Infants from 12 to 17 pounds may be given 50mg of ibuprofen every six hours, while those who are 18 to 23 pounds can take up to 75mg, according to WebMD. Giving ibuprofen to babies that weigh less than 12 pounds is not advised without first consulting a doctor.
Once a child weighs at least 96 pounds, they may be given adult doses of ibuprofen, according to WebMD. To avoid the risk of overdose, ibuprofen and acetaminophen should not be alternated, unless directed to do so by a doctor. Additionally, children with aspirin allergies should also not take ibuprofen. A doctor should be consulted prior to use with infants aged three months and younger, who are experiencing a fever unrelated to prior vaccinations, in order to rule out possible underlying conditions.