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7 Causes of Persistant Low Grade Fever

7 Causes of Persistant Low Grade Fever

What does a low-grade fever mean? If you have a cold, or more commonly the flu, you may have a fever as well, but not all are the same. Fevers are defined as any body temperature above 98.6° F (37° C). Some people may talk about a low-grade fever versus a regular fever or a high-grade fever. These terms are not universally defined, but it is important to monitor the degree of your fever in the context of your cold or flu and take appropriate action to treat.


Depending on what's causing your fever, additional fever signs and symptoms may include:

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

A Regular Fever vs. a Low-Grade Fever (LGF)

You can monitor your fever by simply taking your temperature. A low-grade fever is often classified as an oral temperature that is above 98.6° F (37° C) but lower than 100.4° F (38° C) for a period of 24 hours. Fevers, though uncomfortable, play a key role in helping your body fight off many infections.

What causes low-grade fever?

Fevers often accompany infections. Body temperature can be elevated by physical activity and environmental factors, such as wearing heavy clothing or a high ambient temperature. A low-grade fever may also occur following immunizations, during teething, or as a symptom of cancer or inflammatory and autoimmune conditions. It can also occur as side effect of some medications.

Infectious causes of low-grade fever:

  • Bacterial infection, such as Strep throat or scarlet fever
  • Cellulitis (skin infection)
  • Childhood diseases, such as chickenpox, fifth disease, measles, mumps, whooping cough
  • Cold, flu, or other viral infections
  • Ear infection
  • HIV or AIDS
  • Lung infections, such as bronchitis, pneumonia, and tuberculosis
  • Mononucleosis
  • Sinus infection
  • Urinary tract infections


Generally, if the fever does not cause discomfort, the fever itself doesn’t necessarily have to be treated. It is not necessary to treat a fever unless instructed to do so by a doctor.

The following fever-reducing medications may be used at home:

  • Acetaminophen (Tylenol and others) can be used to lower a fever. The recommended dose can be suggested by the child's pediatrician. Adults without liver disease or other health problems can take 1,000 mg every six hours or as directed by a physician. The makers of Tylenol state the maximum recommended dose of acetaminophen per day is 3,000 mg, or six extra-strength tablets per 24 hours, unless directed otherwise by a doctor. Regular-strength Tylenol tablets are 325 mg; the recommended dosage for these is two tablets every four to six hours, not to exceed 10 tablets per 24 hours.
  • Ibuprofen (Motrin, Advil) can also be used to break a fever in patients over 6 months of age. Discuss the best dose with a doctor. For adults, generally 400 mg to 600 mg (two to three 200 mg tablets) can be used every six hours as fever reducers.
  • Naproxen (Aleve) is another nonsteroidal anti-inflammatory drug (NSAID) that can temporarily reduce fever. The adult dose is two tablets every 12 hours.
  • Aspirin should not be used for fever in children or adolescents. Aspirin use in children and adolescents during a viral illness has been associated with Reye's syndrome. Reye's syndrome is a dangerous illness that causes prolonged vomiting, confusion, and even coma and liver failure.

Most fevers will go away in a few days with the appropriate and prompt treatment. It is important to follow up with a doctor to be sure the cause of the fever is treated correctly. This may be done in a few days to weeks after the initial visit, depending on the cause. If symptoms worsen, or if the fever lasts longer than a week without treatment, see a doctor immediately.