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uk Health & medical scares newborn fever • baby under 3 months fever • infant temperature 38c • baby feels hot under 12 weeks • baby unusually sleepy • hard to wake newborn • very sleepy baby not waking • lethargic baby under 3 months • newborn not feeding and sleepy • baby floppy or limp • newborn unwell sudden • fever in young infant • baby not themselves under 3 months • infant drowsy and warm • under 90 days fever • fever after vaccinations baby • worried newborn fever • under 8 weeks very worried

What to do if…
an infant under three months has a fever or feels unusually sleepy

By PanicStation.org Reviewed under our editorial policy Last reviewed: UK guide

Short answer

Treat this as urgent. If your baby is under 3 months and has a temperature of 38°C or higher (or you strongly suspect a fever), call NHS 111 or your GP urgently—and if they will not wake up normally, are very floppy, or breathing is a struggle, call 999 or go to A&E now.

Do not do these things

  • Do not “wait it out” because the fever seems mild—under 3 months needs urgent advice.
  • Do not rely on touch alone to decide it’s safe; check a temperature if you can.
  • Do not cool them with cold baths, ice packs, or rubbing alcohol.
  • Do not overdress or tightly wrap them.
  • Do not give paracetamol to a baby under 2 months unless a clinician tells you to.
  • Do not give ibuprofen to a baby under 3 months unless a doctor has prescribed/advised it.
  • Do not give aspirin.
  • Do not drive yourself if you feel you cannot stay calm or your baby seems to be getting worse quickly—use 999.

What to do now

  1. Get to a calmer pause (30–60 seconds). Put your baby on a firm, flat surface (or hold them securely) so you can watch breathing and responsiveness.
  2. If any of these are happening, treat it as an emergency: call 999 or go to A&E now.
    • They will not wake up normally, are very floppy/limp, or are not responding in their usual way
    • Breathing looks like hard work (grunting, very fast breathing, long pauses, chest “sucking in”)
    • Skin/lips look blue, very pale, mottled, or they feel unusually cold as well as unwell
    • A spotty purple/red rash that does not fade when you press the side of a clear glass against it
    • A seizure/fit, or you are seriously alarmed by how different they seem
    • They are under 8 weeks and you are very worried
  3. Check a temperature if you can (but don’t delay emergency help if they look very unwell).
    • Use a digital thermometer in the armpit.
    • Note the number and the time you took it.
  4. If the temperature is 38°C or higher, or you strongly suspect a fever: call NHS 111 or your GP urgently.
    • Start with: “Baby under 3 months … temperature 38 or above / unusually sleepy.”
    • Follow the advice you’re given (they may send you to an urgent assessment service or A&E).
  5. If the main worry is “unusually sleepy,” treat that as urgent even without a confirmed temperature.
    • If they are too sleepy to feed normally, much harder to wake than usual, or “not themselves,” call NHS 111/GP urgently; if they won’t wake, use 999/A&E.
  6. While you’re getting help, do simple supportive steps:
    • Keep them lightly dressed (one layer more than you).
    • Offer feeds as normal; if breastfed, offer more frequently. Don’t force.
    • Note wet nappies today (fewer than usual can matter), and any vomiting/rash/breathing changes.
  7. Write down 6 quick facts (takes 1 minute) to tell the clinician:
    • Age in weeks, highest temperature and when, how alert they are,
    • Feeding amount/frequency, wet nappies today,
    • Any rash/breathing changes/vomiting,
    • Any recent vaccinations (and when),
    • Any medicines already given (name/time).
  8. Be ready to leave if asked.
    • Take the red book, a spare nappy, wipes, a blanket, and your notes.

What can wait

  • You do not need to work out the cause right now.
  • You do not need to try “cooling tricks” (sponging/cold baths/over-undressing).
  • You do not need to decide about tests or treatment—focus on urgent clinical assessment.
  • If the fever started soon after routine vaccinations, that can happen—still get urgent advice if your baby is under 3 months and you’re worried or they seem unwell.

Important reassurance

It’s normal to feel frightened when a very young baby seems hot or unusually sleepy. Acting quickly here is the right kind of caution—clinicians would rather assess early.

Scope note

These are first steps only: urgent safety checks, taking a temperature, and getting the right UK help fast.

Important note

This is general information, not a diagnosis. If your baby seems to be getting worse, is hard to wake, or is having trouble breathing, seek urgent medical help immediately.

Additional Resources

About this guide

PanicStation.org guides are written as plain-English first steps, then reviewed for clarity, jurisdiction, and source quality. If you notice an error, outdated information, unclear wording, or a broken link, please contact us.

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