There are many common medical practices that have surprisingly little evidence to back them up. It turns out that taking acetaminophen (Tylenol) for lower back pain is one of them. Studies have shown that while lower back pain is the leading cause of disability worldwide and many people rely on painkillers like Tylenol, it appears that they are basically useless. In a study of 1,600 patients over a three-month period, acetaminophen did absolutely nothing to alleviate lower back pain. There is some evidence that applying heat or spinal manipulation through physical therapy may help. The worst thing you can do is stay in bed. Patients are encouraged to stay active and expect to see some relief within two weeks.