# Fever in babies: when to call the pediatrician

> Fever in babies and toddlers: the under-3-months rule and when to call the pediatrician

Illness & fever · Reviewed 2026-10-19 against the sources below · https://livia.baby/learn/fever

- How the child looks and acts matters more than the number on the thermometer.
- Children with immune problems, heart problems, or on steroids need a call sooner.

## When to call
- Under 3 months (12 weeks): a temperature of 100.4°F (38.0°C) or higher means the baby should be seen right away.
- Call the pediatrician right away when a fever comes with: looking very ill, unusually drowsy or very fussy; a stiff neck; trouble breathing; an unexplained rash; repeated vomiting or diarrhea; a seizure; having been somewhere very hot, like an overheated car.
- Also call when a temperature rises above 104°F (40°C) repeatedly, when the child still acts sick after the fever comes down, or seems to be getting worse.
- How long: call if a fever lasts more than 24 hours in a child under 2, or more than 3 days in a child 2 or older.

## In Livia

Log any medicine given as a record, and keep logging feeds and diapers: how long the fever has gone on and how much she's drinking are what the doctor will ask.

## Sources

- [AAP / HealthyChildren.org](https://www.healthychildren.org/English/health-issues/conditions/fever/Pages/When-to-Call-the-Pediatrician.aspx)
- [AAP / HealthyChildren.org](https://www.healthychildren.org/English/health-issues/conditions/fever/Pages/Fever-Without-Fear.aspx)

_Education from the sources listed, not medical advice. If you're worried about your child, call your pediatrician; in an emergency, call 911._