My child's temperature is 40°C. Does a very high number always mean something serious?

Not necessarily. NICE guidance is explicit that in children over six months, the height of the temperature alone should not be used to identify serious illness. A child who is alert, drinking, and responding to you after medicine is more reassuring than the number on the thermometer. That said, do check for the signs listed in this article — particularly skin colour, responsiveness, and any rash — and contact your doctor if you are unsure.

Should I alternate paracetamol and ibuprofen to keep the fever down?

NHS and NICE guidance advises against routinely alternating the two medicines. Consider switching to the other medicine only if your child remains distressed before their next scheduled dose of whichever was given first. Using both together, or alternating them as a routine, is not recommended without medical guidance.

My child had a febrile seizure. Is it likely to happen again, and will it cause lasting harm?

Febrile seizures are frightening to witness but the AAP confirms clearly that simple febrile seizures do not cause brain damage, nervous system problems, intellectual disability, or long-term health effects. They affect around 3 to 5% of young children and are most common between 6 months and 5 years. There is a modest chance of recurrence with future fevers, but the risk of developing epilepsy after a simple febrile seizure is extremely low. Do discuss the episode with your doctor.

When does my feverish child actually need antibiotics?

Only when a doctor has assessed them and identified a bacterial infection — such as a bacterial ear infection, urinary tract infection, or strep throat confirmed on examination or test. The vast majority of childhood fevers are caused by viruses, and antibiotics have no effect on viruses. Giving them unnecessarily can cause side effects and contributes to antibiotic resistance.

How do I know if my child is getting dehydrated during a fever?

The most useful signs to watch for are: crying with no tears, a noticeably dry mouth or lips, and fewer wet nappies or trips to the toilet than usual. Offering small, frequent sips of fluid — water, breast milk, or formula for infants — is the most important thing you can do at home. If your child is refusing to drink or is vomiting everything, that is a reason to check in with your doctor.

Fever in Children: What's Normal and When to Seek Care

Your child feels warm. You check — 38.9°C. Your stomach tightens. Should you give medicine now? Go to the hospital? Wait? Fever is one of the most common reasons parents search online at midnight, and the anxiety around it is understandable. But the evidence from major health bodies is clear and reassuring: in most children, fever is the body doing exactly what it should. Knowing what to watch — rather than what to fear — puts you back in the driver's seat.

What fever actually is, and why the body produces it

A temperature of 38°C (100.4°F) or higher is the threshold that both the NHS and the American Academy of Pediatrics (AAP) use to define fever. Below that, your child is simply a little warm. Above it, the immune system is at work — fever is part of the body's natural response to infection.

The AAP states plainly that fever is a physiologic mechanism with beneficial effects in fighting infection, and that there is no evidence it worsens the course of an illness or causes long-term neurological complications. In other words, fever is a tool the body uses, not a sign that something has gone wrong. Most fevers in children resolve on their own within one to four days.

1 to 4 daysTypical fever resolution time

Comfort matters more than the number on the thermometer

This is one of the most important shifts in how paediatric guidelines now frame fever care. The AAP's clinical guidance is explicit: the primary goal is to improve the child's overall comfort, not to normalise their body temperature. If your child has a temperature of 39°C but is alert, playing, drinking fluids, and responding normally to you, that is a far more reassuring picture than a child who looks pale and limp at 38.2°C.

Paracetamol and ibuprofen are the only antipyretics recommended for children based on strong evidence of their safety and efficacy. The key guidance from both NICE and the NHS is to give them only if your child appears distressed — not simply to bring the thermometer reading down. Always dose by your child's weight, not their age, and follow the instructions on the packaging carefully; research shows a notable proportion of caregivers give medicine at intervals that are too short.

Give paracetamol or ibuprofen only if your child seems uncomfortable or distressed — not to chase a number.
Do not give aspirin to any child under 16 years old (risk of a rare condition called Reye's syndrome).
Do not give ibuprofen to children under 3 months, those under 5 kg, or those with chickenpox, dehydration, or asthma (without a doctor's approval).
Avoid paracetamol in infants under 2 months unless directed by a doctor.
Do not routinely alternate paracetamol and ibuprofen; consider switching only if distress continues before the next scheduled dose of whichever was given first.
Do not use cold sponging, ice packs, or undressing to bring temperature down — sponging can cause shivering, which may raise temperature further.

