Clinical guidelines recommend paracetamol as the first line drug treatment for both conditions, but the evidence to support this recommendation is weak and inconsistent and there are safety concerns with the recommended full dosage (up to 4000 mg/day).
For these reasons, the recent move by the National Institute for Health and Care Excellence (NICE) to continue to recommend paracetamol for osteoarthritis has been considered controversial.
Lead author Gustavo Machado from The George Institute for Global Health at the University of Sydney carried out a systematic review and meta-analysis to examine the efficacy and safety of paracetamol for lower back pain and osteoarthritis of the hip or knee.
The study included 13 randomised controlled studies that looked at the effects of paracetamol use compared with a placebo: 10 trials included 3,541 patients and evaluated the use of paracetamol for osteoarthritis of the hip or knee, and 3 trials included 1,825 patients on the use of paracetamol for lower back pain.
The study showed that for lower back pain, paracetamol had no effect and did not reduce disability or improve quality of life compared with the use of a placebo. For osteoarthritis, they found small, but not clinically important benefits in the reduction of pain and disability compared with the use of a placebo.
Paracetamol use for osteoarthritis was also shown to increase the likelihood of having abnormal results on liver function tests by almost four times compared with a placebo, but the clinical relevance of this is still not certain, explain the authors.
The authors concluded that "these results support the reconsideration of recommendations to use paracetamol for patients with low back pain and osteoarthritis of the hip or knee in clinical practice guidelines."
The study published in The BMJ.