Fever is an increase in the body’s temperature above normal. Body temperature is usually lowest in the morning and goes up through the day. Each person’s body temperature can be different. It is hard to give an exact temperature for a fever, but most health care providers agree that a fever is a temperature of 100.4˚ Fahrenheit (F) or 38˚ Celsius (C) or higher.
Fevers can show that the body is fighting an infection from a virus or bacteria. It can also happen after getting a vaccine, from getting overheated, or from a very bad sunburn. Many times, the fever does not need to be treated and will go away on its own.
How to Take a Temperature
The type of thermometer used may make a difference.
- To take a temperature, use a digital thermometer. Never use a mercury thermometer.
- Rectal (in baby’s bottom) thermometers are the most accurate.
- Forehead (temporal artery) thermometers are the next best choice if used the right way.
- Oral (mouth) and ear (tympanic) thermometers can be used if done properly. For oral temperatures, wait 30 minutes after drinking something hot or cold. For ear, wait 15 minutes after coming in from the cold.
- Lastly, an axillary (armpit) temperature can be used as a quick check but it is not very accurate.
The best ways to check your child’s temperature depends on their age.
- Under 3 months: rectal or forehead thermometers
- 4 months or older: rectal, forehead, or axillary thermometers
- Older than 6 months: rectal, forehead, ear, or axillary thermometers
- 4 years old or older: oral (mouth), forehead, ear, or axillary thermometers
Be sure to tell your child’s health care provider which method you used.
A fever may not need to be treated unless your child is uncomfortable. Even higher temperatures are not usually dangerous unless they have a long-term illness.
- Dress your child in light clothing. Over dressing them can trap the body’s heat and make the temperature go higher.
- Babies under age 1: Dress them in a sleep sack or wearable blanket. Do not put loose blankets over them.
- Children over age 1: While sleeping, cover them with a sheet or light blanket.
- Give extra fluids.
- Babies under age 1: Continue to give breast milk and formula. They should not be given water. If they are older than 6 months, you can give Pedialyte®.
- Children over age 1: Offer extra liquids to drink, like water, diluted 100% juice, popsicles, or Pedialyte.
- Your child may not want to eat much. Offer soft foods often and in small amounts but do not force them to eat.
- Give sponge baths or let your child soak in a tub. Water should be lukewarm, not too hot or cold. Use a wash cloth to sponge the water over your child’s body (Picture 1).
- Do NOT add alcohol to the water. It can be dangerous.
- Recheck your child’s temperature 15 minutes after the bath. If the temperature is 103˚F (39.4˚C) or is going higher, repeat the sponge bath.
- Over-the-counter medicines can help lower a fever. Read the label on the bottle to know the right dose for your child.
- Acetaminophen (Tylenol®) may be used in all children over 2 months.
- Ibuprofen (Advil®, Motrin®) may be used in children over 6 months.
- Do NOT give aspirin to children (Picture 2). Aspirin has been linked to a disease called Reye’s syndrome, which can be fatal.
When to Call the Health Care Provider
Call your child’s health care provider right away if your child:
- Is younger than 3 months of age and has a temperature of 100.4˚F (38˚C) or higher.
- Is older than 3 months and has a temperature:
- Of 104 ˚F (40 ˚C) or above.
- Above 102˚F (38.9˚C) for more than 2 days or keeps coming back.
- That has been treated to bring it down, but it has not worked.
- At any age, has a fever and:
- Looks very ill, is very fussy, or very drowsy.
- Is not eating or drinking and shows signs of dehydration – dry or sticky mouth, sunken eyes, dark urine, dry diapers, or not urinating.
- Has a stiff neck, bad headache, very sore throat, painful stomach ache, vomiting, or diarrhea.
- Has an unusual rash
- Has been in a very hot place, such as an overheated car.
- Has immune system problems that make them more likely to get sick, such as sickle cell disease or cancer, or takes a medicine that weakens the immune system.
Call 911 or go to the emergency department if your child has trouble breathing, has a seizure, or is hard to wake up.
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HH-I-105 10/75 Revised 2/22 Copyright 1975, Nationwide Children’s Hospital