Symptom19 min read

Fever in children

Detail level

Fever in a child is a temperature of 38°C or more. It is usually a natural response to an infection such as a cold and usually settles within 1 to 4 days. What matters is watching how the child is, giving fluids and knowing the signs that need help — above all, fever in a baby under 3 months.

The NHS counts 38°C or more as a fever, and MedlinePlus says the cut-off depends on where it is measured (38°C rectal, 37.5°C oral, 37.2°C under the arm). Most fevers come from infections — colds and ear, throat, urine, gut and chest infections — and some vaccines can raise it for a day or two. Give fluids and watch the child, and give a fever medicine only if the child is distressed, never aspirin under 16. A baby under 3 months with 38°C or more needs medical assessment the same day.

Sources differ in the details: the lower age limit for ibuprofen is 3 months for the NHS and 'not 6 months or younger' for MedlinePlus; the NHS and NICE advise against sponging while MedlinePlus says a lukewarm bath may help; the NHS advises getting advice if fever lasts 5 days or more, and the AAP if it lasts more than 24 hours under age 2 or 3 days from age 2. Febrile seizures affect 3 or 4 in every 100 children between 6 months and 5 years (AAP); they are usually harmless and are not prevented by fever medicine, but a first seizure or one lasting more than 5 minutes needs emergency help.

In one minute¹²³⁴

What is it?: A body temperature of 38°C or more, usually a natural response to fighting an infection.
Who is usually affected?: Very common in young children; babies under 3 months most need a prompt medical check.
Acute or chronic?: The temperature usually returns to normal within 1 to 4 days.
Main symptoms: The back or chest feels hot, sweating, feeling unwell, plus symptoms of the cause such as a cough or ear or throat pain.
Red flags?: Yes: a baby under 3 months with 38°C, being very drowsy or hard to wake, difficulty breathing, a rash that does not fade when pressed, a stiff neck, or a seizure.
Preventable?: Febrile seizures cannot be prevented; in hot weather: enough fluids, light clothing, and never leave a child in a parked car.

What is it?

A fever is a temporary rise in body temperature in response to illness or infection. It is an important part of the body's defence, because most germs grow best at normal body temperature (MedlinePlus). The AAP sees it as a sign that the child's immune system is working.

Normal temperature is about 37°C, with a normal range of 36.4°C to 37.5°C. It varies with age, activity, clothing and time of day — usually highest in the late afternoon and early evening — and infants run slightly higher than older children (AAP).

When does a child's temperature count as a fever? (MedlinePlus)
Where measured	Fever at
Rectum	38°C (100.4°F) or higher
Mouth	37.5°C (99.5°F) or higher
Under the arm	37.2°C (99°F) or higher

The NHS uses a single cut-off: a high temperature is 38°C or more.

Signs of a fever: The back or chest feels hotter than usual to touch (NHS).
Sweating, a flushed face and more thirst than usual (NHS and AAP).
Looks or feels unwell (NHS).
Symptoms of the cause itself, such as ear, throat or tummy pain or a rash, which help identify it (AAP).
Reassuring signs: The child is still playing, eating and drinking well, alert and smiling, with normal skin colour (MedlinePlus).
Looks well when the temperature comes down (MedlinePlus) and plays and interacts again after fever medicine (AAP).

The temperature usually returns to normal within 1 to 4 days (NHS). The number alone does not show how serious the illness is: a simple viral infection can cause 38.9°C to 40°C without a serious problem, while some serious infections cause no fever or a low temperature, especially in infants (MedlinePlus).

Possible causes

Infection, the commonest cause: colds and coughs, ear, throat and sinus infections, urinary and gut infections, and respiratory illnesses such as RSV, croup, flu and pneumonia (AAP).
Chickenpox and tonsillitis are also common causes (NHS).
Vaccinations can cause a high temperature (NHS); MedlinePlus says some cause a mild fever for 1 or 2 days.
Less common causes: inflammatory or autoimmune conditions, some cancers and some medicines (MedlinePlus).

