Infant Tylenol & Motrin Dosage Calculator
Calculate safe dosage for infant acetaminophen (Tylenol) and ibuprofen (Motrin) based on weight
IMPORTANT MEDICAL DISCLAIMER
Always consult your pediatrician before giving any medication to your infant. This calculator is for reference only and does not replace professional medical advice.
WARNING: Do NOT give acetaminophen to infants under 2 months old without doctor approval.
WARNING: Do NOT give ibuprofen to infants under 6 months old. It can cause serious side effects.
Enter Infant Information
IMPORTANT MEDICAL DISCLAIMER
- Do NOT exceed more than 5 doses in 24 hours for acetaminophen or 4 doses in 24 hours for ibuprofen unless directed by a doctor.
- This calculator is based on standard dosing guidelines. Individual needs may vary. Consult your healthcare provider for personalized advice.
Paediatric dosing of paracetamol and ibuprofen is by weight, not by age, and that single rule prevents most of the errors that occur. Age bands printed on packaging are a fallback for when weight is unknown; they assume an average-sized child and will under-dose a large one and over-dose a small one. This page explains how the dosing works and where the hazards are. It does not replace the dosing instruction from your clinician or the product label.
The formula
Paracetamol (acetaminophen): 10 to 15 mg per kg per dose, every 4 to 6 hours, maximum 4 doses in 24 hours
Ibuprofen: 5 to 10 mg per kg per dose, every 6 to 8 hours, maximum 4 doses in 24 hours
Volume (mL) = dose (mg) / concentration (mg per mL)- Concentration must be read from the specific bottle, because several strengths exist for both drugs
- Ibuprofen is not given to infants under 6 months without medical advice
Standard weight-based paediatric dosing ranges. Always follow the specific instruction on the product supplied and any advice from your clinician.
Why concentration is the dangerous variable
The most consequential error in paediatric liquid dosing is not the milligram calculation, it is the conversion to millilitres. Both paracetamol and ibuprofen are sold in more than one concentration, and infant drops are more concentrated than children suspension. Measuring the correct millilitre volume for the wrong bottle can deliver several times the intended dose.
The practical rules that follow are simple and worth stating explicitly. Read the concentration on the bottle in front of you every time. Use only the syringe or cup supplied with that bottle, since devices are calibrated to their product. Never use a kitchen spoon, which varies by a factor of two or more.
- Check the concentration on every new bottle, including a replacement of the same brand, because formulations change.
- Never give two products containing the same active ingredient. Many combination cold remedies contain paracetamol, and doubling up is a common cause of overdose.
Dosing intervals and daily limits
Both drugs have a maximum number of doses in 24 hours, and exceeding it is the mechanism of most paediatric paracetamol toxicity, which is usually cumulative rather than a single large overdose. Keeping a written record of the time of each dose is more reliable than memory, particularly when more than one adult is caring for the child overnight.
- Aspirin is not given to children or teenagers because of the association with Reye syndrome, except on specialist advice.
- Alternating the two drugs is sometimes advised by clinicians but increases the risk of dosing error, and is not needed for most fevers.
| Drug | Dose | Interval | Max in 24 h | Minimum age |
|---|---|---|---|---|
| Paracetamol (acetaminophen) | 10 to 15 mg/kg | Every 4 to 6 hours | 4 doses | Follow product label; often 2 to 3 months |
| Ibuprofen | 5 to 10 mg/kg | Every 6 to 8 hours | 4 doses | Not under 6 months without medical advice |
When medicine is not the answer
Fever itself is a normal immune response and does not require treatment simply because a thermometer reads high. The reason to treat is discomfort. A child with a temperature of 39C who is drinking, alert and playing needs less intervention than a miserable child at 38.2C.
What matters far more than the number is how the child looks and behaves, and there are specific situations where any fever needs assessment rather than treatment at home.
- Any fever in an infant under 3 months needs same-day medical assessment.
- Fever with a rash that does not fade under pressure, a stiff neck, or unusual drowsiness needs emergency assessment.
- Difficulty breathing, persistent vomiting, signs of dehydration such as fewer wet nappies, or a fever lasting more than about five days need review.
- Ibuprofen is generally avoided in dehydration, in chickenpox, and in children with kidney problems or asthma triggered by NSAIDs.
Limitations
- This page explains general weight-based ranges. The dosing instruction on the product you have, and any advice from your clinician, take precedence over anything here.
- Concentrations differ between products and between countries. A calculated millilitre volume is valid only for the specific concentration it was calculated from.
- Weight-based dosing requires a current weight. Children grow quickly and an out-of-date weight under-doses.
- Preterm infants, neonates, and children with liver or kidney impairment require individualised dosing that these ranges do not cover.
- Nothing here applies to prescription medicines, combination products, or any drug other than the two named.
- If you think a child has received too much of either drug, contact poison control or emergency services immediately; paracetamol overdose can be serious even when the child initially appears well.
Frequently asked questions
Should I dose by weight or age?
By weight whenever the weight is known. Age bands on packaging assume an average-sized child and will under-dose a large child and over-dose a small one. Weight-based dosing is what clinicians use.
How much paracetamol can I give my baby?
The general range is 10 to 15 mg per kilogram per dose, every 4 to 6 hours, with no more than four doses in 24 hours. Convert to millilitres using the concentration on your specific bottle, and follow the product label and your clinician advice.
Can I give ibuprofen to a young infant?
Not under 6 months without medical advice. It is also generally avoided in dehydration, in chickenpox, and in children with kidney problems or NSAID-triggered asthma.
Why does the concentration on the bottle matter so much?
Because both drugs come in more than one strength, and infant drops are more concentrated than children suspension. Measuring the right volume for the wrong concentration can deliver several times the intended dose. Read the bottle every time and use only its supplied syringe.
Do I need to treat every fever?
No. Fever is a normal immune response, and the reason to treat is discomfort rather than the number. How the child looks and behaves matters more. Any fever in an infant under 3 months, or fever with a non-blanching rash, stiff neck or unusual drowsiness, needs urgent assessment.