Baby fever: when to call 111 or seek medical help

A baby under 3 months with a temperature of 38°C or higher needs urgent professional assessment now. A baby aged 3 to 6 months with 39°C or higher also needs urgent assessment. These readings tell you when to seek help, not what is causing the fever. Your baby's age, breathing, alertness, colour, feeding, hydration, changed behaviour and your concern all matter.

The service to contact depends on where you are. In England, use NHS 111 or your GP surgery for these young-baby thresholds; in Wales, use NHS 111 Wales or your GP surgery. In Scotland, NHS Inform places a temperature of 38°C or above in a baby under 3 months in its 999 section, subject to its specific post-vaccination advice; for other fever concerns, contact your GP and phone 111 when the GP is closed. In Northern Ireland, use your GP or local GP out-of-hours service rather than NHS 111. Call 999 anywhere in the UK for life-threatening signs.

A temperature cannot reveal the cause or prove how ill or safe your baby is. A lower reading, the absence of one warning sign or a change after medicine does not rule out serious illness. This is general information, not a diagnosis or a substitute for assessment by a qualified healthcare professional. Seek help again if your baby worsens or you remain worried.

How to take a baby's temperature

What counts as a high temperature in a baby

A high temperature is 38°C or more. This is a useful definition for measuring and reporting a fever, but it does not identify the cause or show how serious an illness is.

For babies older than 6 months, the height of the temperature alone should not be used to judge how serious the illness is. At any age, how your baby is breathing, waking, feeding and behaving can matter more than one number.

How to use a digital thermometer in the armpit

Use a digital thermometer at the top of your baby's armpit and follow the instructions supplied with it.

• Place the thermometer inside the top of the armpit, against the skin.
• Gently hold your baby's arm against their body while the thermometer takes the reading.
• Note the reading so you can tell a health professional if needed.

Check the instructions supplied with your thermometer before use. Place the thermometer inside the top of the armpit, and do not let taking a temperature delay urgent or emergency help.

If your baby has just had a bath or has been wrapped in a blanket, wait a few minutes and check again. Do not wait if your baby's age and temperature mean they need urgent assessment, or if they have an emergency sign.

When not to wait and recheck

Do not delay help to take another reading if your baby is seriously struggling to breathe, cannot be woken, is not responding normally, looks blue, unusually pale or blotchy, has a rash that does not fade under pressure or has a seizure (fit) for the first time.

Do not wait to recheck if your baby is under 3 months with 38°C or higher, or aged 3 to 6 months with 39°C or higher. The same applies if your baby looks or behaves unusually, is feeding poorly, has drier nappies or is getting worse. You can also seek professional advice below 38°C if something does not seem right or you remain concerned.

When a baby's fever needs emergency or urgent medical help

Call 999 for emergency signs

You do not need to see every sign on the list. One emergency sign is enough to call 999, and you do not need to know what is causing it.

Young-baby temperature thresholds that need urgent assessment

Seek urgent professional assessment now when:

•your baby is under 3 months and has a temperature of 38°C or higher;

•your baby is aged 3 to 6 months and has a temperature of 39°C or higher.

These readings mean your baby needs urgent help; they do not identify the cause. The service to contact differs across the UK and is set out in the next section. Babies under 6 months can be difficult to assess by phone, so follow any advice to have your baby examined in person; a telephone conversation does not always replace a face-to-face assessment.

Other signs that mean you should get professional advice

Contact the urgent service for the part of the UK where you are if:

• Your baby is feeding much less than usual or feeding has changed noticeably.
• Nappies are drier than usual, or you notice other signs of dehydration.
• Your baby is unusually quiet, listless or behaving differently.
• The fever has lasted for 5 days or more.
• Your baby's symptoms are worsening.
• You remain worried, even if the temperature is below a stated threshold.

How long the fever lasts does not show, on its own, how serious the illness is. A shorter fever is not automatically safe, and a successful feed or a period of playfulness cannot rule out a serious illness.

Which service to contact in England, Wales, Scotland and Northern Ireland

A baby may need urgent assessment anywhere in the UK, but the service names and routes differ. Use the route for the part of the UK where you are:

England

For a baby under 3 months with 38°C or higher, or aged 3 to 6 months with 39°C or higher, call NHS 111 or your GP surgery now. Call 999 for the emergency signs listed above.

Wales

For the same young-baby temperature thresholds, call NHS 111 Wales or your GP surgery now. Call 999 for emergency signs.

Scotland

Follow current NHS Inform fever guidance. It places a temperature of 38°C or above in a baby under 3 months in its 999 section, subject to its specific post-vaccination advice. For other fever concerns, contact your GP and phone 111 when the GP is closed. This is Scotland-specific advice.

Northern Ireland

NHS 111 is not the Northern Ireland route. Contact your GP, or the local GP out-of-hours service if the need is urgent and cannot wait for the surgery to reopen. Call 999 for a life-threatening emergency. Northern Ireland guidance does not link the young-baby temperature thresholds to one particular service, so seek urgent professional assessment rather than waiting at home.

If a phone service is the right route where you are, call promptly and stay with your baby where possible so you can answer questions.

What to have ready when you call

If NHS 111 is the correct service where you are, call 111 for a baby rather than using 111 online; 111 online is for people aged 5 and over. Be ready to say who and where you are, why you are calling and that the concern is about your baby. Stay with your baby where possible so you can answer questions about what you are seeing.

Do not delay the call to prepare a long list. If your baby worsens while you are waiting for a callback, contact the service again. Call 999 if a life-threatening sign appears.

What to do while arranging or waiting for help

These steps can support your baby while you arrange the right help, but they do not replace assessment and must not delay urgent care.

Fluids, milk feeds and comfort

• Offer regular fluids if your baby is willing and able to drink.
• Continue breastfeeding or usual milk feeds if your baby will take them.
• Keep your baby comfortable.
• Do not sponge or undress your baby to force the temperature down.

Poor feeding, an inability to take fluids or drier nappies are reasons to seek professional advice rather than continuing home care alone.

What cannot tell you that your baby is safe

Do not assume your baby is safe because of the thermometer reading, one feed, a short period of playfulness or whether paracetamol or ibuprofen changes the temperature. A fall or lack of fall after medicine cannot show whether an illness is serious.

If your baby is distressed and you are considering medicine, check that it is suitable for them. Follow the label and leaflet, and ask a pharmacist, GP or another healthcare professional if you are unsure. Do not let medicine delay urgent assessment or use it as a reason to wait.

If your baby gets worse while you are waiting

Contact the service again if symptoms worsen while you are waiting for advice or a callback. Call 999 if any of the life-threatening signs listed above appear.

Trust your instincts. You know what is usual for your baby. If they seem different from usual or you are still worried, seek professional advice even when the temperature is below a stated threshold.