Fever is an elevation in the body’s temperature.
Noninfectious conditions or scenarios like inflammatory diseases or medication reactions can also cause a fever.
John Fedele / Getty Images
What Is Considered a Normal Body Temperature?
John Fedele / Getty Images
To understand fever, it’s important first to understand what a normal body temperature is.
Body temperature is naturally at its lowest in the early morning and highest in the late afternoon.
Thehypothalamusis a small gland in the brain that controls the body’s temperature, like a thermostat.
Forehead thermometers may be used for all ages.
Axillary and tympanic temperatures are not recommended, as they are unreliable in young children.
Low-Grade Fever Temperature Range
A low-grade fever generally indicates a body temperature that is slightly above normal.
High Fever Temperature Range
A high fever indicates a body temperature that is possibly serious or dangerous.
A high fever inolder children and adultsis a temperature of 102.4 F or greater.
These can include malaise (general feeling of being unwell), headache, and muscle aches.
This is why it is important to read the medication label carefully when giving these medications.
Information on the label can help you determine the correctdose and frequencybased on your child’s weight.
Cooling therapies are not recommended in babies or children with a fever-related illness.
Causes of Fever
There are multiple potential causes of fever.
Viral Infections are the most common cause.
Fever is a response to something in the body, usually a viral infection like the flu or COVID-19.
Most cases of fever are due to viral infections.
Merck Manual Professional Version.
Speaker SL, Pfoh ER, Pappas MA, Hu B, Rothberg MB.Oral temperature of noninfected hospitalized patients.JAMA.
2021;325(18):1899-1901. doi:10.1001/jama.2021.1541
InformedHealth.org.Overview: fever in children.
Ward MA.Fever in infants and children.
In:UpToDate, Edwards MS (Ed), UpToDate, Waltham, MA.
American Academy of Pediatrics.How to take your child’s temperature.
2021;16(4):e0249788.
doi:10.1371/journal.pone.0249788
KidsHealth.Fever (high temperature) in kids.
Suwanwongse K, Shabarek N.Hyperpyrexia in patients with COVID-19.J Med Virol.
2016;6(2):98-101. doi:10.1089/ther.2016.0004
Harvard Health Publishing.Heat stroke (hyperthermia).
2022 Apr 15;10:816136. doi:10.3389/fped.2022.816136
Bush LM.Fever in adults.
Merck Manual Consumer Version.
National Institute of Diabetes and Digestive and Kidney Diseases.Clinical and research information on drug-induced liver injury: acetaminophen.
DailyMed.Label: ibuprofen tablet.
In:UpToDate, Spelman D (Ed), UpToDate, Waltham, MA.
Centers for Disease Control and Prevention.Preventing the spread of respiratory viruses when you’re sick.
El-Radhi AS.Fever in common infectious diseases.Clinical Manual of Fever in Children.
