The two fever reducers safe for babies are acetaminophen (Tylenol) and ibuprofen (Advil, Motrin), but which one you can use depends entirely on your baby’s age. Acetaminophen can be given to babies 12 weeks and older (with a doctor’s guidance for children under 2), while ibuprofen is off-limits until 6 months of age. Before reaching for any medication, though, your baby’s age and the height of the fever determine whether you need medicine at all, or whether you need an emergency room.
Know the Fever Threshold
A baby has a fever when their rectal temperature hits 100.4°F (38°C) or higher. Rectal readings are the most accurate for infants. An armpit temperature of 99°F or higher also suggests a fever, though it’s less precise. If you’re unsure whether your baby’s temperature is elevated, a rectal thermometer gives you the clearest answer.
When Fever Needs Immediate Medical Attention
Age matters more than the number on the thermometer for very young babies. If your baby is younger than 2 months and has a rectal temperature of 100.4°F or higher, go to an emergency department immediately. Do not give any fever-reducing medication first. At this age, even a low-grade fever can signal a serious infection that needs testing right away.
For babies between 2 and 3 months old, call your pediatrician immediately if their temperature reaches 100.4°F. Your doctor will tell you whether to come in or head to the ER. For babies of any age, call your doctor if they haven’t had a wet diaper in 6 to 8 hours, since that’s a sign of dehydration.
Acetaminophen: The First Option
Acetaminophen is the only fever reducer recommended for babies between 12 weeks and 6 months old. It typically starts working within 30 to 60 minutes and lasts about 4 hours. For children under 2, check with your pediatrician before giving it so you get the right dose for your baby’s weight.
Both infant and children’s liquid acetaminophen now come in the same concentration: 160 mg per 5 mL. This standardization happened in 2011 to prevent dosing errors, since the old infant drops were much more concentrated. If you happen to find an old bottle in the back of a cabinet, throw it out. Always use the syringe or measuring device that comes in the box, not a kitchen spoon, and dose based on your baby’s current weight rather than age.
Ibuprofen: For Babies 6 Months and Older
Once your baby turns 6 months old, ibuprofen becomes an option alongside acetaminophen. It kicks in within 30 to 60 minutes, similar to acetaminophen, but generally lasts longer (6 to 8 hours compared to about 4). Check with your doctor before using it for babies under 2 years old or those weighing less than 12 pounds.
Ibuprofen dosing is based on weight. For a baby weighing 12 to 17 pounds, the typical dose of children’s liquid ibuprofen (100 mg/5 mL) is 2.5 mL. For babies 18 to 23 pounds, the dose increases to 4 mL. Always read the label carefully, because infant drops and children’s liquid have different concentrations, and using the wrong measuring device can lead to giving too much or too little.
Should You Alternate Between the Two?
You may have heard advice about switching back and forth between acetaminophen and ibuprofen every few hours. The American Academy of Pediatrics actually recommends against routinely alternating or combining these two medications. The concern is that juggling two different drugs with different dosing schedules increases the chance of accidentally giving a double dose or losing track of timing.
The safer approach is to pick one medication and make sure you’re giving the correct dose at the right intervals. If a single medication isn’t bringing your baby’s fever down enough to keep them comfortable, talk to your pediatrician before adding the second one. A short course of alternating can be reasonable when one drug alone isn’t enough, but it should be a deliberate decision, not a default strategy.
Never Give Aspirin
Aspirin should never be given to children or teenagers with a fever. In the U.S., the FDA recommends avoiding aspirin in anyone under 19 during episodes of fever. It’s linked to Reye’s syndrome, a rare but potentially life-threatening condition that can damage the brain and liver. This applies to any product containing aspirin, including some combination cold medicines, so always check ingredient labels.
Comfort Measures That Help Without Medicine
Medication isn’t always necessary for a fever. If your baby is older than 3 months, is feeding well, and seems reasonably comfortable, you can try non-medication approaches first. Fever itself is part of the body’s immune response, and bringing the number down doesn’t necessarily speed recovery. The goal is comfort, not hitting a specific temperature.
Offer small, frequent sips of breast milk, formula, or an electrolyte solution to prevent dehydration. Babies lose fluids faster when they’re feverish, so more frequent feedings are important even if they’re taking less at each one. Dress your baby in light, breathable clothing. If they have chills, a single blanket is fine, but avoid bundling them up in layers, which traps heat.
A lukewarm bath can help your baby feel more comfortable, but skip cold water or ice baths. Cold water causes shivering, which actually raises the body’s core temperature and makes things worse. Keep the water comfortably warm, not cool, and take your baby out if they seem distressed.
Quick Reference by Age
- Under 2 months: No medication. Any fever of 100.4°F or higher is an emergency room visit.
- 2 to 3 months: Call your pediatrician immediately for any fever of 100.4°F or higher. Do not give medication without their guidance.
- 3 to 6 months: Acetaminophen can be used with your doctor’s input on dosing. Ibuprofen is not yet safe.
- 6 months and older: Either acetaminophen or ibuprofen can be used. Dose by weight, not age, and stick with one medication at a time unless your doctor advises otherwise.