I’m delighted to welcome guest Cara Barone, MD, FAAP to My Two Hats this week. Dr. Barone is a pediatrician and mother of two. She did her pediatric residency in the Boston Combined Pediatric Program and a fellowship in Pediatric Emergency Medicine at Children’s Hospital Boston. She happily practices general pediatrics at the Palo Alto Medical Foundation in the Palo Alto, CA division. Dr. Barone has written a great post about fever. Please read on to learn more from her about this very common child health concern.

Every day in clinic I talk about fevers, fever-reducing medicines, and taking temperatures. This parental concern has been an absolute mainstay throughout my pediatric career and transcends all age groups in pediatric medicine.

The first and most important thing is to understand what causes a fever. Fever is a chemical reaction within the body and most commonly occurs in response to fighting an infection. Our bodies elevate our core temperature through all kinds of inflammatory mediators (chemicals) in an effort to stop infectious organisms in our bodies. The most common sources of infection in children are viruses. Young children have, on average, 7 to 10 discrete viral illnesses per year–especially if they are in daycare or preschool. Bacteria also can cause infection in children. Both types of infections, viral and bacterial, can (and will) cause fevers. Fever is a healthy sign the body is working properly to fight and overcome an infection.

Fevers are most concerning in young children, especially infants less than 3 months old. This is because their immune systems are developing and leaves them at risk for more severe infections. In preschool age children and beyond, we pediatricians generally don’t worry too much about fevers unless they last for more than 3 days, cause significant irritability, or are accompanied by localized symptoms (examples–bad sore throat, pain with urination, worsening cough, or ear pain).

It is important for parents to know how to take a temperature correctly. In infants and children less than 1 year of age, it is important to feel comfortable taking a rectal temperature in your child. This is the most accurate method of taking a young child’s temperature. New parents are often frightened to take a rectal temperature, but they should feel reassured they will not hurt their child by doing so, nor will it hurt their child to have their temperature taken rectally. It is really quite simple: lubricate the digital thermometer with petroleum jelly and insert the silver tip of the thermometer into the child’s rectum about 1/4 – 1/2 of an inch. Healthy Children has a nice illustration here. For parents who prefer to watch a video demonstration, this is a good one.

In infants less than 2 months of age, a temperature of concern is anything greater than 100.4 Fahrenheit (F) or less than 96 degrees F rectally. In children older than 3 months of age, a notable fever is greater than 101.5 F.

For children over 1 year of age, the best and most accurate methods of taking a temperature are either with an oral digital thermometer or a tympanic (ear) thermometer. Tympanic thermometers are great for the toddler and young child age. Their only limitation in accuracy is if your child has a lot of earwax. Further information on these methods can also be found at Healthy Children.

Pacifier thermometers and temporal artery thermometers have not yet been found to be accurate in studies and are not recommended. Feeling a child’s head and estimating a temperature is also not accurate.

Many children lose their appetite when they have a febrile illness. As pediatricians, we reassure parents about this because we know kids’ appetites will return before long as they start feeling better. However, we do worry when children are not drinking well when they have a fever. Children with fevers should frequently be offered small amounts of liquids and if they are not drinking well and urinating well you should alert your pediatrician’s office.

Fever-reducing medicines are not needed for low-grade fevers (99-101) unless your child seems uncomfortable or is not drinking well. Once a child’s fever rises above 101.5, they generally feel miserable and fever-reducing medicines will help them to feel better.

You should call your pediatricians’ office if:

1) Your infant less than 2 months old has a fever > 100.4 F or < 96 F rectally
2) Your infant greater than 2 months old has a fever > 101.5 and is fussy, irritable, not drinking well, or isn’t making normal amount of wet diapers
3) Your preschooler or older child has a temperature > 101.5 for more than 3 days
4) Your preschooler or older child has a temperature > 101.5 with concerning localizing symptoms such as terrible sore throat, ear pain, abdominal pain, pain with urination or other localizing symptoms
5) Your child has had a viral illness and develops a fever a few days into the illness
6) Your child seems very listless, uncomfortable, or irritable with a fever–especially if you’ve already given him/her a fever-reducing medicine.

As a parent, you will most certainly experience fevers with your children. It is important to know what a fever means in the body, how to correctly take your child’s temperature, how to correctly give fever-reducing medicines, and when you should be concerned as a parent.

Please also see the second post in this series, Medicines for Fever: When and How to Use Them.