Most fevers don’t need aggressive treatment. A temperature of 100.4°F (38°C) or higher counts as a fever, and the most effective relief comes from over-the-counter pain relievers, staying hydrated, and resting. That said, how you approach a fever depends on how high it is, how you’re feeling, and your age, so the details matter.
Why Your Body Creates a Fever
When your immune system detects an infection, it releases signaling molecules that reach the temperature-control center in your brain. These signals trigger the production of a compound called prostaglandin E2, which essentially raises your body’s internal thermostat. Your brain now treats your normal temperature as “too cold,” so you shiver, feel chilled, and your body generates heat until it reaches the new, higher set point.
This process is actually useful. Research from the National Institutes of Health found that at fever temperature (around 102.2°F), immune cells called T cells multiply faster, produce more signaling molecules, and ramp up their metabolism compared to normal body temperature. In other words, a moderate fever helps your immune system work harder. That’s why many doctors recommend treating the discomfort of a fever rather than trying to eliminate the fever itself.
Over-the-Counter Fever Reducers
Acetaminophen (Tylenol) and ibuprofen (Advil, Motrin) are the two main options. Both work well, but they operate differently. Acetaminophen acts primarily in the brain to lower the temperature set point. Ibuprofen does that too, but also reduces inflammation throughout the body, which can help if your fever comes with body aches or a sore throat.
For adults, a standard dose of ibuprofen is 400 mg every six to eight hours. Follow the package directions for acetaminophen and don’t exceed the daily maximum listed on the label, as too much can damage the liver. Ibuprofen should be taken with food to protect your stomach.
For children, dosing is based on weight, not age. Ibuprofen should not be given to babies younger than 6 months. Always use the measuring device that comes with the medication rather than a kitchen spoon.
Alternating Acetaminophen and Ibuprofen
If one medication alone isn’t bringing enough relief, alternating the two is a common approach. A 2024 meta-analysis published by the American Academy of Pediatrics found that both combined and alternating therapy were significantly more effective at reducing fever by the four-hour mark compared to acetaminophen alone. The study also found no difference in side effects between single-drug and dual-drug approaches when used at appropriate doses in the short term.
The risk with alternating is simple: it’s easy to lose track of which drug you gave and when, which can lead to accidental overdosing. If you go this route, write down each dose with the time. A typical pattern is giving one medication, then the other three hours later, and continuing to alternate so each individual drug stays within its own dosing schedule.
Staying Hydrated
Fever increases the amount of fluid your body loses through skin and breathing. For every degree above 98.6°F, you lose an additional 2.5 mL per kilogram of body weight per day. For a 150-pound adult running a 102°F fever, that’s roughly an extra 8 ounces of fluid lost daily on top of your normal needs. Higher fevers and sweating push that number up further.
Water is fine. So are diluted juice, broth, and oral rehydration solutions. Cold drinks can feel soothing. For children, offer small sips frequently rather than trying to get them to drink a large amount at once. Signs of dehydration to watch for include dark urine, dry lips, dizziness when standing, and in young children, fewer wet diapers than usual.
Physical Cooling That Actually Helps
A lukewarm bath can bring some relief, especially for children. The key word is lukewarm. Cold water or ice baths cause shivering, which is counterproductive because shivering is your body’s way of generating heat. It will actually drive your temperature up and make you more uncomfortable.
Other simple measures that help: dress in lightweight clothing, keep the room comfortably cool, and use a light sheet instead of heavy blankets. A cool washcloth on the forehead won’t lower your core temperature, but it can feel good. Rest is important because physical activity generates heat and diverts energy your immune system could use.
Taking Your Temperature Accurately
Rectal thermometers give the most accurate reading, but oral thermometers provide similar accuracy and are far more practical for most people. Forehead and ear thermometers are convenient but can be less precise. Temperatures vary slightly depending on where you measure them, and there’s no reliable formula for converting between sites. The best approach is to use the same method each time so you can track whether your fever is rising or falling.
For infants under 3 months, a rectal thermometer is the standard. For older children and adults, an oral reading taken under the tongue with the mouth closed for the recommended time works well. Avoid taking an oral reading right after drinking something hot or cold, as it will skew the result.
When a Fever Needs Medical Attention
Age is the single biggest factor in how seriously to take a fever. For babies under 3 months, any rectal temperature of 100.4°F or higher warrants a call to the pediatrician right away, even if the baby seems fine. The AAP has specific evaluation guidelines for febrile infants as young as 8 days old, and the youngest babies (under 22 days) typically receive a comprehensive workup because their immune systems are so immature that serious infections can look deceptively mild.
For babies 3 to 6 months old, a temperature above 102°F or unusual irritability and sluggishness are reasons to call. For children 7 months to 2 years, a fever above 102°F that lasts more than a day needs attention. Any child with a fever lasting more than three days should be evaluated regardless of the number on the thermometer.
For adults, the threshold is 103°F or higher. Seek immediate care if a fever at any level comes with:
- Stiff neck, especially pain when bending your head forward
- Severe headache with sensitivity to bright light
- Rash
- Confusion, altered speech, or unusual behavior
- Persistent vomiting
- Difficulty breathing or chest pain
- Seizures (call 911 if a seizure lasts more than five minutes)
When You Don’t Need to Treat It
A low-grade fever in an otherwise healthy adult or older child who feels reasonably okay doesn’t necessarily need medication. Since fever enhances your immune response, letting a mild fever run its course may help your body fight the infection faster. The goal of treatment is comfort, not hitting a specific number on the thermometer. If you or your child can rest, drink fluids, and sleep, that may be all you need. Reach for medication when the discomfort is interfering with rest or fluid intake, or when the temperature climbs high enough to be concerning.