Acetaminophen (Tylenol) and ibuprofen (Advil, Motrin) are the two most common and effective medicines for reducing fever in both adults and children. Both work by lowering levels of a chemical called prostaglandin E2 in the brain, which is what resets your body’s internal thermostat higher when you’re fighting an infection. A third option, naproxen sodium (Aleve), also reduces fever and lasts longer between doses.
Acetaminophen for Fever
Acetaminophen is the most widely used fever reducer. It works well, acts quickly (usually within 30 to 60 minutes), and is gentle on the stomach. For adults, the standard dose is 500 to 1,000 mg every four to six hours as needed. The critical safety limit is 4,000 mg in 24 hours, though extra-strength formulations cap the recommendation at 3,000 mg per day. Going over these limits raises the risk of serious liver damage, especially if you drink alcohol regularly.
One thing to watch: acetaminophen is an ingredient in dozens of combination products, from cold medicines to sleep aids. If you’re taking any other over-the-counter medication while treating a fever, check the label to make sure you aren’t doubling up.
Ibuprofen for Fever
Ibuprofen belongs to a class of drugs called NSAIDs, which reduce fever and also fight inflammation. This makes it a particularly good choice when your fever comes alongside body aches, sore throat, or swollen glands. The typical adult dose for pain is 400 mg every four to six hours as needed.
Unlike acetaminophen, ibuprofen can irritate the stomach lining, so take it with food or a glass of water. People with kidney problems, stomach ulcers, or a history of gastrointestinal bleeding should be cautious with ibuprofen and other NSAIDs.
Naproxen Sodium as a Longer-Lasting Option
Naproxen sodium lasts longer than both acetaminophen and ibuprofen, so you take it less often. Adults and children 12 and older can take one tablet every 8 to 12 hours, with the option to take two tablets for the first dose. The daily maximum is three tablets in 24 hours. It carries the same stomach-related risks as ibuprofen since it’s also an NSAID. If your fever is mild and you prefer fewer doses throughout the day, naproxen is a reasonable choice.
Fever Medicine for Children
For children, acetaminophen and ibuprofen are the go-to options, but dosing is based on your child’s weight rather than age. If you don’t know the weight, age can serve as a rough guide, but weight is more accurate. Children’s liquid acetaminophen is standardized at 160 mg per 5 mL, which makes measuring simpler than it used to be.
Acetaminophen can be given every four hours, up to five doses in 24 hours, for children under 12. Children over 12 can use extra-strength tablets every six hours, up to six doses per day. Children under 2 should not receive acetaminophen without a doctor’s guidance. Ibuprofen can be used in children 6 months and older.
One important rule: never give aspirin to children or teenagers. Aspirin has been linked to Reye’s syndrome, a rare but serious condition that causes swelling in the liver and brain. The risk is highest when a child has a viral illness like the flu or chickenpox, which is exactly when you’d be reaching for a fever reducer.
Should You Alternate Acetaminophen and Ibuprofen?
Some parents and even some doctors suggest alternating between acetaminophen and ibuprofen every few hours to keep a fever down more consistently. This is common advice, but it’s not well supported. The American Academy of Family Physicians has cautioned against alternating regimens because there’s no evidence the combination works better than either medicine alone, and the complicated timing (every four hours for one, every six for the other) creates real potential for accidental overdose. Sticking with one medicine at a time is simpler and safer.
What Temperature Counts as a Fever
The number that counts as a fever depends on where you measure. A rectal, ear, or forehead temperature of 100.4°F (38°C) or higher is a fever. For an oral reading, the threshold is 100°F (37.8°C). Armpit temperatures run lower, so anything at or above 99°F (37.2°C) is considered elevated. These distinctions matter most for infants and young children, where small differences in temperature can change the level of concern.
When a Fever Needs More Than Medicine
Most fevers don’t need aggressive treatment. A low-grade fever is your immune system working, and bringing it down is really about comfort. That said, certain situations call for prompt medical attention.
For infants under 3 months, any rectal temperature of 100.4°F or higher warrants a call to your doctor right away. Babies between 3 and 6 months need evaluation if their temperature rises above 102°F, or if they seem unusually irritable or sluggish even with a lower fever. For children between 7 and 24 months, a fever above 102°F that lasts more than a day without other symptoms should be checked out. Any child who has a seizure with a fever needs emergency care, and you should call 911 if the seizure lasts more than five minutes.
For adults, a temperature of 103°F (39.4°C) or higher is worth a call to your doctor. Seek immediate medical attention if a fever is accompanied by a stiff neck, rash, sensitivity to bright light, confusion, persistent vomiting, difficulty breathing, chest pain, or seizures. A fever lasting more than three days in a child, even if it seems mild, also deserves medical evaluation.