What Temperature Is Considered a Fever in Adults?

It’s one of the most common COVID-19 symptoms—here’s the temperature range you need to know.

Familiar to most, the concept of fevers is not alien: Individuals have encountered elevated body temperatures on various occasions, often linked to infections caused by bacteria or viruses, such as the well-known influenza. However, since the emergence of COVID-19, there has been notable uncertainty surrounding the interpretation of temperature readings and the appropriate level of concern they should invoke.

COVID-19 manifests through a range of symptoms, encompassing issues like headaches, sore throats, and nasal congestion, among others. A frequently observed symptom is fever. According to a comprehensive systematic review and meta-analysis from April 2021, which examined 17,515 COVID-19 patients, it was found that 79.43% of adults and 45.86% of children exhibited fever in conjunction with their COVID-19 diagnosis. Notably, within the group of adults experiencing fever, 14.71% of cases reported high-grade fever, defined as temperatures reaching 103 degrees Fahrenheit or higher.

It is crucial to underscore that not every instance of COVID-19 leads to a fever, and conversely, not all fever cases indicate a COVID-19 infection. Nonetheless, fever remains a prevalent and widely recognized symptom associated with the virus.

How Do You Treat a Fever?

As detailed by the MedlinePlus resource from the US National Library of Medicine, a fever, also known as pyrexia, denotes a body temperature exceeding the normal range. This baseline body temperature varies among individuals but generally hovers around 98.6 degrees Fahrenheit; intriguingly, one study suggests this average has diminished to 97.9°F over the past two centuries.

For the Centers for Disease Control and Prevention (CDC), a temperature reading of 100.4 degrees Fahrenheit is recognized as indicative of a fever. While an actual temperature measurement remains the foremost diagnostic criterion, the CDC acknowledges additional signs of fever, including a person feeling notably warm to the touch, self-reporting previous instances of feverishness often accompanied by chills, or displaying a flushed or glassy-eyed appearance.

Jill Grimes, MD, FAAFP, a board-certified family physician practicing at UT Austin’s Student Health Services, elaborates that fevers encompass distinct ranges and degrees of severity. A low-grade fever, for instance, characterizes an elevated body temperature that surpasses the norm but does not breach or only slightly surpasses the fever threshold. Dr. Grimes notes that this range generally falls between 99 to 100.9 degrees, emphasizing that it does not qualify as a “true fever.”

“In a general context, when physicians encounter a measured temperature exceeding 101 degrees, it prompts our attention as we begin to investigate the potential presence of an infection,” Dr. Grimes elucidates. According to the American Academy of Family Physicians (AAFP), temperatures reaching 103 degrees or higher are designated as high fevers, possibly indicating a perilous infection necessitating prompt medical intervention.

Why Do Fevers Happen—and What Do They Feel Like?

It’s crucial to emphasize that a fever doesn’t constitute an independent ailment; rather, it serves as an indicator that your body is engaged in combat against an illness or infection, as highlighted by MedlinePlus. This informative resource elucidates that the viruses and bacteria responsible for infections can thrive within the normal temperature range of the human body. A fever emerges as a response to thwart these pathogens by creating an inhospitable environment. Moreover, fevers trigger the activation of the body’s immune system, augmenting efforts to eliminate the invading agents.

Regarding the sensation of having a fever, the experience is contingent upon the degree of temperature elevation, as explained by Matthew Mintz, MD, FACP, an accomplished internist practicing in Bethesda, Maryland. Dr. Mintz shared with Health that sensations of warmth, flushing, coldness, chills, and overall bodily discomfort are common manifestations, albeit not all individuals may encounter each symptom. He further noted that fevers can exhibit cyclical patterns, rising and falling, with instances of sweating often accompanying a fever’s decline.

The complexity of fevers is magnified, especially concerning COVID-19. Unlike other viruses such as influenza, which typically lead to prompt symptom onset, there exists a lag between the entry of the COVID-19 virus into the body and the emergence of symptoms like fever. Dr. Mintz elaborated, “Upon contracting coronavirus, symptoms, including fever, may manifest within the initial two weeks, typically averaging between four to six days.” Consequently, individuals could be carriers of the virus for several days, inadvertently spreading infection without exhibiting signs of illness. Dr. Mintz highlighted that in certain cases, fever might not emerge as an initial symptom—or not appear at all. Instead, patients could experience a cough or other symptoms before developing a fever, or they might remain entirely asymptomatic.

What Exactly Counts as a Fever?

In the majority of cases, a slight elevation in body temperature does not warrant immediate alarm. Dr. Grimes underscores, “Ordinarily, fevers on their own do not necessitate urgent medical attention for adults unless they persist beyond a day or two or surge above 103 degrees.”

MedlinePlus advises those with a fever to prioritize rest and hydration, achieved through water consumption or intake of items like gelatin, ice pops, or soup. While mild fevers typically do not require medication, if a fever is coupled with intense headache, a stiff neck, or breathlessness, a medical consultation becomes imperative. For fevers surpassing 102 degrees Fahrenheit, acetaminophen (Tylenol), ibuprofen (Advil), or aspirin can be administered to alleviate the fever. However, if the fever remains unresponsive to medication or escalates beyond 103 degrees Fahrenheit, medical attention should be sought.

Turning attention to COVID-19 specifically, relying solely on temperature readings will not ascertain infection. Yet, if accompanied by other typical symptoms (such as dry cough, fatigue, gastrointestinal disturbances) or more severe indications (like breathing difficulties, chest pressure, confusion, inability to remain awake, bluish or grayish hue in the skin, lips, or nails), it is imperative to reach out to a healthcare professional and arrange for testing. If there are concerns about a potential COVID-19 diagnosis, prompt self-isolation is advised. Subsequently, if diagnosed with COVID-19, strict adherence to the doctor’s directives is vital. This encompasses extended self-isolation, autonomous management of symptoms, and prompt medical attention if symptoms or overall condition deteriorate.