Paracetamol (acetaminophen) is ineffective for the treatment of spinal pain and provides negligible benefits for low back pain or osteoarthritis of the hip or knee, its usage also may affect the liver, according to a study published March 31 in BMJ.
Lead study author Gustavo Machado, a PhD student from The George Institute for Global Health at the University of Sydney in Australia, and his research colleagues conducted 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 reduction of pain intensity, improvement of disability, quality of life, safety, and patient adherence were analyzed in this trial.
Gustavo Machado
The study included 13 randomized controlled trials that examined the effects of paracetamol use compared with placebo. Ten 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 that were evaluated for the use of paracetamol for lower back pain.
Among the study’s findings:
• For lower back pain, paracetamol had no effect and did not reduce disability or improve quality of life compared with placebo.
• Paracetamol use for osteoarthritis was shown to increase the likelihood of receiving abnormal results on liver function tests by almost 4 times compared with placebo.
• For osteoarthritis, the researchers found small, but not clinically important benefits in the reduction of pain and disability compared with placebo.
“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,” Mr. Machado stated.
The study also found that adverse side effects varied across all of the trials. But no differences were found in the number of patients using paracetamol reporting these effects or being withdrawn from studies because of adverse events compared with those using a placebo. The adherence to treatment schedule rates was similar among patients taking paracetamol compared with those taking placebo.
“Use of paracetamol for low back pain or osteoarthritis was also shown to be associated with higher risk of liver toxicity in patients," Mr. Machado said. “Patients were nearly 4 times more likely to have abnormal results on liver function tests compared to those taking placebo pills.”
“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,” stated Mr. Machado.