A fever is a temporary rise in body temperature. It’s not considered an illness on its own, but rather a symptom that can be caused by many different conditions. Elevated body temperature can be a sign that the immune system is working — it’s most likely battling a type of infection or illness.
Fevers usually aren’t a cause for serious concern, and they usually go away when the infection does. But extremely high fevers that won’t go down may need treatment.
Here’s what you need to know about what temperature is considered a fever, common causes, at-home remedies, medications, and when to see the doctor.
Since the mid-1800s, normal body temperature has been considered 98.6 degrees, though newer studies suggest that the average person now is a little cooler than that — somewhere between 97.5 and 97.9.
There are several ways to measure body temperature, so it’s important to read the instructions that come with the thermometer. First, wash your hands with soap and warm water, and clean the thermometer with rubbing alcohol or soap and lukewarm water. Wait to take your temperature until at least 30 minutes after you eat or drink anything hot or cold.
Oral temperature: Turn on the digital thermometer and place the thermometer tip under your tongue. Close your mouth around the thermometer and keep it in place until the thermometer beeps.
Ear temperature: Turn on the digital thermometer and gently place it into the ear canal as indicated by the instructions. Hold the thermometer tightly in place until you hear the thermometer beep.
Temporal artery temperature: Turn on the digital thermometer and gently sweep it across your forehead or point it at the forehead.
Armpit temperature: A digital (oral) thermometer can be used in your armpit, if necessary, but it won’t be as accurate as taking it orally under your tongue. Turn on the digital thermometer and put it under your armpit, making sure it touches skin, not clothing. Hold the thermometer tightly in place until you hear the thermometer beep.
Rectal temperature: To take an infant or a child’s temperature rectally, use a thermometer specially made for that purpose, if possible. Follow the instructions to gently place the thermometer in the baby’s anus, and remove after it beeps.
Most experts agree that a fever is 100.4 degrees and over, and that’s the same for adults and children. But kids get more frequent and higher fevers than adults. That’s because their immune systems are still developing, and so more germs trigger a reaction. Adults may already be immune to those infections.
Although fevers usually go away within a few days, there are signs that a fever could be more serious.
Adults
Adults with a fever should call 911 or be taken to the nearest emergency room if they also have one or more of the following signs or symptoms:
Seizure
Loss of consciousness
Confusion
Trouble breathing
Severe headache
Stiff neck
Severe pain in your belly, back, or sides
Difficulty waking or extreme sleepiness
Any other unusual or concerning symptom
Infants and Children
Call 911 or go to the closest ER if a child’s fever is accompanied by any of the following:
Crying inconsolably
Difficult to wake up
Stiff neck
Red or purple spots on the skin
Breathing is difficult and doesn’t improve after the nose is cleared
Unable to swallow anything or drooling excessively
Extreme sluggishness or drowsiness
Pain or tenderness in the abdomen
Dehydration or decreased urination
Unusual behavior
Convulsions or seizures
In case of a seizure, put the child on their side. Do not put anything in their mouth.
Infants younger than 3 months with fever need immediate medical evaluation even if they don't display any other symptoms.
Fevers can often be managed at home with over-the-counter medications and comfort care. Effective at-home care tips for managing a fever include:
Stay hydrated. You can get dehydrated more quickly if you’re not drinking fluids while you have a fever. Drink what sounds good to you, but avoid overconsuming caffeine.
Rest and recover. Get plenty of rest and sleep to help your immune system fight off your illness.
Cool your fever. Adults and older children can use a cold pack to reduce a fever, though it’s best not to use them on small children and babies, because they may be too cold for their sensitive skin. A cool, wet washcloth or a cool or room-temperature bath or shower can help, too. If cooling-down methods cause chills, don’t continue; it may make you or your child feel worse.
Warm up if you have the shivers. It may seem counterintuitive, but it’s okay to use a blanket to help with your chills. But experts don’t recommend piling on blankets in an effort to “sweat it out.” That raises the risk of dehydration.
Over-the-counter medications such as nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen and acetaminophen can lower a fever and help with symptoms like headaches or muscle aches.
Aspirin can also help with fever, but it should not be given to children under 18, because it can cause Reye’s syndrome, a serious and potentially life-threatening condition.
In children, don’t give any medication, even over-the-counter fever reducers, without getting your healthcare provider’s okay first.
For adults and children, follow the dosing instructions on the label. Do not take more than recommended.
Rest and fluids are often enough until the fever breaks, but there are situations when you should contact your healthcare provider.
Adults
Adults with a fever should see a healthcare provider in the following situations:
The fever lasts several days or keeps coming back.
The fever doesn’t respond to fever-reducing medications.
You’re unable to eat or drink without vomiting.
You recently traveled to an area where a serious infectious disease such as malaria is common.
You had a recent hospital stay or a recent surgery or another medical procedure.
You get infections often.
You have a serious health condition, such as diabetes, heart disease, cancer, lupus, or sickle cell anemia.
You’re on chemotherapy and your temperature goes above 100.4 for longer than one hour, or above 101 degrees — even just one time.
Infants and Children
Nonurgent signs and symptoms in infants and children that should be checked by a healthcare provider include the following:
Infants up to 3 months with a temperature of 100.4 or higher. Fever in infants younger than 3 months could indicate a serious infection.
Children older than 3 months who have a fever of 100.4 or higher for more than three days or who are ill and acting sick by being fussy, clingy, or refusing to drink fluids
Temperature of 104 or greater or if the fever doesn’t come down with a fever-reducing medicine
Fever that lasts more than 5 days
Recurrent fever without any other symptoms for more than 7 days, even if the fevers last only a few hours
Fever and a chronic medical problem such as heart disease, cancer, lupus, or sickle cell anemia
Fevers are a part of life, but there are ways to reduce your chances of getting an infection or illness that have fever as a symptom.
Prevention tips include:
Adults and children should stay up-to-date on vaccinations as recommended for infectious diseases, such as influenza and COVID-19.
Wash your hands frequently, especially before eating, after using the toilet, after spending time in a crowd or around someone who's sick, after petting animals, and during or after travel on public transportation.
Show children how to wash their hands thoroughly, lathering both the front and back of each hand with soap, and rinsing completely under running water.
Use hand sanitizer when you don't have access to soap and water.
Try to avoid touching your nose, mouth, or eyes, especially during cold and flu season.
Cover your mouth when you cough and your nose when you sneeze. Whenever possible, turn away from others, and cough or sneeze into your elbow.
Avoid sharing cups, water bottles, and utensils.
A fever is typically a symptom of an underlying infection or illness and is usually not serious.
Home remedies, such as good hydration, rest, and over-the-counter medications like ibuprofen or acetaminophen, can help manage a fever.
In some cases, attention from a healthcare provider or even emergency medical care is necessary.
Preventive measures like staying up-to-date on vaccinations, washing hands frequently, and avoiding close contact with sick people can reduce the likelihood of fevers caused by infections.
