your pediatrician for the dose.
| Weight | Dose (mg) | Liquid (160 mg / 5 mL) |
|---|---|---|
| 12–17 lb (5.5–8 kg) | 80 mg | 2.5 mL |
| 18–23 lb (8–10.5 kg) | 120 mg | 3.75 mL |
| 24–35 lb (11–16 kg) | 160 mg | 5 mL |
| 36–47 lb (16.5–21 kg) | 240 mg | 7.5 mL |
| 48–59 lb (22–27 kg) | 320 mg | 10 mL |
| 60–71 lb (27.5–32 kg) | 400 mg | 12.5 mL |
| 72–95 lb (33–43 kg) | 480 mg | 15 mL |
Ibuprofen (Motrin / Advil): 10 mg/kg every 6–8 hours
Only for babies 6 months and older. Max: 40 mg/kg per day. Give with food or milk if it upsets the stomach. Avoid if your child is dehydrated or has kidney problems — ask your pediatrician.
| Weight | Dose (mg) | Liquid (100 mg / 5 mL) |
|---|---|---|
| 12–17 lb (5.5–8 kg) | 50 mg | 2.5 mL |
| 18–23 lb (8–10.5 kg) | 75 mg | 3.75 mL |
| 24–35 lb (11–16 kg) | 100 mg | 5 mL |
| 36–47 lb (16.5–21 kg) | 150 mg | 7.5 mL |
| 48–59 lb (22–27 kg) | 200 mg | 10 mL |
| 60–71 lb (27.5–32 kg) | 250 mg | 12.5 mL |
| 72–95 lb (33–43 kg) | 320 mg | 16 mL |
Concentration warning: infant ibuprofen drops (50 mg / 1.25 mL) are three times stronger per mL than children's ibuprofen (100 mg / 5 mL). Always match the table to your bottle's label.
The 7 safety rules I teach every parent
- Weight, not age — always dose by your child's current weight.
- Write down every dose and time — especially at night and when caregivers share duties.
- One medicine at a time, knowingly — many multi-symptom cold products already contain acetaminophen. Check labels to avoid double-dosing.
- Do not alternate Tylenol and Motrin on your own — ask your pediatrician first; alternating invites errors.
- Measure with a syringe — kitchen spoons are wildly inaccurate.
- Recheck weight-based dose as they grow — the dose that was right 6 months ago may be too small now.
- Store all medicines up high and locked — dosing safety starts with storage safety (see poisoning prevention).
Related reading: fever in children, the right way to dose Tylenol and Motrin (blog).
Sources
This guide was reviewed against guidance from:
Frequently asked questions
Should I dose by age or weight?
Always by weight. Age-based dosing on the box is a rough estimate — two children the same age can need very different doses. Weigh your child and use the table.
Can I give ibuprofen to my 4-month-old?
No — ibuprofen is only for babies 6 months and older. For younger infants, ask your pediatrician about acetaminophen dosing.
What is the difference between infant and children's ibuprofen?
Concentration: infant drops (50 mg/1.25 mL) are three times stronger per mL than children's liquid (100 mg/5 mL). Always check your bottle's label and use the matching amount.
Can I alternate Tylenol and Motrin?
Only if your pediatrician recommends it. Alternating schedules are a common source of dosing errors — if you do it, write down every dose and time.
Why can't children take aspirin?
Aspirin in children is linked to Reye syndrome, a rare but serious illness affecting the brain and liver. Use acetaminophen or ibuprofen instead.
My child's cold medicine already has acetaminophen. Can I add Tylenol?
No — that would double-dose. Many multi-symptom products contain acetaminophen; always read the full label before adding another medicine.
Reviewed by Ali Ozcan, MD, MBA
Board-certified pediatric emergency medicine physician and creator of ER4Kids. This guide reflects the same trusted, evidence-based guidance Dr. Ozcan provides to families in the emergency department.
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