5 facts about fevers: Causes, complications & care

The human body is designed to function best within a certain temperature range. The average “normal” body temperature is 98.6 F. 

While many people use the term “fever” loosely, meaning they feel flushed or warmer than usual, the medical criteria for fever is a temperature of 100.4 F or higher.

On average, children get fevers more frequently than adults, and their fevers tend to run higher than what adults experience.

Cold and flu season is generally during the winter months in the U.S., but that doesn’t mean we’re in the clear for the remainder of the year. In addition to these germs, we continue to be exposed to COVID-19 and many other viruses. 

Microbes can result in a variety of symptoms, including fevers. Hence, it’s important to understand the ins and outs of fevers. That’s why we’ve outlined five fever facts to remember when you’re not feeling great — including when to go to urgent care for a fever. 

1. Fevers are regulated by your brain

The hypothalamus, commonly referred to as the body’s “thermostat,” is located in the brain. A fever happens when the hypothalamus shifts the body’s set point to a higher temperature. 

When this happens, you might feel flushed or feverish. Paradoxically, patients also can experience chills when experiencing a fever. That’s because the current body temperature is lower than the new set point. Furthermore, chills and shivering cause rapid muscle contractions that help raise the body’s internal temperature.

2. The most common cause of fevers is infection

Infections are the most common reason why people get fevers. Most microorganisms have a narrow temperature window in which they can survive. Sometimes, this window is as narrow as 2 F.

When your body is infected with a harmful pathogen, your hypothalamus raises the body’s internal temperature to a level at which the pathogen can no longer survive. While it’s a temporary discomfort for you, this higher temperature defeats the pathogen and resolves the infection.

3. Other conditions can cause fevers as well

While infections are the most common source of fevers, other non-infectious conditions can also cause fevers. Certain cancers, autoimmune disorders, medications, and heat-related illnesses can cause fevers.

Patients with prolonged or recurrent fevers should seek medical attention to rule out these non-infectious fever sources since these conditions are often dangerous if left undetected or untreated.

4. Fevers can cause complications

A fever usually indicates a healthy immune system’s appropriate response to the presence of an infection. However, fevers can cause complications in certain situations.

For example, you can quickly become dehydrated from a fever, even if you’re not losing fluid from vomiting or diarrhea. That’s because water evaporates faster off hot surfaces. So, the hotter your skin temperature is, the faster fluid will escape from your body. Febrile patients can also lose fluid from excess sweating.

Small children become dehydrated faster than larger children or adults, so it’s essential to be vigilant of their hydration status. Febrile patients should be encouraged to drink plenty of clear fluids, primarily water. Fever-reducing medication is often helpful in patients with high or prolonged fevers to lower the skin temperature and slow the rate of fluid loss.

Another fever-related complication that children between the ages of 6 months and five years can experience is a seizure. These are called febrile seizures.

Febrile seizures are triggered when the body’s internal temperature rises too rapidly. While febrile seizures usually only last a few minutes and do not indicate any dangerous underlying condition, any child with a fever and a seizure requires immediate medical attention to rule out a more serious diagnosis, including meningitis (an infection and inflammation of the fluid surrounding your brain and spinal cord).

5. Several treatments for fevers are available

The treatment for a fever depends on several factors, including the source of the fever, duration, severity of symptoms, age of the patient, and any underlying conditions.

Most fevers due to viral infections resolve on their own within 96 hours and don’t require any specific treatment. Still, you may benefit from rest, oral hydration, and over-the-counter medications that alleviate pain and help reduce body temperature.

Bacterial infections are often treated with antibiotics, and fungal infections can be treated with antifungal medications. The treatment for fevers caused by noninfectious sources depends on the specific diagnosis.

Keep these fever facts in mind next time you’re facing one.


How do you break a fever?

If you’re wondering how to break a fever, take over-the-counter fever-reducing medications such as ibuprofen or acetaminophen. Additionally, staying hydrated by drinking plenty of fluids and resting can help the body fight infection. Cool compresses or taking a lukewarm bath can also help lower body temperature.

Can allergies cause a fever?

Allergies don't usually cause a fever. This is because fevers are responses of your immune system to harmless substances. However, severe allergic reactions (anaphylaxis) can cause fever because of your body's heightened inflammatory response. 

When should you go to urgent care for a fever?

If you’re wondering when to go to urgent care for a fever, go if you’ve had a fever for more than 24 hours. Covid or Flu responds best to antiviral treatment if started within the first 48 hours. 

Can I treat a fever at home?

Treat a fever at home with hydration, rest, and over-the-counter fever-reducing medications like ibuprofen or acetaminophen.

What can urgent care do for a fever?

Urgent care can examine your fever symptoms and try to help determine the underlying cause. Healthcare providers can prescribe appropriate medications to manage symptoms. 

Written by Sarah Thebarge, Physician Assistant