Which is safer for infants: ibuprofen or acetaminophen?

Ibuprofen: both are really, equally, 99.9%, safe but acetaminophen has a tiny, rare, chance of causing liver damage

Depends: We never give ibuprofen under 6 mo of age because of risks related to the kidneys. After that point they are both about equal in safety & effectiveness when given at proper doses. I prefer ibuprofen since you don't have to give it as often.