Low back pain is the leading cause of disability worldwide, and osteoarthritis of the hip or knee is the 11th highest contributor to global disability.  A new study found paracetamol is ineffective in reducing pain, disability or improving quality of life for patients who suffer from low back pain or osteoarthritis of the hip or knee, and its use may affect the liver.

Paracetamol is currently recommended by most international clinical guidelines as a first line treatment for low back pain and osteoarthritis but it is no better at treating low back pain than a placebo and its effect on osteoarthritis of the hip or knee is too small to be clinically worthwhile, the study concludes.

Lead author, Gustavo Machado of The George Institute and the University of Sydney says the results of this systematic review provide cause to look at guidelines that endorse paracetamol for back pain and osteoarthritis. "World-wide, paracetamol is the most widely used over-the counter medicine for musculoskeletal conditions so it is important to reconsider treatment recommendations given this new evidence. Use of paracetamol for low back pain and osteoarthritis was also shown to be associated with higher risk of liver toxicity in patients. Patients were nearly four times more likely to have abnormal results on liver function tests compared to those taking placebo pills."

Senior author Associate Professor Manuela Ferreira of the George Institute for Global Health and the University of Sydney says there is increasing evidence questioning conventional treatments for back pain and other musculoskeletal conditions. "For example, last year The George Institute showed that paracetamol does not speed recovery or reduce pain for acute low back pain. This latest research, the most comprehensive systematic review of its kind, reaffirms this with an even larger, global patient base, and has for the first time also established that the effects of paracetamol for knee and hip osteoarthritis are too small to be of clinical importance.

"We are also seeing increasing evidence examining early medical imaging for low back pain, which can cost up to $220 million a year in Australia, that shows that this procedure isn't always necessary. We urgently need to take stock of the evidence for common musculoskeletal conditions, a largely under-recognized health priority, and make sure people are receiving appropriate care."

Osteoarthritis expert, Professor David Hunter of the University of Sydney says this new research demonstrates the importance of reviewing paracetamol guidelines for treating osteoarthritis.

"A separate study published recently has shown that paracetamol can be associated with an increasing incidence of mortality and increased risk of cardiovascular, gastrointestinal and renal disease in the general adult population," says Professor Hunter. "Clinicians should carefully weigh benefits and harms when making treatment decisions. Paracetamol is not efficacious and potentially harmful. In this context we cannot justify its continued use for these prevalent diseases."

Land or water-based aerobic exercise, strengthening exercise, weight management and oral or topical anti-inflammatory medicines have been shown to provide benefit for patients with lower limb osteoarthritis, they say.

Published in the British Medical Journal.