The most serious causes are sepsis and meningitis, which is why the warning signs at the bottom of this page matter (AAP).

Teething: it may raise the temperature slightly within the normal range but does not cause a true fever — not above 37.8°C according to MedlinePlus — and if it reaches 38°C it is probably not teething, so ask the doctor (AAP).

How it is assessed

Feeling the forehead or skin is not an accurate way to measure temperature, and forehead strips are not reliable (AAP). A digital thermometer is best.

The NHS method: put the digital thermometer at the top of the armpit, gently close the child's arm over it and keep it pressed to the side of the body, and leave it for as long as the leaflet says.

Ways to measure, according to the AAP
Method	What the AAP says
Rectum	Most accurate, especially for babies under 3 months
Forehead (temporal artery)	Next most accurate; usable at any age
Ear	From 6 months; before that the ear canal is too small for an accurate reading
Mouth	Not recommended before age 4
Under the arm	Least accurate, but fine for screening at any age

Do not use a glass mercury thermometer: it can break and release toxic mercury (AAP).
Wait 30 minutes after a hot or cold drink before an oral reading, and 15 minutes after coming in from the cold before an ear reading (AAP).
Keep a rectal thermometer for that use only, and clean thermometers before and after use (AAP).

NICE guidance for professionals says a parent's report of fever should be taken seriously, and that the length of a fever alone should not be used to predict serious illness.

Sources differ on the preferred method: the NHS advises a digital armpit reading, the AAP rates rectal as most accurate under 3 months, and NICE (for professionals) says not to use the mouth or rectum routinely under 5 years. Follow your child's doctor's advice.

Self-care

Give plenty of fluids, and if the baby is breastfed keep breastfeeding as normal (NHS).
Offer food if the child wants it, and do not force them to eat (NHS and MedlinePlus).
Good fluids: water, soup and ice lollies; for young children avoid too much fruit juice and sports drinks (MedlinePlus).
Look out for signs of dehydration and check on the child regularly, including during the night (NHS).
Keep the child at home, away from nursery or school, while the fever lasts, and tell them about the illness (NICE).
Light clothing: one light layer and one light blanket (MedlinePlus), without piling on clothes and bedding and without stripping the child (NHS and NICE).

Do not sponge the child or undress them to cool them; a high temperature is a natural response to infection (NHS, and also NICE). Avoid cold baths, ice and alcohol rubs, which cause shivering and raise the core temperature (MedlinePlus). MedlinePlus says a lukewarm bath may help after medicine, which the NHS and NICE do not advise.

Fever medicines: the main purpose of treating a fever is to help the child feel better if they are uncomfortable or in pain (AAP), and the goal is to lower the fever, not eliminate it (MedlinePlus). The NHS advises paracetamol or ibuprofen only if the child is distressed or uncomfortable, checking that the product suits the child's age, and getting advice if it does not help.

No aspirin under 16 unless a doctor prescribes it, because it is linked to Reye's syndrome, a very rare condition (NHS).
Do not give paracetamol and ibuprofen together, and do not alternate them unless a doctor or nurse tells you to (NHS and NICE).
Paracetamol: not for a baby under 2 months (NHS).
Ibuprofen: according to the NHS, not for a child under 3 months, under 5kg, with chickenpox or dehydration, or with asthma unless a doctor advises it; MedlinePlus says not for children aged 6 months or younger.

This page gives no doses. A child's fever medicine dose is based on body weight (MedlinePlus); follow the leaflet of a product suitable for the child's age or ask a pharmacist or doctor, and give no medicine to a baby aged 3 months or younger before talking to a doctor (MedlinePlus).

Asthma in childrenCondition

Febrile seizures

A febrile seizure (febrile convulsion) is a fit that can happen with a high temperature. It is frightening but usually not serious and is unlikely to harm the child or cause long-term effects (NHS). It affects 3 or 4 in every 100 children between 6 months and 5 years, most often around 12 to 18 months (AAP); the NHS gives 6 months to 6 years.

