When Is It a Fever? Medical Experts Break It Down

Adults feeling under the weather and parents anxious about their children’s health might have misconceptions about what truly constitutes a fever.
The answer isn’t as straightforward as many assume and hinges on various factors, medical professionals explain. Here’s a breakdown of what those thermometer readings really mean:
What’s a Normal Body Temperature?
We often hear that 98.6 degrees Fahrenheit is the standard body temperature. However, there’s a spectrum of temperatures deemed normal, doctors point out. For most, it ranges between 96 and 99 degrees, according to Dr. Amy Horwitz, a family medicine physician at the Cleveland Clinic.
Body temperatures also vary throughout the day, and it’s not necessarily indicative of a fever, Horwitz noted. Factors like your environment, the time of day, or recent physical activity can influence it.
Body temperatures are typically lowest in the morning, the Cleveland Clinic states.
For women, normal body temperature can fluctuate based on their menstrual cycle, with a slight rise post-ovulation.
What Constitutes a Fever?
A fever signifies that your “body’s overall thermal regulation is elevated,” Dr. Angela Mattke, a pediatrician with the Mayo Clinic, explained. It’s often a reaction to your body combating some form of infection.
“People think fevers are bad, but they’re not necessarily something we need to always suppress,” Mattke emphasized.
Alongside a heightened temperature, those with fevers might experience a reduced appetite or altered mental state, Dr. Baruch S. Fertel, MD MPA and emergency physician at NewYork-Presbyterian/Columbia University Irving Medical Center, mentioned.
You may also like: Foods to Ease a Hangover: Post-Party Recovery Tips
Symptoms accompanying a fever can also include sweating, chills, muscle aches, headaches, fatigue, and overall weakness, Horwitz added.
What’s considered a Fever in Adults?
The Centers for Disease Control and Prevention (CDC) defines a fever as a measured temperature of 100.4 degrees Fahrenheit or above.
While some might consider anything above 101 degrees Fahrenheit as a fever, the 100.4 benchmark is widely accepted, Fertel said.
What’s Considered a Fever in Children?
The same 100.4 degrees Fahrenheit threshold applies to children. However, extra caution is advised for infants, doctors stress.
“We’re particularly concerned about infants under 3 months due to their underdeveloped immune systems,” Horwitz highlighted.
While fevers in newborns are critical, parents of older children shouldn’t fixate on numbers, Mattke advised.
“It’s not about the exact number, but how your child behaves,” Mattke said. “Parents often get hung up on the numbers, overlooking the child’s behavior.”
Best Method to Measure Temperature?
For infants, rectal temperatures are recommended as they offer the most accurate assessment, doctors suggest.
For older children, measurements can be taken orally, or via the ear or armpit. Consistency in the method helps track temperature variations, Mattke advised.
“I wouldn’t alternate between methods,” Mattke said. “Choose one and stick with it.”
What’s a Low-Grade Fever?
“Low-grade fever” is a term frequently used by parents, but there’s no specific number tied to it, and many doctors don’t employ this term.
Typically, it refers to temperatures above 98.6 degrees Fahrenheit but below 100.4.
Does a Fever Always Indicate Illness?
Individuals can have fevers without being ill. For instance, some might develop a fever post-vaccination, Horwitz mentioned.
“This is a standard and anticipated response to vaccination, signaling the body’s defense mechanism for future protection,” Horwitz explained. “Though less common, patients with autoimmune conditions or cancer might also experience fevers. Dehydration can also induce a fever.”
How to Manage a Fever at Home?
Doctors recommend rest, hydration, and baths to manage a fever at home. Over-the-counter medications like acetaminophen or ibuprofen can also be taken. Parents should adhere to weight-based dosing for children and always consult a doctor with any concerns.
When to Seek Medical Attention?
For infants younger than 3 months, immediate medical attention is crucial if the temperature exceeds 100.4 degrees, Horwitz advised. For children over 3 months, medical care is essential if the child appears irritable, lethargic, or extremely uncomfortable.
“In older, vaccinated kids, a fever doesn’t necessarily warrant an emergency room visit. But if your child’s behavior is off, we definitely want to see them,” Mattke emphasized.
Adults should seek medical help if, along with a fever, they experience severe headaches, a stiff neck, light sensitivity, confusion, chest pain, shortness of breath, or intense abdominal pain, Horwitz said.
Immunosuppressed individuals should contact a doctor if they have a fever, Fertel added. If a fever persists for three days, it’s also advisable to call a doctor.
With information from CBS News