When your baby or toddler has a fever, the first thing most parents reach for is a fever reducer. But with two common options-acetaminophen and ibuprofen-how do you know which is safer, more effective, or right for your child? It’s not just about lowering the number on the thermometer. It’s about doing it safely, correctly, and without making things worse.

What’s the difference between acetaminophen and ibuprofen?

Acetaminophen (also called paracetamol) and ibuprofen are both fever reducers and pain relievers, but they work differently in the body. Acetaminophen mainly affects the brain’s temperature control center. Ibuprofen, on the other hand, reduces inflammation and blocks chemicals that cause pain and fever throughout the body. That’s why ibuprofen often works better for earaches, teething pain, or sore muscles-conditions where swelling plays a role.

For fever alone, studies show ibuprofen lowers temperature more reliably. One major review of 85 studies found that at the four-hour mark, kids treated with ibuprofen were nearly twice as likely to be fever-free compared to those given acetaminophen. The difference isn’t huge for every child, but it’s consistent across multiple trials.

Age limits matter-especially under two

The American Academy of Pediatrics (AAP) doesn’t recommend acetaminophen for babies under three months unless a doctor says so. For ibuprofen, the cutoff is six months. Why? Because very young infants have immature kidneys and livers. Their bodies can’t process these medicines the same way older kids can. Giving them too much, or even the right amount at the wrong time, can lead to serious side effects.

If your baby is under three months and has a fever of 100.4°F (38°C) or higher, call your pediatrician immediately. Fever in newborns can be a sign of something serious like a bacterial infection. Don’t wait to give medicine-get medical advice first.

Dosing by weight, not age

One of the biggest mistakes parents make? Dosing by age. A 15-pound baby and a 20-pound toddler might both be labeled as “6-11 months,” but their medicine needs are completely different. The correct dose for acetaminophen is 7-15 mg per kilogram of body weight every 4-6 hours. For ibuprofen, it’s 4-10 mg per kilogram every 6-8 hours.

Here’s a real example: A 12-pound (5.4 kg) baby needs about 40-80 mg of acetaminophen per dose. That’s roughly 1.25 mL of the infant drops (160 mg/5 mL). But if you guess and give 2.5 mL thinking “it’s for a 10-pound baby,” you’re giving nearly double the safe dose. That’s how accidental overdoses happen.

Always use the measuring device that comes with the bottle. Never use a kitchen spoon. The FDA required all pediatric liquid medications to include calibrated dosing tools in 2020-and for good reason. A 2021 audit from a children’s hospital found that 68% of dosing errors were due to parents using spoons or syringes from other bottles.

Which one works better?

For fever: Ibuprofen wins. Studies show it reduces fever faster and keeps it down longer. One study found kids on ibuprofen stayed fever-free for up to two more hours than those on acetaminophen.

For pain: It’s close. Both help with teething, earaches, and injuries. But if your child has swollen gums or a sprained ankle, ibuprofen’s anti-inflammatory effect gives it an edge. For simple headaches or mild discomfort, acetaminophen works just fine.

Here’s what parents report: On parenting forums, 78% say ibuprofen brings down fevers more effectively. But 32% also mention stomach upset, especially if given on an empty stomach. Acetaminophen is gentler on the tummy-no surprise there.

Safety risks you can’t ignore

Both medicines are safe when used right. But wrong use? That’s where the danger lies.

Acetaminophen: Too much can cause liver damage. The maximum daily dose for kids is 75 mg per kilogram. That sounds like a lot-but it’s easy to hit by accident. Many cold and flu mixes for kids also contain acetaminophen. If you give one of those along with Tylenol, you’re doubling up. A 2021 study found that 29% of acetaminophen-related liver injuries in kids under six came from hidden ingredients in combination products.

Ibuprofen: Too much can stress the kidneys, especially if the child is dehydrated. That’s why you shouldn’t give it if your child hasn’t had fluids in hours or has vomiting or diarrhea. Also, never give ibuprofen to a child with chickenpox-it can increase the risk of a rare but dangerous skin infection.

And here’s something most parents don’t know: Some research links early acetaminophen use (especially in the first year) to a higher chance of developing asthma later. A 2022 meta-analysis found a 1.6 times higher risk. It’s not a guarantee-but it’s a reason to use it only when needed, not as a daily preventive.

Alternating meds? Don’t do it without a doctor

Many parents swear by alternating acetaminophen and ibuprofen every few hours to keep fever down. It sounds smart. But it’s risky. You’re doubling the chance of giving the wrong dose, mixing up timing, or accidentally overdosing. A 2023 AAP study found that alternating didn’t significantly improve fever control compared to using one medicine correctly.

Plus, if you’re alternating, you’re giving medicine every 3-4 hours. That’s a lot. Kids don’t need constant fever reduction. They need rest, fluids, and comfort. If fever is still high after 48 hours, or if your child seems worse, it’s time to see a doctor-not give more medicine.

What about brand names vs. generics?

Children’s Tylenol, Children’s Motrin, Advil, and generics-all contain the same active ingredients. The difference? Price and flavor. Generics make up 76% of sales. They’re just as safe and effective. Save your money. Just make sure the concentration is right: infant drops are 160 mg per 5 mL. Don’t use adult liquid or tablets. Ever.

Also, check the expiration date. Old medicine doesn’t break down into poison, but it loses strength. A 2023 study found that 40% of home medicine cabinets had expired pediatric doses. If it’s more than a year past the date, toss it.

What to do when the fever won’t break

Medicine isn’t the only tool. Dress your child in light clothes. Keep the room cool. Offer fluids often-even small sips help. A lukewarm bath can feel soothing, but never use ice water or alcohol rubs. Those can cause shivering, which raises body temperature even more.

If your child is under 2, and the fever lasts more than 48 hours, or if they’re lethargic, not eating, crying nonstop, or have a rash, call your doctor. Fever is a symptom, not the enemy. The real goal is to help your child feel better, not to chase a number.

What’s changing in 2025?

The AAP is updating its fever guidelines in January 2025. New data on acetaminophen and asthma risk, plus more research on ibuprofen use in infants under six months, will shape the next version. For now, stick with the current advice: use the right dose, by weight, and only when necessary.

Also, new dosing apps and smart syringes are hitting the market. Some connect to your phone and remind you when to give the next dose. They’re not necessary-but if you’re confused or anxious, they can help reduce mistakes.

Bottom line: Choose wisely, dose accurately

For most kids over six months, ibuprofen is the better choice for fever and pain. It works faster, lasts longer, and helps with inflammation. For babies three months and older, acetaminophen is still a solid, gentler option-especially if they have stomach sensitivity or are dehydrated.

But here’s the real rule: Always dose by weight, never by age. Use the right tool. Never mix meds unless your doctor says so. And when in doubt, call your pediatrician.

Fever is scary. But with the right info, you’re not powerless. You’re a parent who knows how to help-without risking more harm than good.