It usually happens in the first 24 hours of an illness, not necessarily at the peak temperature (MedlinePlus). Signs include the body stiffening, shaking or jerking, loss of consciousness and not responding, perhaps vomiting or wetting, then sleepiness, irritability or confusion for up to an hour. It usually lasts 2 to 3 minutes and rarely more than 10 minutes (NHS).

1
Note the timeNote when the seizure starts and ends (NHS).
2
Keep the child safeProtect the head with your hands or something soft, and move dangerous objects away (NHS). MedlinePlus advises having the child on a safe floor away from furniture and sharp objects, with a blanket under them on a hard floor, and loosening tight clothing around the neck.
3
Don't restrain or put anything in the mouthDo not try to hold the child still (NHS and MedlinePlus), put nothing in the mouth — they will not swallow their tongue (AAP) — and do not try to cool them by undressing them or with cold water (NHS).
4
Recovery positionWhen it ends, or if the child vomits or saliva builds up, turn them on their side, check nothing is blocking the mouth or throat, and stay with them (NHS and MedlinePlus).
5
Get helpA first febrile seizure needs a hospital check, and a seizure lasting more than 5 minutes is an emergency (NHS and AAP). Do not drive to the emergency department yourself if the child is still seizing or unconscious — call an ambulance (NHS).

Febrile seizures cannot be prevented, and fever medicines lower the temperature but do not prevent them and should not be used for that (NHS, AAP and NICE). They come back in about 50% of children whose first was before age 1, and 30% of healthy children whose first was later (AAP). A febrile seizure is not epilepsy; there is a slightly higher, rare chance of epilepsy later (NHS), and no evidence that a simple febrile seizure causes brain damage or learning problems; most children outgrow them by age 5 (MedlinePlus).

Signs of dehydration

The NHS advises looking out for signs of dehydration in a child with a fever, including:

A sunken soft spot (fontanelle) on top of a baby's head, and sunken eyes (NHS and NICE).
Few or no tears when crying, and a dry mouth (NHS and NICE).
Fewer wet nappies than usual (NHS).
Drowsiness or irritability (NHS).

What to do: keep breastfeeding or formula feeding in small, frequent amounts; give extra sips of water to babies on formula or solids (boiled, cooled water under 6 months); and give regular small sips of an oral rehydration solution a pharmacist recommends. Do not dilute formula, and do not give young children fruit juice or fizzy drinks (NHS).

Hot weather

Heatstroke is different from fever: it is caused by environmental heat and dehydration, not infection, and can raise body temperature above 40.5°C; a baby can get it if overdressed in hot, humid weather (AAP). It is an emergency; see heat illness and heatstroke.

Babies and young children rely on others to keep them cool and hydrated; give enough fluids, avoiding very cold or very sugary drinks (CDC).
Loose, lightweight, light-coloured clothing (CDC).
Never leave a child in a parked car, even with the windows open: the temperature inside can rise by about 11°C (20°F) within 10 minutes (CDC).

Limits of this information

Sources differ on several limits, and each number is given with its source: the age limit for ibuprofen (3 months for the NHS, over 6 months for MedlinePlus), lukewarm sponging, how long a fever can last before getting checked (5 days for the NHS; 24 hours under age 2 or 3 days from age 2 for the AAP), and the threshold for babies aged 3 to 6 months (39°C for the NHS).

Emergency and health-advice numbers differ between countries, and the sources here are British and American; use the «Emergency» button at the top of the page to find yours.

This page gives no medicine doses, does not replace a doctor's assessment, and does not cover folk remedies, for which there are no reliable sources.

When do you need urgent help?

