“Acetaminophen is the most popular pain reliever in the US…a large fraction of users are close to a toxic dose in the ordinary course of use…researchers have found “high quality evidence” that paracetamol (acetaminophen) does not reduce pain intensity or disability, and does not improve quality of life, in the short term for people experiencing low back pain; and provides only “minimal, short term benefit” for people suffering from hip or knee pain caused by OA, stating that “the small effects are not likely to be meaningful for clinicians or patients.”
http://www.dynamicchiropractic.com/mpacms/dc/article.php?id=57383