6 Common Causes of a 100+ Degree Fever

An adult body’s normal temperature varies somewhat from one person to another, and it changes within your own body at different times of day.

A “normal” temperature is usually considered to be 98.6 F (37 C), when taken using an oral thermometer. If it registers at 100 F (37.8 C) or higher, you’re generally said to have a fever.

Low-grade fevers, such as 100 F, are usually caused by a viral infection like the flu, and they can be treated at home with rest and plenty of fluids. Once the infection has run its course, your temperature will return to normal.

However, if your temperature registers at 103 F (39.4 C) or higher, you need to seek medical attention because too high of a temperature can lead to complications.

At Mercy Medical Urgent Care, Dr. Bilal Khoder and our staff treat fevers from all different causes at our Lake City, Florida, location. 

If you’re running a fever, especially if it’s accompanied by other symptoms, such as a rash, vomiting, or muscle stiffness, come to our office ASAP to get appropriate treatment.

What is a fever?

Your body’s temperature is a balance between two processes: heat production and heat loss. It’s regulated by the hypothalamus in the brain. Even when you're healthy, temperature fluctuates throughout the day. For example, it’s often lower in the morning and higher in the evening.

When your immune system encounters a pathogen, the hypothalamus sets your body’s
“ideal” temperature higher. This prompts the body to produce more heat and restrict heat loss. Shivering is one way you produce heat. Rapid muscle contractions produce heat as a byproduct. Also, when you use a blanket, you’re helping to trap your body’s heat near the skin.

Six common causes of a fever or elevated body temperature are:

1. A viral infection (e.g., influenza, COVID-19)
2. A bacterial infection (e.g., bronchitis, pneumonia, strep throat)
3. Heat exhaustion
4. Inflammatory conditions such as rheumatoid arthritis
5. Some drugs, such as those used to treat high blood pressure or seizures
6. Some immunizations, including those for diphtheria, tetanus, and acellular pertussis (DTaP), pneumococcal, and COVID-19

Fevers below 104 F (40 C) that are associated with common viral infections may help the immune system fight off the pathogen and aren’t generally considered harmful.

Symptoms that may accompany a fever

Depending on the cause of your fever, you may also experience:

• Sweating
• Chills and shivering
• Headache
• Muscle aches
• Loss of appetite
• Irritability
• Dehydration
• General weakness

You may feel bad, but none of these will hurt you.

More serious symptoms include:

• Severe headache
• Rash
• Unusual sensitivity to bright light
• Stiff neck and pain when you bend your head forward
• Mental confusion, strange behavior, or altered speech
• Persistent vomiting
• Difficulty breathing or chest pain
• Abdominal pain
• Pain when urinating
• Convulsions or seizures

These symptoms are serious and indicate an underlying cause that needs immediate attention.

If you’re running a fever and aren’t sure what to do, Mercy Medical Urgent Care can help. We’re open seven days a week. Walk in, or give us a call at 386-758-2944 to schedule.