Call emergency services now 998

A stiff neck, a very bad headache, a rash that does not fade when you press a glass against it, or being bothered by light.¹⁴
A child with fever who cannot walk or refuses to move an arm or leg.⁴
Unusually cold hands and feet, or blue, grey, pale or blotchy skin, lips or tongue.¹⁴
Very drowsy and hard to wake, crying that cannot be calmed, confusion, or not responding as usual or losing interest in feeding and play.¹⁴
Difficulty breathing (grunting, or the tummy sucking in under the ribs), very fast breathing, or breathlessness that continues after the nose is cleared.¹⁴
A first febrile seizure, or one lasting more than 5 minutes, affecting one side of the body, with difficulty breathing, recurring within 24 hours, or followed by unusual sleepiness for more than an hour.²¹⁰
Suspected heatstroke, for example after being in a hot car or overdressed in hot, humid weather.⁶
Signs of dehydration with pale, blotchy or cold skin, fast breathing, confusion or being hard to wake — this may be shock.¹²

Get urgent care today

A baby under 3 months with a temperature of 38°C or more, even with no other symptoms.¹⁶
A baby aged 3 to 6 months with 39°C or more (NHS); MedlinePlus gives the same threshold up to 12 months.¹⁴
Signs of dehydration: drier nappies, sunken eyes, crying without tears, or a sunken soft spot.¹¹²
Fever with a new rash or bruises, severe throat or ear pain, pain when passing urine, or repeated vomiting or diarrhoea.¹¹³⁴
A temperature repeatedly above 40°C at any age, a child who looks very ill, or who is not eating and not their usual self and you are worried.¹³¹
Fever in a child with a weak immune system, a heart condition or a serious long-term illness, or after recent travel abroad.¹³⁴
Fever lasting 5 days or more (NHS), or fevers that come and go for a week or more (MedlinePlus).¹⁴

See your doctor within days

Fever for more than 24 hours in a child under 2, or more than 3 days in a child aged 2 or older, or a child who still seems sick after the fever comes down or is getting worse (AAP).¹³

Educational content only — no diagnosis, and no substitute for a clinician.

Common questions

What temperature counts as a fever in a child?

38°C or more, according to the NHS. MedlinePlus says the cut-off depends on where it is measured: 38°C rectal, 37.5°C oral and 37.2°C under the arm.¹⁴

What is the best way to take a child's temperature?

With a digital thermometer; the NHS advises putting it at the top of the armpit. The AAP says a rectal reading is most accurate under 3 months, followed by a forehead thermometer, with ear thermometers from 6 months and oral from age 4. Feeling the forehead is not enough, and mercury thermometers should not be used.¹⁷⁶

How long does a fever usually last in children?

The temperature usually returns to normal within 1 to 4 days (NHS). The NHS advises getting advice if it lasts 5 days or more, and the AAP if it lasts more than 24 hours in a child under 2 or 3 days in an older child.¹¹³

Is the fever itself harmful to a child?

Fever is usually part of the body's defence against infection. MedlinePlus says brain damage from a fever is unlikely unless it is over 42°C, and that fevers from infection seldom go above 40.6°C unless the child is overdressed or in a hot place. How the child is and the warning signs matter more than the number alone.⁴⁵

Should I sponge my child or take off their clothes to bring the fever down?

The NHS and NICE advise against sponging the child, stripping them or over-wrapping them; light clothing and a light cover are enough. Avoid cold water, ice and alcohol rubs, which cause shivering (MedlinePlus).¹⁸⁴

Can I give my child aspirin for a fever?

No — do not give aspirin to anyone under 16 unless a doctor prescribes it, because it is linked to Reye's syndrome, a very rare condition (NHS).⁹¹

Can I alternate paracetamol and ibuprofen for my child?

Do not alternate them or give them together unless a doctor or nurse tells you to (NHS and NICE). Give one only if the child is distressed, check the product suits the child's age, and follow the leaflet or ask a pharmacist about the dose.¹⁸

Do fever medicines prevent febrile seizures?

No — paracetamol and ibuprofen lower the temperature but do not prevent febrile seizures (AAP), and should not be used for that purpose (NICE).¹⁰⁸

Can a febrile seizure cause brain damage or epilepsy?

