For babies under 6 months, Tylenol (acetaminophen) is the only option. Motrin (ibuprofen) is not recommended until 6 months of age due to risks to the kidneys and digestive system. Once your baby is old enough for either, both are safe and effective, but each has situations where it works better than the other.
Why Age Matters for Choosing
Tylenol can be given from birth, with doses available for babies as small as 6 pounds. Motrin, on the other hand, is off-limits until at least 6 months old. This isn’t just a conservative guideline. Young infants face real risks from ibuprofen, including kidney problems, serious gastrointestinal side effects, and a higher chance of dangerous infections. So for newborns and young babies dealing with fever after vaccinations or general fussiness, Tylenol is your go-to by default.
Once your baby hits 6 months and weighs at least 12 pounds, both medications become options. That’s when the choice gets more nuanced.
How They Work Differently
Tylenol reduces fever and relieves pain, but it doesn’t fight inflammation. Motrin does both. It blocks the production of chemicals in the body that cause swelling, pain, and fever. This anti-inflammatory effect is what gives Motrin an edge in certain situations, particularly when pain involves swollen gums, ear infections, or other inflammation-driven discomfort.
The duration of relief also differs. Tylenol can be given every 4 hours, while Motrin lasts longer and is dosed every 6 hours. For overnight comfort, Motrin’s longer window can mean fewer wake-ups for both you and your baby.
Which Works Better for Fever
Clinical evidence is mixed but leans slightly toward Motrin for fever reduction. A large meta-analysis of pediatric studies found that about half concluded ibuprofen was more effective than acetaminophen for lowering fever, while the other half found no significant difference. When researchers pooled the data, ibuprofen produced measurably lower fever scores at the four-hour mark after a dose. The difference was modest, not dramatic, but it was consistent.
In practice, this means both drugs will bring a fever down. But if your baby is 6 months or older and running a higher fever, Motrin may get them more comfortable a bit faster and keep them that way longer between doses.
Which Is Better for Teething
Most pediatricians recommend either acetaminophen or ibuprofen for teething pain, and about 80 percent of primary care doctors suggest one or the other as a first-line approach. Because teething involves inflamed, swollen gums, Motrin’s anti-inflammatory properties give it a practical advantage here. It targets the swelling that’s causing the pain, not just the pain itself. For babies 6 months and older who are clearly struggling with teething, many parents find Motrin provides more noticeable relief.
Safety and Side Effects
Both medications are safe at recommended doses, but they carry different risks when something goes wrong.
Tylenol’s main danger is to the liver. At correct doses, it’s very well tolerated. But overdoses, even modest ones from accidentally doubling up or using multiple products that contain acetaminophen, can overwhelm the liver’s ability to process a toxic byproduct of the drug. This can lead to serious liver damage. The risk is real enough that you should always check the active ingredients on any other medications your baby is taking to avoid accidentally stacking acetaminophen.
Motrin’s risks center on the stomach and kidneys. Ibuprofen can irritate the digestive tract and, in rare cases, cause ulcers or gastrointestinal bleeding. It can also strain the kidneys, especially in a child who is dehydrated. A 2023 study found that kidney injury from ibuprofen can occur even at normal doses in dehydrated children. This is important because babies with fever are often not drinking well. If your baby has a stomach bug, is vomiting, or has had diarrhea, Tylenol is the safer choice.
Motrin should also be avoided in a few specific situations: chickenpox, suspected sinus infections, and respiratory illnesses where pneumonia is a concern. Research suggests ibuprofen may worsen bacterial and viral infections, particularly skin infections. When in doubt during an active illness, Tylenol carries fewer of these infection-related risks.
Getting the Dose Right
Both medications are dosed by weight, not age. Age ranges on the box are rough guides, but your baby’s actual weight determines the correct amount. Here are the infant ranges for the standard liquid concentrations:
Tylenol (every 4 hours):
- 6 to 11 lbs: 1.25 mL
- 12 to 17 lbs: 2.5 mL
- 18 to 23 lbs: 3.75 mL
Motrin (every 6 hours, 6 months and older only):
- 12 to 17 lbs: 1.25 mL
- 18 to 23 lbs: 1.875 to 2.5 mL
One important detail: liquid acetaminophen used to come in a more concentrated “infant drops” formula (80 mg per 0.8 mL) that was different from the children’s version (160 mg per 5 mL). The FDA pushed manufacturers to standardize to the less concentrated children’s formula for infant products too, but not all brands made the switch at the same time. Always check the concentration printed on the bottle you have and use the syringe that came with it.
Should You Alternate Both?
You may have heard about alternating Tylenol and Motrin every few hours to keep fever under control. While some parents and even some doctors use this approach, the American Academy of Pediatrics has advised against routinely alternating or combining the two. The concern is twofold: it increases the chance of a dosing error, and there’s a theoretical risk that using both together raises the potential for liver and kidney toxicity.
Case reports have documented reversible kidney failure in children who received both drugs at normal doses. The risk hasn’t been proven in large studies, but the evidence for safety with repeated alternating use is also lacking. The recommended approach is to use one medication at the correct dose and interval first. If a single drug isn’t controlling your baby’s discomfort, short-term alternating may be considered, but that’s a conversation to have with your pediatrician rather than a routine strategy.
A Quick Guide to Choosing
- Under 6 months: Tylenol only.
- Fever in a well-hydrated baby over 6 months: Either works. Motrin may be slightly more effective and lasts longer.
- Teething pain: Motrin has an edge because it reduces gum inflammation.
- Vomiting, diarrhea, or dehydration: Tylenol, because ibuprofen can harm the kidneys when fluid levels are low.
- Chickenpox or skin infections: Tylenol, because ibuprofen may worsen these conditions.
- Overnight comfort: Motrin lasts 6 hours versus Tylenol’s 4.