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What to do if…
your infant under three months has a fever or is unusually sleepy

Produced and maintained by PanicStation.org Published: Last reviewed: Editorial policy USA guide

Short answer

A baby under three months with a rectal or forehead temporal-artery temperature of 100.4°F (38°C) or higher should go to the ER right away. Call 911 if your baby is hard to wake, cannot wake enough to feed, is limp or floppy, has blue or gray lips or tongue, is struggling to breathe or has a seizure.

Do not do these things

  • Do not wait at home to see whether a fever improves.
  • Do not delay emergency care while repeating temperature checks or trying home remedies.
  • Do not rely on touch or a forehead strip alone.
  • Do not use an ear thermometer for a baby under 6 months.
  • Do not use cold baths, ice or rubbing alcohol.
  • Do not overdress or tightly bundle your baby.
  • Do not give aspirin.
  • Do not give fever medicine before speaking with a clinician.
  • Do not give ibuprofen to a baby under 6 months unless a clinician tells you to.
  • Do not assume recent vaccines explain the fever without getting clinical advice.

What to do now

  1. Call 911 now if your baby cannot be woken enough to feed, is limp or floppy, has blue or gray lips or tongue, is struggling to breathe, has a seizure or is rapidly getting worse.
  2. Go to the ER right away if a rectal or forehead temporal-artery temperature is 100.4°F (38°C) or higher, even if your baby otherwise looks well. You can call your pediatrician while arranging care, but do not delay the trip.
  3. Check the temperature with a digital thermometer if you can do so without delaying care.
    • A rectal temperature is the most reliable measurement for an infant under three months.
    • A forehead temporal-artery thermometer can be used. A forehead strip is not reliable.
    • An underarm reading is less accurate. If an underarm reading is elevated, or you cannot get a reliable reading and your baby seems unwell, call your pediatrician immediately for direction.
    • Do not delay emergency care if your baby has warning signs.
  4. Treat unusual sleepiness as urgent even without a confirmed fever.
    • Call your pediatrician immediately if your baby is much sleepier than usual, is feeding less or is not acting normally.
    • Call 911 if your baby is difficult to awaken or cannot wake enough to feed.
  5. While arranging care, keep things simple.
    • Keep your baby lightly dressed in a comfortable room.
    • Offer a usual feed only if your baby is awake and willing. Do not force a feed.
    • Note the highest temperature, the time, how it was measured, feeding changes, wet diapers, vomiting, rash, breathing changes, recent vaccines and any medicine already given.
  6. Tell the clinician the baby’s age in weeks and give the notes from step 5.

What can wait

  • You do not need to work out the cause.
  • You do not need to try to bring the fever down before seeking care.
  • You do not need to decide which tests or treatments might be needed.
  • You do not need to pack more than is necessary to leave promptly.

Important reassurance

It is reasonable to feel alarmed by fever or unusual sleepiness in a very young infant. Prompt assessment is the appropriate next step, and clinicians expect caregivers to seek help for these signs.

Scope note

These are first steps only. A clinician may need to assess your baby and guide later decisions.

Important note

This is general information, not medical advice for a specific child. Call 911 for emergency warning signs or seek urgent clinical care if your baby is getting worse.

Additional Resources

Closely connected guides that may be useful during the same situation or its immediate aftermath.

About this guide

This guide was produced and is maintained by PanicStation.org using its published editorial process. Official and specialist sources are checked where relevant, and AI-assisted tools may be used for drafting, organisation, and consistency checks. The site operator remains responsible for publication, revision, and removal decisions.

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