What Is Considered a Low-Grade Fever?

A person has a fever if their body temperature is higher than normal, usually in response to an infection or illness. There are different levels of fever, including low-grade fevers that range from 99.1 to 100.4 degrees.

Causes of low-grade fevers can be viral, bacterial, or parasitic infections. You may also have a sore throat, headache, and body aches. Some vaccines can cause a low-grade fever. Autoimmune and inflammatory disorders, as well as some cancers, may cause a persistent low-grade fever.

Symptoms of a Low-Grade Fever

There's no true medical definition of a low-grade fever. A general estimate is a body temperature between 99.1 and 100.4 degrees.

Fevers are a symptom of illness and may present with 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. A "normal" body temperature usually falls somewhere around 98.6 degrees. Not everyone's body temperature is exactly 98.6 degrees. A normal range is from 97 to 99 degrees.

Normal body temperature varies so much from person to person, and so do fever temperatures. The jump to a fever may be lower if a person's normal body temperature is typically lower, possibly only registering as a low-grade fever.

Causes

Bacterial, parasitic, and viral infections can be responsible for fevers, including low-grade fevers. Other possible 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 does not depend on the severity of an infection.

The older you get, the less likely you may be to develop a true fever. Normal body temperature—and, ultimately, fevered body temperature—may drop with age.

How To Treat a Low-Grade Fever

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

• Bath in lukewarm water
• Take Tylenol (acetaminophen) or Advil (ibuprofen)—children aged 6 months and younger should not be given ibuprofen unless directed by a healthcare provider
• Wear lightweight clothing or using lightweight blankets
  

When To Contact a Healthcare Provider

Do not rush to a healthcare provider if you have a fever, low-grade or not, and no other symptoms. Call their office to determine what to do. You and a healthcare 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.

Adults

Certain symptoms in adults warrant a visit to a healthcare provider. Get medical attention for a fever if you have:

• A fever of 105 degrees or higher that does not come down with treatment or lasts longer than 48 to 72 hours
• An underlying condition like cystic fibrosis, heart problems, diabetes, or lung disease
• Fevers, even low-grade ones, that come or go for a week or more
• New rashes or bruises
• Painful urination
• Recently traveled to a different country
• Weak immune system
  

Infants and Children

Consult a healthcare provider if your infant or child has any of the above symptoms, as well as a cough, earache, or sore throat. Talk to a healthcare provider if your infant or child has a fever and has been recently vaccinated.

Get medical attention if your infant is younger than 3 months with a fever higher than 100.4 degrees. Children aged 3 to 12 months with a fever of 102.2 degrees or higher also need immediate medical attention.

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 have low-grade fevers.

Talk to a healthcare provider right away if you have a high temperature that will not drop, is above 103 degrees, or is accompanied by other symptoms. They can determine what the best course of treatment will be for your condition.