Fever in Children: When to Worry & When to Give Medicine

Evidence-based guide for parents on managing pediatric fever

What Temperature is a Fever in Children?

Many parents ask "what temperature is considered a fever?" The answer depends on how you measure it:

MethodNormal RangeFever
Rectal (most accurate for babies)97.9-100.4°F≥100.4°F (38°C)
Oral (children 4+)95.9-99.5°F≥99.5°F (37.5°C)
Armpit/Axillary94.5-99.1°F≥99°F (37.2°C)
Ear/Tympanic96.4-100.4°F≥100.4°F (38°C)
Forehead/Temporal97.4-99.4°F≥100.4°F (38°C)
Key point: For babies under 3 months, always use rectal temperature. A fever of 100.4°F or higher in a newborn requires immediate medical attention.

When to Call the Doctor or Go to the ER

Go to the Emergency Room immediately if your child has:
  • Baby under 3 months with fever ≥100.4°F (any fever in newborn)
  • Difficulty breathing or rapid breathing
  • Purple spots or rash that doesn't fade when pressed
  • Stiff neck or severe headache
  • Seizure or convulsion
  • Very difficult to wake or extremely lethargic
  • Blue lips or fingernails
Call your pediatrician if:
  • Fever over 104°F (40°C) at any age
  • Fever lasting more than 3 days (72 hours)
  • Child refuses to drink or shows signs of dehydration
  • Crying inconsolably or extremely irritable
  • Fever returns after being gone for 24+ hours
  • Child has underlying health conditions

When to Give Tylenol or Motrin for Fever

The goal is to treat discomfort, not the number on the thermometer. A fever itself is not dangerous—it's the body fighting infection.

Give fever medicine (Tylenol or Motrin) if your child:

Important: Motrin (ibuprofen) is NOT safe for babies under 6 months. Use only Tylenol (acetaminophen) for younger infants.

Frequently Asked Questions About Pediatric Fever

Can I alternate Tylenol and Motrin for my child's fever?

Yes, but only if necessary. Learn how to safely alternate Tylenol and Motrin. Give one medication, wait 4-6 hours, then the other if the fever returns. Routine alternating is not recommended as it increases the risk of dosing errors.

Should I wake my child to give fever medicine?

No. Sleep is healing. Let your child rest unless they seem very ill or you're concerned about their condition.

Does teething cause fever in babies?

Teething may cause a slight temperature increase (up to 99°F) but does not cause true fever. If your baby has a temperature over 100.4°F, look for another cause such as an infection.

How long does a fever typically last?

Most viral fevers last 2-3 days. If fever persists beyond 72 hours or your child isn't improving, contact your pediatrician.

Calculate the Exact Tylenol or Motrin Dose

Enter your child's weight for accurate, safe dosing in mg and ml

Go to Dose Calculator

Related Articles:

→ Tylenol vs Motrin: Which is Better for Fever? → Can You Alternate Tylenol and Motrin? → Child Vomited Medicine: What to Do