Is Your Fever Caused by High Body Temperature or a Sign of Infection? 

August 27, 2025 | Tags: Wellness

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A rising body temperature is like flashing hazard lights: It's a way of signaling that something is going on and needs to be addressed. While fevers aren’t usually a cause for concern and can be managed at home, you’ll want to keep an eye on any developing or worsening symptoms, especially with infants, toddlers and children. 

What is a fever? 

A fever is your body temperature rising past normal levels. Baseline or “normal” body temperature has been defined as 98.6 degrees Fahrenheit (37 degrees Celsius) but can vary from person to person and fluctuate for a variety of reasons: 

• Time of day 
• During exercise 
• Throughout menstruation cycle 

The set standard for a fever is 100.4 F (37 C) when measured orally and is typically a sign that your immune system has been activated to fight an infection. The fever itself isn’t an illness, but more of a symptom that can be caused by conditions like: 

• Urinary tract infections (UTIs).
• Gastrointestinal (GI) infections.
• Bacterial infections.
• Viral infections, like the flu or COVID-19.

A fever or elevated temperature can also result from:

• Heat-related illnesses, like heat exhaustion.
• A reaction to certain medications or immunizations. 
• Some autoimmune conditions.
• Cancer.

A low-grade fever indicates a slightly higher than normal body temperature and can still activate your immune system. While there's no standard range, a low-grade fever typically falls between 99.5 F (37.5 C) and 100.3 F (37.9 C). 

Be aware of fever symptoms  

A fever isn’t just an elevated body temperature; there are other symptoms you can experience, including: 

• Headache 
• Irritability  
• Muscle or body aches 
• Sweating or flushed skin 
• Loss of appetite or dehydration 
• Chills, feeling cold or shivering 
• Fatigue or feelings of general weakness 

Fevers can be serious for infants and young children as they can’t regulate their body temperature well or verbalize how they feel. Symptoms may also be harder to spot but can include:  

• Excessive thirst 
• Decreased urination 
• Crying or fussiness 
• Paleness and flushness 
• Earache or pulling on ears 

How to best monitor fevers 

The best way to diagnose and monitor a fever is with a thermometer. Different types of thermometers are used to take temperatures from different areas of the body: 

• Oral 
• Rectal 
• Ear (tympanic) 
• Forehead (temporal artery) 

Results can vary depending on where a temperature is taken. For example, rectal and ear thermometers typically measure higher than oral thermometers by 1.0 F (0.6 C) and forehead thermometers typically measure 1.0 F (0.6 C) lower than oral thermometers. Children should stay home from school or childcare until they’ve been fever free for 24 hours. 

Treating a fever 

Fevers can be treated depending on their temperature range with regular monitoring: 

• Mild fevers (under 101 F or 38.8 C): These can be treated without medication and at-home care. 
• High fevers (above 102 F or 38.9 C): Discomfort from these can be treated with over-the-counter medications, like acetaminophen or ibuprofen. Follow the label directions for how much to take or give to your child and how often. Do not give children under the age of 17 aspirin, as it may cause Reye’s syndrome, which can be fatal. 

To aid in recovery, consider the following tips: 

• Take it easy and get plenty of rest. 
• Stay hydrated by drinking plenty of fluids (oral rehydration solutions with electrolytes are a good choice) and consuming hydrating foods, like soup, popsicles or flavored gelatin. 
• Wear lightweight clothes, use lightweight blankets and keep rooms at a comfortable temperature – not too hot or cold. 

When a fever is something more serious  

While most fevers tend to resolve in a few days, higher body temperatures can sometimes be a sign of a more serious infection or health concern. For infants and toddlers, contact their primary care provider (PCP) if they experience the following: 

Children with a fever should still be responsive. Contact their PCP if they: 

• Become listless, confused or exhibit poor eye contact with you. 
• Have a fever higher than 104 F (40 C). 
• Have a fever that lasts longer than three days. 
• Have a seizure associated with the fever. 

Contact your PCP if your fever goes away and comes back in a few days. Go to the nearest emergency room or call 911 if you have a fever of 103 F (39.4 C) along with the following: 

• Pain or tenderness in your abdomen. 
• Stiff neck or severe headache. 
• Persistent vomiting. 
• Seizures. 
• Difficulty breathing or chest pain. 
• Difficulty walking or extreme sleepiness. 

If you don’t have a PCP, Medical Mutual can help. Use our Find a Provider tool in My Health Plan to find one in your plan’s network or call the Customer Care number listed on your member ID card.