Ibuprofen is a monocarboxylic acid that is propionic acid in which one of the hydrogens at position 2 is substituted by a 4-(2-methylpropyl)phenyl group. It has a role as a non-steroidal anti-inflammatory drug, a non-narcotic analgesic, a cyclooxygenase 2 inhibitor, a cyclooxygenase 1 inhibitor, an antipyretic, a xenobiotic, an environmental contaminant, a radical scavenger, a drug allergen and a geroprotector. It is functionally related to a propionic acid. It is a conjugate acid of an ibuprofen(1-).