Fever Facts for Kids 🌡️
Fevers are a topic that are very important to discuss during well-child checks. It can be scary when your child gets a fever for the first time, and myths about fevers are rampant amongst both parents and doctors. If your child is <3mths and has a fever, this is an Emergency Room visit!
A fever is not an illness, it is a response or reaction the body makes towards something (like an infection, medication, or injury). We don’t care about treating the fever itself, but rather, treating the cause of the fever and ensuring hydration status throughout the temperature rise.
You’ll get different temperature measurements depending on how you take the temperature (ear, mouth, rectum (bumhole), armpit, forehead). Mouth temperature is about 0.6°C lower than the core temperature and is recommended for kids who can do it properly (15 minutes away from fluid intake). For younger children infrared ear thermometers are generally most convenient with reasonable accuracy. Rectal is the most accurate option in a situation where it’s absolutely necessary to know the core temperature (not usually the case at home!).
The body temperature actually varies throughout the day with the lowest temperatures in the morning and up to 1°C higher in the afternoon (this variation happens during a fever too!). It can be helpful to know your child’s baseline with your home thermometer so you have something to compare to.
Some facts that you may not know (for an otherwise healthy child):
A fever in kids 3mths-3 years old is generally considered to be a rectal or ear temperature of >38°C, or mouth temp greater than 37.8°C. I would argue (and some literature agrees) that any 0.6-1°C increase over their baseline (keeping in mind the time of day) could be considered a fever.
In older kids/adults a fever is defined as oral temperature >37.8°C (again depending on baseline)
A fever is part of the inflammatory response and can be helpful to slow the growth and reproduction of bacteria and viruses and support the immune function as long as the temperature stays below 40°C.
Fevers do cause discomfort and put extra demand on the heart and lungs, for an otherwise healthy child these stresses are of minimal consequence.
How sick a child looks (drowsiness, not playing, not smiling, not drinking…) is more important than the number on the thermometer. For kids the temperature reading does not seem to indicate the severity of illness, where it often does for adults. Some kids fever with even the mildest cold.
The primary goal of an antipyretic (i.e. tylenol or advil) is to decrease a child’s discomfort. This can be beneficial if they’re having difficulty sleeping or hydrating (which is extremely important), but should not be used solely because their temperature is elevated. The way their temperature responds to an antipyretic agent doesn’t help to distinguish whether they’re fighting a viral or bacterial infection.
The latest evidence discourages combining/alternating antipyretic agents as the impact does not seem to be clinically significant, there is possibility for dosing confusion, and there is little information about the safety of this approach.
There’s no evidence to suggest that fever >40°C on it’s own is associated with increased risk of adverse outcome (i.e.) brain damage. That said, a fever >40°C should absolutely be evaluated to understand the cause and ensure hydration status.
While fevers can cause febrile seizures in susceptible children, there is no evidence that using antipyretics decreases that risk.
It’s always important to have a discussion with your healthcare provider about fevers. Especially preventatively!
If your child has underlying health concerns, a fever might need to be treated differently - have this conversation with your healthcare provider!
I often work with patients at the start of cold/flu season to outline when they need further support and evaluation (i.e. when to choose the ER, walk-in clinic, or home care). We also discuss pieces to put in place at home to promote hydration and support the body's ability to fight the underlying cause of the fever.