Guide / Warning signs in babies: when not to wait until morning

Warning signs in babies: when not to wait until morning

Updated: September 27, 2026 · Based on: American Academy of Pediatrics

In short

Don’t wait until morning if a baby under 3 months has a fever of 38°C (100.4°F) or more, or if a child is lethargic and hard to wake, has trouble breathing or bluish lips, has a seizure, a stiff neck or a rash that does not fade when pressed. Get urgent help: go to the emergency room or call your local emergency number.

Video (23 s). Loads from YouTube when you tap play.

Urgent: ER or emergency number

Fever of 38°C (100.4°F) or more in a baby under 3 months, even with no other symptoms.
Temperature of 40.5°C (105°F) or more at any age.
Lethargy, difficulty waking, not responding to voice or touch.
Trouble breathing, wheezing, bluish lips.
Seizures, a stiff neck or a rash that does not fade when pressed.

How to check if a rash fades

Press the side of a clear glass firmly against the rash. If the spots are still clearly visible through the glass, don’t wait: this needs urgent help.

Call your doctor

Signs of dehydration: a dry diaper for more than 6 hours, crying without tears, a sunken soft spot on the head.
Persistent vomiting or diarrhea lasting more than a day in a baby.
Fever lasting more than 72 hours in a child over 6 months.

Emergency numbers

Use your local emergency number: 112 across the European Union, 999 in the UK, 911 in the US and Canada. In the UK, NHS 111 helps with urgent problems that are not life threatening.

In doubt? Better to check once too often. Temperature thresholds by age are in baby fever: when to see a doctor.

Fridge cheat sheet (PDF)

Fever thresholds by age, when to call emergency services, the glass test and space for your pediatrician’s number. One A4 page to print. Download the cheat sheet

Calm Parent

The list of warning signs and emergency info are always at hand in the app, together with the history of readings you can show the doctor. No ads, 14 days of Premium free.

Get it on Google Play

Sources

American Academy of Pediatrics
Mayo Clinic

This article is for information only and does not replace medical advice. If something worries you, contact a doctor. In an emergency, call your local emergency number.