Fever Medicine Cross-Dosing Schedule Calculator

Overview

This fever medicine cross-dosing schedule calculator takes the drug and time of your child's last dose and works out when the same medicine can be given again, plus when a different medicine can be used for cross-dosing. Under Korea's MFDS approved labeling, acetaminophen (Tylenol) is dosed every 4–6 hours up to 5 times a day, while ibuprofen-family medicines (Advil, Mapap, dexibuprofen) are dosed every 6–8 hours up to 4 times a day. If you want to switch to a different active ingredient because the fever hasn't come down, at least 2 hours — 3 or more recommended — should pass first. Enter which dose of the day this is for the same drug, and the calculator also flags whether you've hit the daily maximum.

Formula

Next same-drug dose time = last dose time + minimum interval
(Acetaminophen 4–6 h / Ibuprofen family 6–8 h)

Cross-dosing (different drug) time = last dose time + 2–3 h
(minimum 2 h, 3+ h recommended per Korean Pediatric Society guidance)

Example: acetaminophen given at 2:00 PM → same drug again between 6:00–8:00 PM; cross-dosing with ibuprofen-family from 5:00 PM

How to Use

1. 1Select the drug given last (acetaminophen or ibuprofen family).
2. 2Enter the time of the last dose.
3. 3Enter which dose of the day this is for that drug (including this one).
4. 4Check when the same drug can be repeated and when a different drug can be cross-dosed.

Examples

Background

Korea's MFDS approved labeling limits acetaminophen to every 4–6 hours (max 5 doses/day) and ibuprofen-family medicines to every 6–8 hours (max 4 doses/day). Because the two act through different mechanisms, cross-dosing between them is possible, but the Korean Pediatric Society still recommends leaving at least 2–3 hours between a dose of one and a dose of the other — a different active ingredient does not mean it's safe to give immediately. Cross-dosing is meant as a backup when a single medicine isn't controlling the fever well enough, not a routine way to alternate two drugs. The actual per-dose amount (mg/mL) depends on body weight, so check the separate Child Fever Medicine Dose Calculator for that.

Tips

• ✔Treat cross-dosing as a backup option, only when one medicine alone isn't controlling the fever.
• ✔Note down the drug and time of each dose so you don't lose track of when the next one is due.
• ✔If you've reached the daily maximum (5 for acetaminophen, 4 for ibuprofen family), see a doctor instead of giving more.
• ✔For infants under 6 months, or children with underlying conditions or dehydration, check with a doctor before cross-dosing.

FAQ