Fever in Children: When to Worry and What to Do

What counts as a fever in a child

Normal body temperature is about 36.5 to 37.5 °C (97.7 to 99.5 °F) and varies through the day. A fever is 38 °C (100.4 °F) or higher.

Do not use glass mercury thermometers. Feeling the forehead is not reliable.

Why children get fevers

Fever is the immune system raising the body's thermostat to fight infection. Germs reproduce less well at higher temperatures, and immune cells work better. Fever itself does not damage the brain unless it rises above about 42 °C (107.6 °F), which almost never happens from an infection alone. Heatstroke from overheating, such as being left in a hot car, is different and dangerous.

Common causes

• Viral infections: colds, flu, COVID-19, RSV, stomach viruses, hand, foot and mouth disease and many others. These cause most fevers.
• Roseola: 3 to 5 days of high fever in a child aged 6 months to 2 years, followed by a pink rash as the fever goes.
• Ear infections: ear pain, pulling at ears, poor sleep, often after a cold.
• Strep throat: sore throat, fever and swollen glands, usually over age 3.
• Urinary tract infections: may cause fever with no other symptoms in babies and toddlers. Older children have pain on peeing or tummy pain.
• Vaccines: low-grade fever for 1 to 2 days.
• Teething may cause a slight rise in temperature but does not cause a true fever of 38 °C (100.4 °F) or higher.

Serious causes

• Meningitis and sepsis: a sick, drowsy child, a non-fading rash, stiff neck, cold hands and feet with fever, or pale, mottled skin.
• Pneumonia: fever with fast or difficult breathing and cough.
• Kidney infection: high fever, vomiting, back or side pain.
• Kawasaki disease: fever for 5 or more days with red eyes, red cracked lips, rash, swollen hands and feet. Needs treatment to protect the heart.
• Bone or joint infection: fever with a limp or refusing to use a limb.

Fever by age: when to call

Babies under 3 months

Young babies cannot fight infection as well and may show few other signs, so any fever of 38 °C (100.4 °F) or higher needs a same-day medical assessment, often with blood and urine tests. Do not give fever medicine before calling, because it can mask the fever. Also call if a young baby's temperature is below 36 °C (96.8 °F).

3 to 6 months

Call your doctor for a fever of 39 °C (102.2 °F) or higher, or any fever with poor feeding, unusual sleepiness or fewer wet diapers.

6 months to 5 years

Most fevers are viral and can be managed at home if the child is drinking and alert. Call for fever lasting more than 3 days in under-2s, or 5 days at any age, or for any red flag in the triage list.

Older children

Judge by behavior. A child who is playing and drinking between doses of fever medicine is usually fine. Watch for the red flags above and for symptoms pointing to a specific infection.

Febrile seizures

About 2 to 5 percent of children between 6 months and 5 years have a seizure triggered by fever. The child stiffens or shakes, may become unresponsive, and usually recovers within 5 minutes. Febrile seizures are frightening but rarely harmful and do not cause epilepsy in most children. Lay your child on their side on a safe surface, do not put anything in their mouth, and time it. Call 911 for a first seizure, a seizure lasting more than 5 minutes, or difficulty breathing afterward. Fever medicine does not prevent febrile seizures.

How to treat a fever at home

The goal is comfort, not a normal temperature.

• Fluids: offer breast milk, formula or water often. Popsicles and diluted juice help older children. Watch for wet diapers.
• Dress lightly: one light layer and a light blanket. Do not bundle up a feverish child.
• Fever medicine if the child is uncomfortable: - Acetaminophen (paracetamol) from birth (ask a doctor first under 12 weeks). - Ibuprofen from 6 months, if the child is drinking well and not dehydrated. - Dose by your child's weight, using the measuring device that comes with the medicine, and follow the label.
• Never give aspirin to children or teenagers. It is linked to Reye syndrome, a rare but serious liver and brain condition.
• Do not sponge with cold water or alcohol. It causes shivering and discomfort, and alcohol can be absorbed through the skin. A lukewarm bath is fine if it soothes.
• Let them rest, and keep them home from school or daycare until they have been fever-free for 24 hours without medicine.

Alternating acetaminophen and ibuprofen is not usually recommended because it increases dosing errors. Use one; switch only if the first does not help before the next dose is due, and follow your doctor's advice.

How doctors assess a feverish child

A doctor will check temperature, heart rate, breathing rate, oxygen level, hydration, skin color and rash, ears, throat, chest and abdomen, and how alert the child is. NICE uses a "traffic light" system based on color, activity, breathing and hydration to judge risk. Tests may include a urine sample (very important in babies and toddlers with no obvious source), blood tests, a chest X-ray, or a lumbar puncture in young babies or if meningitis is possible.

Frequently asked questions

When should I worry about a child's fever?

Worry about any fever in a baby under 3 months, fever with a non-fading rash, breathing difficulty, stiff neck, seizure, dehydration or a child who is floppy or hard to wake. Also see a doctor if fever lasts over 5 days, or over 3 days in a child under 2.

What temperature is too high for a child?

For babies under 3 months, 38 °C (100.4 °F) is the threshold for urgent assessment. For babies 3 to 6 months, 39 °C (102.2 °F) or higher. In older children, the height of the fever matters less than how sick the child looks and behaves.

How can I bring down my child's fever fast?

Give acetaminophen (paracetamol) or, from 6 months, ibuprofen at the correct weight-based dose, offer fluids and dress your child lightly. Fever usually drops by about 1 to 1.5 °C within an hour. Do not use cold baths or alcohol rubs.

How long does a fever last in children?

Most viral fevers last 2 to 3 days, and many settle within 5 days. Roseola often causes 3 to 5 days of high fever. A fever lasting more than 5 days, or that returns after going away, should be checked by a doctor.

Can teething cause a fever?

Teething can cause a slightly raised temperature, but not a true fever of 38 °C (100.4 °F) or higher. If your teething baby has a real fever, look for another cause, such as an infection, and follow the usual advice for their age.

Should I wake my child to give fever medicine?

No. Sleep helps your child recover, and fever medicine is for comfort. If your child is sleeping peacefully, let them sleep. Do check on them, and wake them if their breathing seems fast or labored or they look very unwell.