When Is a Fever Too High for a Child? Essential Guidelines

Normal Body Temperature Ranges for Children

Healthy children have a body temperature between 97.7°F (36.5°C) and 99.5°F (37.5°C). A child’s temperature changes throughout the day but is usually higher by about 0.5°C in the evening compared to the morning.

Overview of Fever in Children

A fever is a temporary elevation in body temperature. It is an immune response and is most commonly caused by infections.

Many healthcare providers consider body temperatures at or above 99.5°F (37.5°C) as elevated temperature or fever.

In children, the body temperature that is called fever depends on the child’s age. It is considered a fever if the temperature is at or above 100.4°F (38.0°C) in babies under 3 months of age and at or above 101.3°F (38.5°C) in older children.

Fevers can be uncomfortable for children and adults, but they usually go away in a few days and aren’t concerning. However, high fevers should be evaluated by a healthcare provider. In infants, even a low grade fever should be evaluated as it can be a sign of a serious infection.

Measurement Methods for a Child’s Temperature

You can take your child's temperature in the following ways:

Oral (by placing a thermometer in the mouth and under the tongue)
Axillary (in the armpit)
Tympanic (in the ear)
Skin (using a temporal artery thermometer on the forehead)
Rectal temperature (by placing a thermometer in the child’s rectum)

A rectal temperature measurement gives the most accurate reading. However, an oral temperature may be more convenient in children above 4-5 years of age and is equally accurate when done properly. Temperature measurements in the armpit, on the forehead, and in the ear are the least accurate but can be used as an initial test for fever.

Digital thermometers are preferred because glass thermometers contain mercury, which is toxic.

Fever Thresholds by Age Group and Best Ways to Measure Temperature

The best way to take your child’s temperature depends on how old the child is:

Newborn to 3 months: Rectal using a digital thermometer.
6 months and above: Ear thermometer.
3 months to 4 years: Rectal, armpit, or forehead thermometer.
4-5 years and above: Oral temperature using a digital thermometer.

Age	Body's temperature considered a fever	Method of measuring temperature
0-2 years	100.4F (38C)	Rectal
0-2 years	99F (37.2C)	Armpit
2-5 years	100.4F (38C)	Rectal or Ear
2-5 years	99F (37.2C)	Armpit
5+ years	100.4F (38C)	Ear
5+ years	100F (37.7C)	Mouth
5+ years	99F (37.2C)	Armpit

Causes of Fever in Children

Infections

Bacterial and viral infections are the most common causes of fever in children, for example, upper respiratory tract infections (colds and cough), flu, ear infections, roseola, tonsillitis, urinary tract infections, and childhood illnesses such as chickenpox and whooping cough. Read about other common respiratory illnesses in children.

Fever is a healthy sign. It tells you that your child’s body is fighting the infection. The immune system prevents viruses and bacteria from multiplying by elevating the core temperature. Therefore, mild fever is not a worrisome sign in children with infections. However, in infants under 3 months old, any fever is concerning. This is because their immune systems are still developing and a fever can indicate a serious infection.

Other Medical Conditions

The following medical conditions can also cause fever in children:

Heat stroke
Blood transfusions
Autoimmune diseases
Brain disorders
Certain cancers
Some medications

Vaccinations

It’s common for children to develop a fever after vaccinations. This is a normal immune response. The child’s fever after vaccination is evidence that their immune system is responding to the vaccine and building immunity. Learn about the vaccine schedule for children.

Recognizing Dangerous Fevers

What temperature is dangerously high for a child?

Fever is too high in children:

At 100.4 °F (38.0°C) or a higher temperature in an infant younger than 3 months old.
At 102.2°F (39°C) or a higher temperature in an older child.

You should call your doctor if your child has a fever. Go to the emergency room and get immediate medical attention if your child has a fever of 104.0°F (40°C) or higher. Find out “When Should You Go To The Hospital For A Fever?”