A simple febrile seizure is harmless; there is no evidence it causes brain damage, epilepsy or learning problems, and most children outgrow them by age 5 (MedlinePlus). It is not epilepsy, though there is a slightly higher, rare chance of epilepsy later (NHS).¹¹²

Does teething cause a fever?

Teething may raise the temperature slightly within the normal range but does not cause a true fever (AAP), and not above 37.8°C (MedlinePlus). If it reaches 38°C the cause is probably not teething, so ask the doctor.⁶⁴

What should I do if my child has a febrile seizure?

Note the start time, protect the head and move dangerous objects away, do not restrain them or put anything in the mouth, then turn them on their side afterwards and stay with them. Call an ambulance if it is the first seizure, lasts more than 5 minutes or breathing is difficult (NHS and AAP).²¹⁰¹¹

Questions for your doctor

What is the best way to measure my child's temperature at this age?
Which fever medicine suits my child's age and weight, and what is the dose?
What do you think is causing the fever, and are tests needed?
When should I come back if the fever does not come down?
How can I tell my child is drinking enough?
If my child has had a febrile seizure, how likely is another, and what should I do?

References

1
NHS. High temperature (fever) in children. www.nhs.uk/conditions/fever-in-children/
Health agencies & guidelines · Accessed 2026-10-11
2
NHS. Febrile seizures. www.nhs.uk/conditions/febrile-seizures/
Health agencies & guidelines · Accessed 2026-10-11
3
CDC. Infants and Children and Heat. www.cdc.gov/heat-health/risk-factors/infants-and-children.html
Health agencies & guidelines · Accessed 2026-10-11
4
MedlinePlus. Fever. medlineplus.gov/ency/article/003090.htm
Health agencies & guidelines · Accessed 2026-10-11
5
HealthyChildren.org (American Academy of Pediatrics). Signs and Symptoms of Fever. www.healthychildren.org/English/health-issues/conditions/fever/Pages/Signs-and-Symptoms-of-Fever.aspx
Health agencies & guidelines · Accessed 2026-10-11
6
HealthyChildren.org (American Academy of Pediatrics). Fever and Your Baby. www.healthychildren.org/English/health-issues/conditions/fever/Pages/Fever-and-Your-Baby.aspx
Health agencies & guidelines · Accessed 2026-10-11
7
HealthyChildren.org (American Academy of Pediatrics). How to Take Your Child's Temperature. www.healthychildren.org/English/health-issues/conditions/fever/Pages/How-to-Take-a-Childs-Temperature.aspx
Health agencies & guidelines · Accessed 2026-10-11
8
NICE. Fever in under 5s: assessment and initial management (NG143) - Recommendations. www.nice.org.uk/guidance/ng143/chapter/Recommendations
Health agencies & guidelines · Accessed 2026-10-11
9
NHS. Reye's syndrome. www.nhs.uk/conditions/reyes-syndrome/
Health agencies & guidelines · Accessed 2026-10-11
10
HealthyChildren.org (American Academy of Pediatrics). Febrile Seizures in Children. www.healthychildren.org/English/health-issues/conditions/fever/Pages/Febrile-Seizures.aspx
Health agencies & guidelines · Accessed 2026-10-11
11
MedlinePlus / NLM. Febrile seizures. medlineplus.gov/ency/article/000980.htm
Health agencies & guidelines · Accessed 2026-10-11
12
NHS. Dehydration. www.nhs.uk/conditions/dehydration/
Health agencies & guidelines · Accessed 2026-10-11
13
HealthyChildren.org (American Academy of Pediatrics). Fever: When to Call the Pediatrician. www.healthychildren.org/English/health-issues/conditions/fever/pages/When-to-Call-the-Pediatrician.aspx
Health agencies & guidelines · Accessed 2026-10-11

Review status: Edited content · Last updated: 2026-10-11

Change log

2026-10-11 — Page created.