When should I see a doctor for my child's fever?
It's one of the hardest decisions in parenting: is this a normal-ish fever you can ride out at home, or is this the one that needs a doctor? Calpol doesn't have a chart for that.
The honest answer: the temperature number matters less than two things — your child's age, and how they're behaving. Here are the rules the NHS uses, the red flags every parent should know, and what to track before you call.
The quick answer
- Under 3 months + any fever (38°C+): call 111 or go to A&E.
- 3–6 months + fever 39°C or above: call 111.
- Any age + non-blanching rash, breathing difficulty, unresponsiveness, blue lips, or a seizure: 999 or A&E immediately.
- Fever lasting more than 5 days (3 days in an infant): see your GP.
- Above all: trust your gut. If something feels off, call 111. It's free.
Temperature thresholds by age
UK NICE guidance and the NHS use a "traffic light" system to grade fever risk in children under 5. The full version is for clinicians, but the headline thresholds are clear:
| Age | Any fever (38°C+) | High fever (39°C+) |
|---|---|---|
| Under 3 months | Call 111 or A&E | Urgent — A&E |
| 3–6 months | Monitor closely, call GP if worried | Call 111 |
| 6 months – 5 years | Treat at home unless red flags | Monitor; call 111 if behaviour worsens |
| 5+ years | Treat at home unless red flags | Monitor; call 111 or GP if persistent |
The thresholds get stricter the younger the child because young babies can't show illness the same way older kids can. A 2-week-old with a fever could be brushing off a cold, or could have a serious bacterial infection — and you can't tell from the outside.
Red flags: call 111 or 999 regardless of temperature
These signs override the thermometer. Any of them in a feverish child means you call now, not later.
Call 999 / go to A&E immediately:
- A non-blanching rash — a rash that doesn't fade when you press a glass against it. Classic meningitis sign.
- Difficulty breathing — fast breathing, grunting, drawing in the chest under the ribs, blue tinge to lips or face.
- Unresponsive or very drowsy — hard to wake, floppy, doesn't respond to your voice or touch as they normally would.
- A fit or seizure — including a "febrile convulsion" you've not seen before.
- Pale, mottled, or blue skin — particularly hands, feet, or around the mouth.
- A baby with a bulging fontanelle (the soft spot on top of the head sticking out).
- Unusual high-pitched or weak cry in a baby.
Call NHS 111:
- Fever above 38°C in a baby under 3 months
- Fever above 39°C in a baby 3–6 months
- Fever lasting more than 5 days (3 in an infant)
- Persistent vomiting that prevents drinking
- Signs of dehydration (no wet nappy for 6+ hours, sunken soft spot in babies, no tears when crying, dry mouth)
- Fever combined with stiff neck or severe headache
- Pain in the abdomen or limbs that won't ease
- A fever that comes back after seeming to resolve
- You're worried — full stop
How to actually take a child's temperature
An accurate reading matters. Some general rules:
- Under 4 weeks: use an electronic underarm thermometer.
- Over 4 weeks: electronic underarm or infrared tympanic (ear). Ear thermometers can be inaccurate in children under 4 weeks because the ear canal is too small.
- Don't use: forehead strips, oral thermometers in young children, mercury thermometers (no longer sold for safety reasons).
- If using an ear thermometer, take three readings and use the highest — they can vary.
- Always note the time. A reading on its own isn't useful; the trend over hours is.
What to track before you call 111
Triage nurses ask the same things every time. Having these to hand makes the call faster and the assessment more accurate:
- Child's age and weight (approximate is fine)
- Highest temperature recorded and the time
- When the fever started
- Doses given: what, how much, when. Both Calpol and ibuprofen
- Other symptoms: cough, runny nose, rash, vomiting, diarrhoea, refusing to eat or drink, behaviour change
- Any rash and whether it fades when pressed
- Wet nappies / urination in the last 6 hours
- Pre-existing conditions or recent vaccinations
What a "normal" childhood fever looks like
Not every fever is a crisis. Viral illnesses cause most childhood fevers, and most resolve in 3 to 5 days without specific treatment. A typical viral fever:
- Peaks at 38–40°C, often higher in the evenings
- Responds (partly) to paracetamol or ibuprofen
- Comes with other symptoms — cough, sniffles, sore throat, mild rash
- Resolves within 5 days
- The child is grumpy but consolable, drinks fluids, has wet nappies
The medicine handles the discomfort while the body handles the illness. You're managing, not curing.
The "look at the child, not the thermometer" principle
This is what most experienced doctors tell parents. Two children with identical temperatures can be in very different states. The temperature is a signal, not the whole picture. More important:
- Are they drinking? Wet nappies / urination in the last 6 hours = good sign.
- Are they responsive? Making eye contact, recognising you, smiling occasionally = good.
- Are they consolable? Quietens when picked up, distractible with a favourite toy = good.
- Are they breathing easily? Slow, regular, no chest pulling = good.
- Is their skin colour normal? Pink lips, warm hands, no mottling = good.
A child running 39.5°C who's drinking apple juice and watching cartoons is in a different category to a child running 38.2°C who's listless and floppy. The second child needs assessment regardless of the lower number.
Febrile convulsions
About 1 in 20 children between 6 months and 5 years has a febrile convulsion — a seizure triggered by a sudden rise in temperature. They're frightening to watch but usually harmless on their own. The child stiffens, their limbs jerk, and they may briefly lose consciousness. Most last under 5 minutes.
If it happens:
- Lay your child on their side, head tilted back slightly
- Don't put anything in their mouth
- Time the seizure
- Call 999 if it's their first one, if it lasts more than 5 minutes, or if they don't return to themselves within 30 minutes
- Even if everything seems to resolve, see a GP afterwards
Frequently asked questions
When is a child's fever too high?
Under 3 months: any fever (38°C+) needs urgent assessment. 3–6 months: 39°C or above. Older children: the number matters less than behaviour.
Should I take my child to A&E with a fever?
Go to A&E or 999 with fever + any of: non-blanching rash, breathing difficulty, drowsiness, blue skin, seizure, or signs of dehydration in a baby. Otherwise call NHS 111 first.
How long can a fever last in a child?
Most viral fevers last 3 to 5 days. More than 5 days, or 3 in an infant, see a GP.
Is a temperature of 39°C dangerous?
In a baby under 6 months, yes — call 111. In an older child, 39°C alone isn't necessarily dangerous, but combined with red flags (breathing problems, rash, drowsiness) it is.
My child's temperature came down with Calpol then went back up — is that bad?
No, that's normal. Calpol manages fever for 4–6 hours; when it wears off the fever can return. What matters is whether your child is otherwise improving over 3–5 days.
Can I give Calpol before going to A&E?
Yes. It won't mask anything important and may make your child more comfortable for the wait. Tell the triage nurse what you've given and when.
How Dosey helps
When you do call 111 or visit a GP, the first question is "what medicine have they had and when?". Dosey shows the last 24 hours of doses and temperatures at a glance, including who logged each entry — so you don't have to remember whether you or your partner gave the last Calpol at 11pm or 11:30pm.
If you're worried right now, stop reading and call NHS 111 — it's free and available 24/7. For breathing difficulties, unresponsiveness, a non-blanching rash, or seizures: call 999.
This isn't medical advice. Dosey is a record-keeping tool, not a clinic. If you're worried about your child, trust that feeling and call.