How your child looks is the most important signal

NICE's clinical guideline for feverish children under five uses a traffic-light framework — Green, Amber, and Red — based not on the temperature reading alone but on how the child looks and behaves. A child in the Green category is normal in colour, smiles and responds to your voice, cries normally, and has a moist mouth. This is the most common picture, and it is a reassuring one.

NICE is clear that in children over six months, the height of the temperature should not be used in isolation to identify serious illness. A child who is playing and drinking after a dose of medicine is providing you with genuinely useful information that no thermometer reading alone can give you.

Signs that are worth checking promptly

Certain changes in your child's appearance or behaviour are worth acting on quickly. NICE's guidance identifies the following as signs that need same-day professional assessment or, in some cases, immediate attention.

The non-blanching rash test

One specific check is worth knowing: press the bottom of a clear glass firmly against any rash on your child's skin. If the rash fades under pressure, it is blanching and generally less concerning. If it does not fade, this is a non-blanching rash and needs prompt assessment. NICE guidance identifies this as a sign that could indicate meningococcal disease, particularly if the spots are larger than 2 mm, your child looks unwell, or neck stiffness is present.

Fever in very young infants: a special note

The rules are meaningfully different for the youngest babies. In an infant under 3 months old, any temperature of 38°C or higher is a reason to contact a doctor promptly — regardless of how the baby appears. Young infants have immune systems that are still developing, and the usual visual reassurance signs are less reliable. For infants aged 3 to 6 months, a temperature at or above 39°C (NHS) or 38.3°C (AAP) is a reason to seek medical advice.

It is also worth knowing that in young infants with bacterial meningitis, the classic signs — neck stiffness, a bulging fontanelle, and a high-pitched cry — are often absent. This is one reason why clinical assessment by a health professional matters more than a home checklist for this age group.

Under 3 months — any fever of 38°C or higherAge where any fever needs same-day medical contact

A note on febrile seizures

Febrile seizures — brief convulsions associated with fever — affect around 3 to 5% of children between six months and five years of age and are most common around 12 to 18 months. They are frightening to witness, but the AAP is clear that simple febrile seizures do not cause brain damage, nervous system problems, paralysis, intellectual disability, or death. The risk of developing epilepsy after a simple febrile seizure is extremely low.

If a seizure occurs: place your child on the floor away from hard objects, turn their head gently to the side to allow drainage, and do not put anything in their mouth. Most febrile seizures end on their own in under five minutes. If a seizure continues beyond five minutes, call emergency services.

Why most fevers do not need antibiotics

The large majority of childhood fevers are caused by viruses — colds, flu, roseola, and other common infections that the immune system clears naturally. Antibiotics do not work against viruses. Giving them when they are not needed does not speed recovery and can cause side effects including rash and diarrhoea, while contributing to antibiotic resistance — a serious global health concern. Research published in 2024 found that antibiotics did not shorten fever duration and were associated with longer hospital stays in children with confirmed viral respiratory infections.

If a doctor does prescribe antibiotics after assessing your child, that assessment has identified a bacterial cause. But asking for them 'just in case' is something paediatric guidelines across the NHS, NICE, and the AAP advise against for good reason.

A simple at-home action plan

Check your child's temperature with a reliable thermometer. 38°C or above confirms a fever.
Observe how they look and act — are they alert, responding to you, drinking? This tells you more than the number.
Offer fluids frequently — water, breast milk, or formula for infants. Keeping your child hydrated is the single most important home action. Signs of dehydration to watch for: no tears when crying, a dry mouth, and fewer wet nappies than usual.
Give paracetamol or ibuprofen only if your child is uncomfortable — follow weight-based dosing on the packaging. Never give aspirin.
Skip the sponging — cool or tepid sponging is not recommended and can make your child feel worse.
Monitor over the coming days — most fevers settle within one to four days. Note any changes in skin colour, responsiveness, or breathing.
Check in with your doctor if your child is under 3 months with any fever; if fever lasts beyond 24 hours (under 2 years) or 3 days (2 years and older); or if any of the signs in the callout above appear.