Acetaminophen (Paracetamol) Minimally Effective for Back Pain and Osteoarthritis

Clinical Question

Is acetaminophen (paracetamol) effective for the treatment of low back pain or osteoarthritis?

Bottom Line

Although acetaminophen was hoped to be a safer alternative to nonsteroidal anti-inflammatory drugs and opioids for the treatment of common musculoskeletal problems, on average it provides only minimal pain relief and improvement in function for patients with low back pain or osteoarthritis. Some persons may benefit with full dosages of acetaminophen but most will not. (Level of Evidence = 1a)

Synopsis

To identify all randomized controlled trials, the authors searched nine databases, including the Cochrane Registry. Two investigators independently selected articles for inclusion and extracted the data. Two investigators evaluated the quality of the 13 research studies, most of which were of good quality. Most of the studies used full dosages of acetaminophen (3,900 to 4,000 mg daily). There was no evidence of publication bias. For patients with low back pain, high-quality research in more than 1,000 patients found a lack of effectiveness on pain and disability in either the immediate (less than two weeks) or short-term (two weeks to three months) follow-up periods. For hip or knee osteoarthritis, acetaminophen produced a statistically significant but clinically unimportant effect on pain and disability over the immediate or short term. The research results were homogeneous except for immediate-term disability. Adverse effects were minimal. Patients receiving acetaminophen were more likely to have higher liver-function test results (greater than 1.5 times normal) than patients receiving placebo.

Study design: Meta-analysis (randomized controlled trials)

Funding source: Self-funded or unfunded

Setting: Various (meta-analysis)

Reference: Machado GC, Maher CG, Ferreira PH, et al. Efficacy and safety of paracetamol for spinal pain and osteoarthritis: systematic review and meta-analysis of randomised placebo controlled trials. BMJ. 2015; 350: h1225.