Baby fever: when to worry and when to wait
A baby who feels warm to the touch is one of the most unsettling things a new parent faces, especially in the middle of the night. The good news is that most fevers in babies are short-lived and the body is simply doing what it is built to do: fighting off an infection. What matters most is knowing which signs mean you should act straight away and which allow you to watch and wait at home. This guide draws on NHS guidance to help you make that call with confidence.
What is a fever?
A temperature of 38C or above is classed as a high temperature, or fever, in babies and children. A small rise above that threshold is not in itself a measure of how serious an illness is, but age plays a big role in how concerned you should be. A fever in a very young baby needs quicker attention than the same reading in an older infant, because newborns have less-developed immune systems and can deteriorate faster.
Fever is not an illness on its own. It is the body's natural response to infection, a sign that the immune system is active. The vast majority of fevers in babies are caused by common viral infections and settle on their own within a few days.
Age matters: the thresholds to know
The NHS sets different thresholds depending on how old your baby is, because the risks are different at each stage.
- Under 3 months: Contact your GP or call 111 if your baby's temperature reaches 38C or higher. At this age, even a modest fever warrants prompt attention.
- 3 to 6 months: Contact your GP or call 111 if the temperature reaches 39C or higher.
- Over 6 months: The temperature reading alone matters less than how your baby is behaving. Use the emergency signs below to guide your response at any age.
These thresholds are starting points. If you are worried for any reason, you do not need to wait for a number on a thermometer before seeking advice.
When to call 999 immediately
Some signs alongside a fever are serious regardless of how high the temperature is. Call 999 or go to your nearest A&E straight away if your baby has any of these:
- A stiff neck
- A rash that does not fade when you press a glass firmly against the skin
- Sensitivity to light
- A seizure (fit) that is happening for the first time
- Hands or feet that feel unusually cold
- Skin that has turned blue, grey, pale or blotchy
- Being very difficult to wake or unusually drowsy
- Extreme agitation or confusion
- Difficulty breathing, or breathing that is faster than normal
- Not responding to you
This list covers the warning signs the NHS identifies as requiring immediate emergency care. Do not wait to see whether things improve if your baby shows any of them.
When to call 111 or your GP
Outside of the emergency situations above, there are other circumstances where you should seek medical advice without delay. Call 111 or your GP if:
- Your baby is under 3 months and has a temperature of 38C or above
- Your baby is 3 to 6 months and has a temperature of 39C or above
- A fever has lasted more than 5 days at any age
- Your baby has developed a rash alongside the fever
- Your baby is not eating or appears generally unwell in a way that worries you
- There are signs of dehydration (see below)
- Something just does not feel right and you want reassurance
You know your baby better than anyone. Trusting your instincts is always reasonable, and NHS services are there to help you work through it.
Signs of dehydration to watch for
A feverish baby can lose fluid quickly, so keep a close eye on hydration. Contact a doctor if you notice:
- Dry nappies, or far fewer wet nappies than usual
- Eyes that look sunken
- No tears when your baby cries
- A dry mouth
Offer feeds frequently. If you are breastfeeding, continue as normal. Extra breastfeeds are a good way to keep a young baby hydrated during a fever.
Caring for a feverish baby at home
When the situation does not call for emergency care, there is a lot you can do to help your baby feel more comfortable while the fever runs its course. Most fevers clear up on their own within 1 to 4 days.
What helps
- Offer plenty of fluids: breast milk, formula or, for babies on solids, small sips of water
- Continue breastfeeding if your baby will feed
- Offer food if your baby wants it, but do not worry if appetite is reduced
- Check on your baby regularly, including during the night
- If your baby appears distressed or uncomfortable, infant paracetamol can help (not for babies under 2 months)
- Ibuprofen is an alternative for babies over 3 months and weighing more than 5kg, unless they have chickenpox, are dehydrated, or have asthma (unless their doctor has said it is safe)
What not to do
- Do not undress your baby or sponge them with cool water to bring the temperature down
- Do not wrap them in extra layers to make them sweat it out
- Do not give aspirin to anyone under 16
- Do not alternate paracetamol and ibuprofen unless a doctor has specifically advised you to
- Do not give paracetamol to a baby under 2 months old
- Do not give ibuprofen to a baby under 3 months or under 5kg in weight
Always follow the dosing instructions on the medicine packaging for your baby's age and weight, or ask a pharmacist if you are unsure.
How to take your baby's temperature
A digital thermometer used under the armpit is the recommended method for babies. Ear thermometers can be used from 3 months. Strip thermometers placed on the forehead are not reliable for measuring a precise temperature. If the reading from your thermometer does not match how your baby seems, trust your observation and seek advice anyway.
Frequently asked questions
What temperature counts as a fever in a baby?
A temperature of 38C or above is classed as a high temperature in babies and children. Even a small rise to or above this level in a baby under 3 months needs prompt attention.
When should I call 111 or a doctor about my baby's fever?
Always call if your baby is under 3 months and has a temperature of 38C or higher, or if your baby is between 3 and 6 months and the temperature is 39C or higher. At any age, also call if the fever has lasted more than 5 days, your baby is not eating, has a rash, or you notice signs of dehydration.
When should I call 999 for a baby with a fever?
Call 999 immediately if your baby has a stiff neck, a rash that does not fade when pressed with a glass, is very difficult to rouse, has changed skin colour (blue, grey, pale or blotchy), is struggling to breathe, or is having a seizure for the first time. These signs require emergency care regardless of the temperature reading.
Can I give my baby paracetamol or ibuprofen for a fever?
Infant paracetamol can be given to ease discomfort but not before 2 months of age. Ibuprofen can be given from 3 months and only if your baby weighs more than 5kg, but should be avoided if your baby has chickenpox, is dehydrated, or has asthma unless a doctor has approved it. Never give aspirin to a baby or child under 16. Always use the dose on the packaging for your baby's specific age and weight.
How long does a fever usually last in a baby?
Most fevers settle on their own and temperature returns to normal within 1 to 4 days. If a fever continues beyond 5 days, contact a doctor even if your baby seems otherwise well.
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