A systematic review and meta-analysis published in The BMJ March 31, 2015, found “strong evidence” that paracetamol (aka, acetaminophen and Tylenol) is not effective for low back pain. The review of randomized controlled trials included over 1600 patients. There was no difference in low back pain relief or disability when comparing acetaminophen to placebo.
Acetaminophen has been the drug of choice for many clinical practice guidelines (see here, here, and here). But acetaminophen is not without its side effects. Three of the trials in this review (that were for osteoarthritis not back pain) measured patients’ liver enzymes looking for signs of damage due to toxicity. Patients taking acetaminophen were nearly 4 times more likely to show abnormal liver function tests compared to those taking placebo.
While acetaminophen is generally considered to be safe enough for over-the-counter distribution, Propublica reported the CDC’s National Hospital Discharge Survey estimates that 33,000 people are hospitalized as a result of acetaminophen poisoning. The FDA has linked as many as 980 deaths annually to medications containing acetaminophen.