What Is a Low-Grade Fever?

A person has a fever if their temperature is higher than their normal body temperature as a disease or illness response. There are different levels of fever, including low-grade fevers ranging from 99.1 degrees to 100.4 degrees Fahrenheit.

Causes of low-grade fevers can be bacterial or parasitic infections; even some vaccines can cause a low-grade fever. Here's what you need to know if your temperature is reading a little higher than usual and when a healthcare consult is necessary.

Low-Grade Fever Symptoms

There's no true medical definition of a low-grade fever, but a general estimate is a temperature between 99.1 degrees Fahrenheit and 100.4 degrees Fahrenheit. It's essential to note that fevers are a symptom of illness. They may also present with a person experiencing chills or shivering.

Symptoms are slightly different for children and can include:

• Flushed skin
• Increased thirst or sweat
• Skin that's warm to the touch

The estimated low-grade fever range is based on the variety of normal body temperatures. For most people, a "normal" body temperature falls somewhere around 98.6 degrees Fahrenheit. However, not everyone's body temperature is exactly 98.6 degrees Fahrenheit. A normal range is from 97 degrees Fahrenheit to 99 degrees Fahrenheit.

Because normal body temperature varies so much from person to person, so do fever temperatures. If a person's normal body temperature is typically lower, the jump of their fever temperature may also be lower, possibly only registering as a low-grade fever.

What Causes a Low-Grade Fever?

Various types of bacterial, parasitic, and viral infections can all be responsible for fevers, including low-grade fevers. Other potential causes include:

• Autoimmune and inflammatory disorders
• Certain medications like antihistamines or seizure medications
• Some cancers (e.g., leukemia or non-Hodgkin lymphoma)
• Teething
• Vaccinations

Some people may also think a low-grade fever results from a less severe infection, but that's not the case. The severity of a fever doesn't depend on the severity of an infection.

The older you get, the less likely you may be to develop a true fever. That's because sometimes normal body temperature—and, ultimately, fevered body temperature—may drop with age.

Treatment

Mild fevers without other symptoms or problems may be resolved with rest and drinking plenty of fluids. You can also do the following to help break a fever:

• Bathing in lukewarm water
• Taking acetaminophen or ibuprofen if age-appropriate—children aged 6 months or younger should not be given ibuprofen unless directed by a doctor; short-term use of ibuprofen is considered safe in infants older than 3 months with body weight above 5-6 kilograms (kg) when special attention is given to their hydration
• Wearing lightweight clothing or using lightweight blankets
  

When To Contact a Healthcare Provider

Don't rush to a healthcare provider if you have a fever, low-grade or not, and no other symptoms. Call a healthcare provider's office to determine what you should do. You and the provider might be able to work out a treatment plan via a telehealth appointment, saving you an office visit if fever is the only symptom you have.

The only exception to receiving medical care for fever as an only symptom is if it occurs in young children. Infants younger than three months old with a fever higher than 100.4 degrees Fahrenheit or children aged three to 12 months old with a fever of 102.2 degrees Fahrenheit or higher need immediate medical attention.

Immediate medical care is also necessary for symptoms such as:

• A long-lasting fever—more than 48 to 72 hours
• A persistent fever of 103 degrees Fahrenheit or higher
• Bad headache
• Blue or pale lips, tongue, or nails
• Confusion
• Difficulty breathing or walking
• Fevers of 105 degrees or higher that make you feel uncomfortable or don't improve with treatment
• Fevers that disappear but return over a week's time
• Fevers accompanying new rashes, bruises, or painful urination
• Refusal of arm and leg movement or crying but can't be consoled—for children
  
• Seizures
• Stiff neck
  

A Quick Review

A low-grade fever refers to a body temperature that is just slightly above normal but is not high enough to be considered a full-on fever. Some people, like older adults, may be more likely than others to experience low-grade fevers.

If the high temperature won't drop, is above 103 degrees Fahrenheit, or is accompanied by other symptoms, you'll want to talk to a healthcare provider right away. Healthcare providers can determine what the best course of treatment will be for your situation.