How to Use the Painkiller Max Dose Calculator
When pain or fever won't let up, it's tempting to take more than the recommended amount. But both acetaminophen and ibuprofen have real daily maximums, and exceeding them raises the risk of liver damage or gastrointestinal bleeding. This calculator uses FDA OTC drug facts label ranges to estimate the max single dose, max daily dose, and recommended dosing interval based on who's taking it, the drug type, and weight.
For adults, acetaminophen labels typically allow 650mg per dose (extra strength) every 4–6 hours, with daily maximums that range from 3,000mg to 4,000mg depending on the specific product — always check your label. Ibuprofen OTC labels cap out at 400mg per dose and 1,200mg per day, taken every 6–8 hours. For children, dosing is calculated at roughly 10–15mg/kg per dose for acetaminophen and 5–10mg/kg per dose for ibuprofen, capped so it never exceeds the adult maximum.
These are general guidelines only — actual limits can differ if your child has a liver or kidney condition, or if you're taking other medications. If pain or fever doesn't improve or worsens even within the max dose, don't increase it on your own; see a doctor instead. Always defer to your specific product's label and a pharmacist's or doctor's advice.
Frequently Asked Questions
They work through different mechanisms and are commonly alternated or combined, but each has its own maximum you must respect separately. Always check whether a combination product already contains both, so you don't accidentally double up.
Children metabolize medication very differently depending on body weight, so age alone isn't a reliable way to set a safe dose. Dosing is calculated per kilogram of body weight, with a cap so the result never exceeds the adult maximum.
If pain or fever lasts more than a few days or gets worse even while staying within the max dose, don't increase the dose on your own — see a doctor. This calculator provides general guidance only, and actual limits can vary by individual health condition.