A fever is your body deliberately raising its internal temperature to fight off an infection, and in most cases, the best thing you can do is keep yourself comfortable, stay hydrated, and let the process run its course. A temperature of 100.4°F (38°C) or higher, measured orally, is generally considered a fever. Most fevers in otherwise healthy adults and older children resolve on their own within a few days and don’t require aggressive treatment.
Why Your Body Runs a Fever
When your immune system detects bacteria or viruses, it releases signaling molecules that travel to a temperature-control center deep in your brain. These signals raise your body’s internal thermostat, essentially reprogramming it to a higher “set point.” Your body then works to reach that new target: blood vessels constrict, you shiver, and you feel cold even though your temperature is climbing. This controlled increase in heat activates immune cells, speeds up their movement through your body, and creates an environment that’s harder for many pathogens to thrive in.
This is why chasing a “normal” number on the thermometer isn’t always the right goal. The American Academy of Pediatrics emphasizes that the primary goal of treating a fever should be improving comfort, not forcing the temperature back to 98.6°F. There’s no evidence that reducing a fever, by itself, speeds recovery. Focus on how you or your child feels rather than fixating on the number.
How to Get an Accurate Reading
Where you place the thermometer matters. Armpit readings tend to run about half a degree Fahrenheit lower than oral readings, and nearly a full degree lower than rectal readings. For adults and older children, an oral reading is reliable and convenient. For infants under 3 months, a rectal thermometer gives the most accurate result and is the method pediatricians rely on for clinical decisions.
If you’re using an armpit thermometer and getting a reading that seems borderline, consider switching to an oral measurement before deciding your next step.
Staying Comfortable at Home
Most of what your body needs during a fever is simple: fluids, rest, and a comfortable environment.
Dehydration is the biggest practical risk of a fever. You lose more water through sweating and faster breathing than you normally would. Water is a fine starting point, but if you’re sweating heavily or dealing with vomiting or diarrhea, a drink with electrolytes helps replace sodium and potassium you’re losing. Avoid alcohol, caffeinated drinks, and sugary sodas, which can pull water from your body or irritate your stomach. Dark-colored urine, a dry mouth, dizziness, and headache are all signs you’re falling behind on fluids.
Dress in lightweight, breathable clothing. Bundling up in heavy blankets might feel tempting when you have chills, but trapping too much heat can push your temperature higher. A single light layer and a sheet is usually enough. Keep the room at a comfortable temperature rather than cranking up the heat.
When Fever-Reducing Medication Helps
You don’t need to take medication every time you have a fever. But if you’re miserable, achy, or unable to sleep, over-the-counter fever reducers can bring real relief.
Acetaminophen (Tylenol) can be taken every 4 to 6 hours, with no more than 5 doses in 24 hours. Ibuprofen (Advil, Motrin) can be taken every 6 to 8 hours, with no more than 4 doses in 24 hours. Both are effective at lowering temperature and easing body aches. Don’t take both at the same time without clear guidance from a pharmacist or doctor, and always follow the dosing instructions on the package for your weight.
For children, dosing is based on weight rather than age, so check the package carefully. Acetaminophen should not be given to infants under 8 weeks old, and ibuprofen should not be given to infants under 6 months old.
Fevers in Babies and Young Children
Fever in an infant under 3 months old is treated differently. Any rectal temperature of 100.4°F (38°C) or higher in a baby that young warrants a call to their pediatrician right away, even if the baby seems otherwise fine. Young infants don’t have fully developed immune systems, and a fever can be the only visible sign of a serious infection.
For older babies and toddlers, watch behavior more than the thermometer. A child with a 102°F fever who is drinking fluids, making eye contact, and playing between naps is generally in better shape than a child with a 100.5°F fever who is limp, unresponsive, or refusing to drink. A fever lasting longer than three days in a child also warrants a call to their doctor.
Signs of Dehydration in Children
- No tears when crying
- Dry lips and tongue
- Fewer than six wet diapers per day in infants, or no urination for eight hours in toddlers
- Sunken soft spot on an infant’s head
- Sunken eyes or dry, wrinkled skin
Offer small, frequent sips of fluid rather than trying to get a sick child to drink a large amount at once. Unsweetened fluids are best. Sugary juices and sodas can worsen diarrhea.
What to Do if a Seizure Happens
Febrile seizures, triggered by a rapid rise in temperature, affect some young children and are one of the most frightening things a parent can witness. They typically last a few seconds to a couple of minutes, though they can occasionally last up to 15 minutes. The child may shake, stiffen, lose consciousness, or have their eyes roll back.
If it happens, gently place your child on the floor on their side to prevent choking. Don’t put anything in their mouth and don’t try to restrain them. Note the time, because if the seizure lasts longer than 5 minutes, call 911 immediately. Most febrile seizures stop on their own and don’t cause lasting harm. Fever-reducing medication does not prevent febrile seizures from occurring.
When a Fever Needs Medical Attention
Most fevers don’t need a doctor’s visit. But certain symptoms alongside a fever signal something more serious. Seek immediate medical care if a fever comes with any of the following:
- Stiff neck, especially pain when bending the head forward
- Severe headache or unusual sensitivity to bright light
- Rash that appears suddenly
- Confusion, altered speech, or strange behavior
- Persistent vomiting
- Difficulty breathing or chest pain
- Pain when urinating
- Seizures or convulsions
These symptoms can point to infections like meningitis, kidney infections, or other conditions that need prompt treatment. A fever that lingers beyond three days in adults without an obvious cause (like a cold that’s clearly improving) is also worth getting checked out.