When to Worry About a Child’s Fever

You should worry about your child’s fever in the following circumstances:

Fever above 102.2°F (39°C) in children of any age.
Fever above 100.4 °F (38.0°C) in babies.
High temperature for 5 days or longer.
Fever for 3 days or longer without any obvious infection.
Fever that comes and goes.
A febrile seizure.
Fever after a trip overseas.

You can treat kids’ fevers at home if the fever is under 102.2°F and your child has an infection that can explain it. However, even low grade fevers should be evaluated by the pediatrician in infants younger than 3 months old.

Other Symptoms to Watch For

Parents and caregivers should call the child’s physician or take them to the emergency department if the child shows the following symptoms:

Excessive sweating
Dry, hot skin
Skin rash
Very pale or very red face
Fast, slow, noisy, or strained breathing
Sneezing, runny nose, cough, sore throat, hoarseness
Vomiting, diarrhea, refusing to eat or feed
Pain in any part of the body
Signs of dehydration (dry nappies, no tears when crying, sunken eyes)
Headache or stiff neck
Irritability, crankiness, lack of energy
Restlessness
Confusion
Worsening condition

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How to Reduce Fever in Child Naturally

In most cases, fever in children goes away in 2-3 days. Here are some tips on managing your child’s fever at home:

Avoid a hot environment or clothing that’s too warm. Don’t cover your child with too many blankets so that your child feels warm and heat cannot escape.
Give your child plenty of rest and cool, clear fluids to keep them hydrated. Water and Pedialyte are preferred, but fruit juices, sports drinks, and popsicles can also be given.
Check for early signs of dehydration if your child is sick, such as a dry mouth, lack of tears when crying, and decreased urine output. Infants under 6 months of age should have 6-8 wet diapers a day and older children should urinate at least 3 times in 24 hours.
Give the child a lukewarm bath, but not a cold bath.
Place cold washcloths on the forehead and wrists.
Keep your child home from daycare or school until they have been fever-free for at least 24 hours without taking fever-reducing medication.

Fever Medications and Dosages in Children

Two of the most common medications for fever in children are acetaminophen (Tylenol) and ibuprofen (Motrin).

Acetaminophen is safe for children of all ages. Ibuprofen should not be given to babies under 6 months of age.
You can alternate acetaminophen (Tylenol) and ibuprofen (Motrin, Advil) to keep your child’s fever down.
Read the package instructions carefully and make sure you give the doses appropriate for your child’s age or body weight.
Many common over-the-counter fever, cough, and cold remedies contain acetaminophen and ibuprofen. Read the package labels carefully to avoid overmedicating by using multiple products with the same ingredients.

Read about 8 Medications Not Approved For Children.

FAQs About Childhood Fevers

Can fever cause a seizure?

Fever can cause a seizure in children between 6 months and 5 years of age. These are called febrile seizures (convulsions) that typically occur with high fever. Children who have had a febrile seizure in the past are more likely to have another one. Seek care in the emergency room if a seizure lasts more than 5 minutes. Most children outgrow febrile seizures. Having a febrile seizure does not mean the child has epilepsy.

Should a child have medication for a fever?

Most fevers don’t need to be treated. Fever medicine in children is only necessary if the child is very uncomfortable. If your child has a fever, treating it will not clear the infection any faster. In fact, fever helps the body fight infection. However, many parents use over-the-counter fever-reducing medication to relieve discomfort associated with fever.

What temperature is too high for a 3-year-old?

A temperature at or above 100.4F (38C) is considered high in a 3-year-old. Call your doctor if your child has this temperature.

When to take a 3-year-old to the hospital for a fever?

You should take a 3-year-old to the hospital for a fever above 102.2°F (39°C). Also call the child’s physician or take them to the hospital if the fever continues for more than 3 days despite fever medicine or is accompanied by other serious symptoms.

How high should you let a child's fever go?

In general, you can let a child’s fever go up to 102.2°F (39°C) (100.4°F or 38°C in babies younger than 3 months) before you call a doctor or seek medical attention.