A fever is the body doing its job. It is part of how the immune system fights an infection, and the fever itself does not harm a child. Most childhood fevers are caused by ordinary viruses, last a few days, and need nothing more than fluids, rest and a parent keeping an eye on things. The useful skill is knowing which few need more than that.
What counts as a fever
A temperature of 38°C (100.4°F) or above. Normal temperature varies a little from child to child and through the day, so a reading just under 38 is not a fever, even if it feels warm to the hand.
To get a reading you can trust, use a digital thermometer under the arm, held in the fold of the armpit with the arm down against the body. Forehead strips are not reliable. Wait a few minutes after a bath, a feed or being wrapped up warm, because all of those push the reading up on their own.
How your child looks and behaves tells you more than the number. A child at 39.5°C who is drinking, grumbling and watching television is usually fine. A child at 38.2°C who is floppy, pale and not interested in anything is the one to worry about.
When to get medical advice, by age
| Age | Get advice if |
|---|---|
| Under 3 months | Any fever of 38°C (100.4°F) or above. See a doctor urgently, the same day, even if the baby seems well. |
| 3–6 months | 39°C (102.2°F) or above. |
| Any age | Above 40°C (104°F), or a fever of any height together with any of the red flags below. |
The under-3-months rule is the one to remember. Very young babies can have a serious infection with few other signs, so the fever alone is the reason to be seen.
Outside those rules, a fever is usually nothing to worry about when:
- They are drinking, playing and responsive between the peaks. A fever goes up and down, and a child who perks up when it comes down is reassuring.
- It settles with time, usually within three days.
- It came on in the day or two after a vaccination. That is common and expected.
One thing that does not cause a fever: teething. Teething can make a baby warm and miserable, but it does not push the temperature to 38°C. If it gets there, look for another reason.
Looking after them at home
- Fluids first. A feverish child loses more water than usual, and dehydration is the thing that most often turns a simple fever into a problem. Offer drinks little and often. If you are breastfeeding, keep feeding as normal, and offer more often. Wet nappies are your gauge: fewer than usual means they need more.
- Don’t worry about food. Appetite goes with a fever and comes back with recovery. Offer what they will take and don’t push for a normal amount.
- Normal clothing, normal room. Don’t strip them down and don’t wrap them up. Sponging with tepid water does not help, makes them shiver, and is no longer recommended.
- Check on them regularly, including overnight. You are looking for the signs below, not the number.
- Keep them home from nursery, daycare or school until the fever has gone.
Fever medicine
Paracetamol (acetaminophen) or ibuprofen bring the temperature down for a while and make a child more comfortable. That is what they are for. Treat the child, not the number. A child with a fever who is settled and drinking does not need medicine. A child who is miserable does, whatever the reading.
- Give one, not both together. If they are still distressed before the next dose of the first is due, you can give the other. Don’t alternate as a routine.
- Follow the dose and the gap between doses on the pack for your child’s age and weight. Write down what you gave and when. At 3am, nobody remembers.
- No ibuprofen under 3 months or under 5 kg, in chickenpox, or if the child is dehydrated and not drinking.
- Fever medicine does not prevent febrile seizures. Don’t give it for that reason.
Never give aspirin to a child or teenager. It is linked to Reye’s syndrome, a rare but serious illness. Check the label of anything you did not buy specifically for children.
Red flags: get help now
Call your emergency number or go straight to an emergency department if a child with a fever has any of these:
- A rash that does not fade when you press a glass against it. Press the side of a clear glass firmly on the spots. If you can still see them through the glass, seek help immediately.
- Difficulty breathing: fast or laboured breathing, grunting, the skin sucking in between the ribs, or blue lips.
- Hard to wake, unusually drowsy, or unresponsive.
- A seizure, especially the first one.
- A stiff neck, a dislike of bright light, or a bulging soft spot on a baby’s head.
- Cold hands and feet with pale, blue or mottled skin.
See a doctor the same day, or as soon as you can, if:
- The child is under 3 months with any fever at all.
- The fever is above 40°C (104°F).
- The fever has lasted more than 3 days, and at 5 days they need to be seen whatever else is happening.
- They are not perking up between peaks: persistently floppy, listless, or persistently irritable and impossible to comfort.
- Signs of dehydration: far fewer wet nappies or trips to the toilet, dry mouth, no tears when crying, sunken eyes, or a sunken soft spot in a baby.
- They are refusing fluids.
- You have recently travelled abroad, particularly to a country where malaria occurs.
- You are worried. “More unwell than they have ever been” is a valid reason on its own. Parents are good at this. Trust it.
Febrile seizures
Some children between about 6 months and 5 years have a seizure when their temperature rises. It is one of the most frightening things a parent can watch, and it is almost always harmless. Most last a minute or two and the child recovers fully.
If it happens: lie them on their side on a safe surface, move anything they could hit, don’t hold them still, put nothing in their mouth, and note the time it starts. Call your emergency number if it lasts more than 5 minutes, if it is their first one, if a second one happens in the same illness, or if they stay drowsy for more than an hour afterwards. Fever medicine does not prevent them.
What is usually behind it
Think of the common causes before the rare ones. By a wide margin, the usual cause is a viral cold or other upper respiratory infection. After that: ear infections, tonsillitis, chickenpox, roseola (a few days of high fever, then a rash as it settles) and the short-lived fever after a vaccine. A urinary infection is worth thinking about when there is a fever with no obvious reason for it, and a doctor can test for it.
Antibiotics do nothing for viral infections, which means most childhood fevers need none. Seeing a doctor is about ruling out the few that do.
Common questions
Can teething cause a fever?
Not a true one. Teething can make a baby warm, grizzly and dribbly, but it does not push the temperature to 38°C or above. A real fever in a teething baby has another cause, and it is worth looking for it.
Is a fever after vaccination normal?
Yes. A mild fever in the day or two after a vaccine is common and expected, and it settles on its own. Treat it like any other fever: watch how the child is, offer fluids, and give medicine only if they are uncomfortable. A baby under 3 months with a fever still needs to be seen, even after vaccines.
Can I alternate paracetamol and ibuprofen?
Start with one. Don’t give both together. If the child is still distressed before the next dose of the first is due, you can give the other, keeping to the dose and gap on each pack. Alternating every few hours as a routine is not needed and makes dosing mistakes more likely.
Will medicine stop a febrile seizure?
No. Fever medicines don’t prevent febrile seizures, so there is no reason to give them for that. Give them for comfort, and only when the child is uncomfortable.
Doodlebug keeps the fever diary
Log each temperature and each dose in two taps. Doodlebug shows when the next dose is due, plots the readings so you can see whether it’s settling, and gives you the timeline to show the doctor instead of a memory of the night. It’s launching on the App Store now.
Tell me when it’s liveSources
- National Institute for Health and Care Excellence, Fever in under 5s: assessment and initial management (NG143).
- NHS, High temperature (fever) in children.
- NHS, Febrile seizures.
- American Academy of Pediatrics, Fever: When to Call the Pediatrician.
Doodlebug is a tracking app, not a medical service. This page is general information drawn from published guidance and is not advice about your child. Doses, age limits and the name of your emergency number vary by country: follow the pack and your own doctor. If you are worried about your child, get medical help.