A fever–as anyone who has ever come down with the flu knows–is an elevated body temperature. Technically, 98.6 degrees Fahrenheit is considered normal; a fever is defined as a temp of 100.4 Fahrenheit or higher.
When you’re fighting an infection, the part of your brain responsible for regulating temperature, called the hypothalamus, kicks up your internal thermostat. It’s part of your body’s way of defending itself against those foreign invaders.
Gustavo Ferrer, MD, president of Intensive Care Experts in Weston, Florida, says some can be treated at home, while others require medical attention. The appropriate response depends on a person’s age, symptoms, overall health, and how high the fever spikes, he explains.
Read on to learn more about fever in adults and children, what you can do to break a fever, and when to see a doctor.
Right off the bat, if you think you have a fever, take your temperature. Body temps vary from person to person, by time of day, and due to other factors–even during ovulation in women who menstruate. If your thermometer reads a degree lower or higher than normal, don't sweat it.
You enter fever territory when your temperature reaches 100.4 or above. (A rectal temperature is thought to be the most accurate gauge in young kids.)
While fevers are usually caused by viruses, like the ones that cause colds or the flu, fevers can also signal bacterial infections (such as strep throat or a UTI), certain inflammatory and immune disorders (such as rheumatoid arthritis), or cancer.
3 of 11Getty Images
Pay no mind to the old saying, "feed a cold, starve a fever." In truth, colds can produce fever too, and when you’re fighting a fever, liquids are your friend.
“Fever will dehydrate you, and you have to replace what you have lost,” explains Dr. Ferrer, who also serves as director of the pulmonary fellowship program at Aventura Hospital and Medical Center.
Water, tea, and chicken broth are all smart options. Your pediatrician may recommend an electrolyte solution for a young child.
4 of 11Getty Images
No appetite? Don’t eat!
When your body is feverish due to an infection of some sort, you may also have an upset stomach or nausea, not to mention a lack of appetite. It can be hard to keep food down or simply unappealing to eat, Dr. Ferrer explains, so “never force anybody to eat.”
But if you do feel like eating, a steamy bowl of chicken soup may be just what the doctor ordered. In a famous study published nearly two decades ago, researchers showed that chicken soup actually does have . It slows the movement of infection-fighting white blood cells, and that action is thought to help alleviate upper respiratory symptoms.
5 of 11Thinkstock/Getty Images
Stay comfortably cool
There’s no evidence that layering on blankets “and trying to sweat out the fever” has any benefit, Dr. Ferrer says.
Instead, you’ll probably feel better if you stay cool, he says. One way to beat the heat is to take a lukewarm or cool shower or bath at a temperature that’s comfortable to you. Applying cool compresses to the neck, armpits, or forehead can also help cool the skin through evaporation. These methods won’t treat the underlying cause of the fever–but they can help ease some discomfort as your body fights off a bug.
6 of 11Winnie Au/Getty Images
Get some rest
Give in to the urge to crawl into bed! When you have a fever, it means your immune system is working overtime to battle whatever infection or disease is making you ill.
Give your body a fighting a chance by catching a few winks. Studies suggest that sleep boosts immune system function.
Acetaminophen (Tylenol) and ibuprofen (Advil, Motrin) are the go-to medicines for reducing fever in adults and children. Aspirin is also effective in adults but should never be given to children or teenagers. It has been linked to a rare condition called that causes brain swelling and liver damage in young people battling a viral infection, according to the Mayo Clinic.
Parents: Make sure to administer the correct dosage of acetaminophen or ibuprofen based on your child’s age and weight. And know that acetaminophen may be hidden in many over-the-counter medications taken to relieve cold and flu symptoms. You don’t want to take too much, Dr. Ferrer warns, because it “continues to be one of the most common reasons for liver failure.”
8 of 11Lau Yan Wai/Getty Images
Take your infant to the doctor
Call your pediatrician any time your baby has a fever of 100.4 or higher.
Children under 1, especially infants 6 months or younger, are extremely vulnerable when they have a fever because they can become dehydrated quickly, Dr. Ferrer explains.
9 of 11Getty Images
Take your sick child to the doctor
Fever in children 6 months to 5 years of age can trigger febrile seizure, a type of seizure that occurs within the first few hours of a fever. The American Academy of Pediatrics (AAP) advises parents to call the doctor when a child has a .
You should also call a doctor if your child is feverish and looks very ill, is unusually drowsy, is very fussy, or has other symptoms, such as a stiff neck, a severe headache, a sore throat, ear pain, an unexplained rash, or repeated vomiting or diarrhea.
A worsening fever or one that hangs on for more than two days in a tot younger than 2 or three days in an older child also requires medical attention, as does a high fever. Some clinicians define “high fever” in children as a temperature of 102 degrees or above. “High fever, going beyond 103, is a red flag,” Dr. Ferrer says.
10 of 11Getty Images
Take yourself to the doctor
In adults, a fever of less than 101 is considered mild. At 103 degrees or higher, it’s a different story. “If you have a temperature that is going beyond 103 or 104 and it’s persistent, this is the time that you’ve got to consider seeing the doctor,” Dr. Ferrer says.
He tells patients to note the constellation of symptoms that accompany their fever. Burning with urination in addition to a fever, for example, may be a sign of a urinary tract infection.
To get our top stories delivered to your inbox, sign up for the
11 of 11MJFelt/Getty Images
Seek emergency care
Head directly to the emergency room when a fever is accompanied by shortness of breath or coughing up blood, Dr. Ferrer says. Shortness of breath is an early sign of respiratory failure and should be taken very seriously, he adds.
If your child experiences a fever-induced seizure that doesn’t stop after five minutes, dial 911 or your local emergency number, the AAP advises.