A fever is a rise in body temperature above the normal temperature of 98.6°F (although “normal” temperatures can vary slightly from person to person). Fevers usually result from an infection from either a virus or bacteria.

A number of medications can be effective in lowering a fever. However, in some instances, the best course of action might be to leave it untreated, as a fever is the body’s natural way of fighting off infection.

When is a fever cause for concern?

According to the CDC, a fever is defined as a person having a temperature of 100.4° F (38° C) or greater, feels warm to the touch, or gives a history of feeling feverish.

In adults, a fever isn’t considered serious until it reaches 103° F (39.4 C) or higher.

What about fevers in children?

For children, treatment guidelines depend on the age of your child:

  • If your infant is a newborn up to three months and has a temperature above 100.4 degrees, it’s time to see a doctor.
  • For children ages three months to three years, call your doctor if their fever is 102 degrees or higher.
  • For kids three years and older, a fever of 103 degrees or higher means it’s time to call your doctor.

Symptoms and causes of a fever


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

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


Fever or elevated body temperature could result from:

  • A bacterial infection.
  • A virus.
  • A malignant tumor.
  • Certain inflammatory conditions such as rheumatoid arthritis.
  • Heat exhaustion.
  • Some medications, such as antibiotics and drugs used to treat high blood pressure or seizures.
  • Some immunizations, such as the diphtheria, tetanus, and acellular pertussis (DTaP) or pneumococcal vaccine.

Treating a fever

OTC (over-the-counter) medications

The most common treatment for fever is over-the-counter medications such as acetaminophen (Tylenol, others) or ibuprofen (Advil, Motrin IB, others). It’s important to follow the label instructions for these medications as recommended by your doctor.

It’s especially important to avoid taking too much. High doses or long-term use of acetaminophen or ibuprofen may cause liver or kidney damage, and acute overdoses can be fatal.

If your child’s fever doesn’t reduce after the first dose, don’t give more medication. Call your doctor instead.

And always remember: don’t give aspirin to children. Doing so might trigger a rare, but potentially fatal, disorder known as Reye’s syndrome.

Prescription medications

If your doctor suspects your fever is caused by a bacterial infection like pneumonia or strep throat, he or she may prescribe an antibiotic.

Even though antibiotics aren’t an effective treatment against viral infections, your doctor can prescribe any number of antiviral drugs to treat a range of viral infections. However, the best way to treat most minor illnesses associated with viruses is to get plenty of rest and to drink plenty of fluids.

As noted, a number of different medications can be effective in lowering a fever.

In some instances, though, the best course of action might be to leave your fever untreated. A fever is the body’s natural way of fighting off infection.

Woman on couch engaging with provider on her mobile phone

More about kids and fever

“Normal” body temperatures can fluctuate

Body temperature fluctuates for everyone throughout the day, including children. Body temperature can also be influenced by activity level and other factors. That means it’s perfectly normal for your child’s temperature to vary from day to day. Remember, you should only start to worry about a fever is it’s 100.4˚ F or higher.

Here are some helpful reminders for when you shouldn’t worry about your child’s fever:

  • If it lasts less than five days and if your child’s behavior is relatively normal. There’s nothing to worry about as long as your child continues to be playful and is eating and drinking normally. You may note that your child does seem to be more tired than usual.
  • A low-grade fever (less than 100˚ F) after recent immunizations. Low-grade fevers are fairly common and are considered normal if they don’t persist longer than 48 hours.
Two schoolkids wearing masks

Frequently asked questions (FAQs) about fever

Most fevers tend to last between one to three days, although a persistent or recurrent fever may last or keep coming back for up to 14 days. If your fever lasts longer than normal, you may have a more serious infection that will require immediate medical attention.

A low-grade fever is classified as any fever between 99.6° F to 100.3° F.

Yes. Extreme dehydration can lead to a dangerous spike in body temperature that may require medical attention if the fever exceeds 101 degrees F.

Yes. When you get a sinus infection either due to a virus or bacteria, your body raises its internal temperature in an effort to try and kill the infection off. A low-grade fever is a common symptom of a sinus infection.

Yes. A urinary tract infection (UTI) is a common infection that happens when bacteria, often from the skin or rectum, enter the urethra, and infect the urinary tract. This infection can impact either the bladder or the kidneys, with a kidney infection being more serious.

Yes. It is possible to have COVID-19 with minimal or even no symptoms at all.

Yes. According to the CDC, common symptoms of food poisoning are:

  • Diarrhea.
  • Fever.
  • Nausea.
  • Stomach cramps.
  • Upset stomach.
  • Vomiting.

Yes. Even though they’re symptoms that often appear together, it’s possible to have chills without a fever and fever without chills.

MedlinePlus: National Library of Medicine. Fever (https://medlineplus.gov/ency/article/003090.htm)

National Center for Biotechnology Information (NCBI): National Library of Medicine. Fever as an important resource for infectious diseases research (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4869589/)