Fever in Children

A fever is a natural reaction of the body to an illness, such as infections from viruses or bacteria. In most cases, the fever itself isn't harmful. It actually helps the body fight infections. A fever does not need to be treated unless your child is uncomfortable and looks or acts sick. How your child looks and feels are often more important than the level of the fever.

If your child has a fever, check his or her temperature as needed. Don't use a glass thermometer that contains mercury. It can be dangerous if the glass breaks and the mercury spills out. Always use a digital thermometer when checking your child’s temperature. The way you use it will depend on your child's age. Ask your child’s healthcare provider for more information about how to use a thermometer on your child. General guidelines are:

  • The American Academy of Pediatrics advises that rectal temperatures are most accurate for children younger than 3 years, especially babies up to 3 months of age. Accuracy is very important because babies must be seen right away by a healthcare provider if they have a fever. Be sure to use a rectal thermometer correctly. A rectal thermometer may accidentally poke a hole in (perforate) the rectum. It may also pass on germs from the stool. Always follow the product maker’s directions for proper use. If you don’t feel comfortable taking a rectal temperature, use another method. When you talk with your child’s healthcare provider, tell them which method you used to take your child’s temperature.

  • For toddlers and younger children, a temperature may be taken under the armpit (axillary), but this method is the least accurate.

  • For children old enough to hold a thermometer in the mouth (usually around 4 or 5 years of age), take the temperature in the mouth (oral).

  • For children age 6 months and older, you can use an ear (tympanic) thermometer.

  • A forehead (temporal artery) thermometer may be used in babies and children of any age. This is a better way to screen for fever than an armpit temperature.

Hands holding digital tympanic thermometer in child's ear and pressing power button.
Ear (typmpanic) thermometer.

Comfort care for fevers

If your child has a fever, here are some things you can do to help them feel better:

  • Give fluids to replace those lost through sweating with fever. Water is best, but low-sodium broths or soups, diluted fruit juice, or frozen juice bars can be used for older children. Talk with your healthcare provider about a plan. For an infant, breastmilk or formula is fine and all that is usually needed.

  • If your child has discomfort from the fever, check with your healthcare provider to see if you can use ibuprofen or acetaminophen to help reduce the fever. The correct dose for these medicines depends on your child's weight. Don’t use ibuprofen in children younger than 6 months old. Never give aspirin to a child under age 18. It could cause a rare but serious condition called Reye syndrome.

  • Make sure your child gets lots of rest.

  • Dress your child lightly and change clothes often if they sweat a lot. Use only enough covers on the bed for your child to be comfortable.

Facts about fevers

Fever facts include the following:

  • Exercise, eating, excitement, and hot or cold drinks can all affect your child’s temperature.

  • A child’s reaction to fever can vary. Your child may feel fine with a high fever, or feel miserable with a slight fever.

  • If your child is active and alert, and is eating and drinking, you don't need to give fever medicine.

  • Temperatures are naturally lower between midnight and early morning and higher between late afternoon and early evening.

When to call your child's healthcare provider

Call the healthcare provider’s office if your otherwise healthy child has any of the signs or symptoms below:

  • Fever (see Fever and children, below)

  • A seizure caused by the fever

  • Rapid breathing or shortness of breath

  • A stiff neck or headache

  • Trouble swallowing

  • Signs of dehydration. These include severe thirst, dark yellow urine, infrequent urination, dull or sunken eyes, dry skin, and dry or cracked lips

  • Your child still doesn’t look right to you, even after taking a nonaspirin pain reliever

Fever and children

Use a digital thermometer to check your child’s temperature. Don’t use a mercury thermometer. There are different kinds and uses of digital thermometers. They include:

  • Rectal. For children younger than 3 years, a rectal temperature is the most accurate.

  • Forehead (temporal). This works for children age 3 months and older. If a child under 3 months old has signs of illness, this can be used for a first pass. The provider may want to confirm with a rectal temperature.

  • Ear (tympanic). Ear temperatures are accurate after 6 months of age, but not before.

  • Armpit (axillary). This is the least reliable but may be used for a first pass to check a child of any age with signs of illness. The provider may want to confirm with a rectal temperature.

  • Mouth (oral). Don’t use a thermometer in your child’s mouth until they are at least 4 years old.

Use the rectal thermometer with care. Follow the product maker’s directions for correct use. Insert it gently. Label it and make sure it’s not used in the mouth. It may pass on germs from the stool. If you don’t feel OK using a rectal thermometer, ask the healthcare provider what type to use instead. When you talk with any healthcare provider about your child’s fever, tell them which type you used.

Below are guidelines to know if your young child has a fever. Your child’s healthcare provider may give you different numbers for your child. Follow your provider’s specific instructions.

Fever readings for a baby under 3 months old:

  • First, ask your child’s healthcare provider how you should take the temperature.

  • Rectal or forehead: 100.4°F (38°C) or higher

  • Armpit: 99°F (37.2°C) or higher

Fever readings for a child age 3 months to 36 months (3 years):

  • Rectal, forehead, or ear: 102°F (38.9°C) or higher

  • Armpit: 101°F (38.3°C) or higher

Call the healthcare provider in these cases:

  • Repeated temperature of 104°F (40°C) or higher in a child of any age

  • Fever of 100.4° F (38° C) or higher in baby younger than 3 months

  • Fever that lasts more than 24 hours in a child under age 2

  • Fever that lasts for 3 days in a child age 2 or older

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