Paracetamol is ineffective at treating back pain, Australian researchers say.
The painkiller was also found to have "small but not clinically important" benefits for people with osteoarthritis, with experts warning it could increase the risk of liver problems.
The National Institute for Health and Care Excellence (NICE) currently recommends people suffering from with lower back pain and osteoarthritis take the drug.
Researchers at the University of Sydney reviewed data from 13 studies looking at the effects of paracetamol use compared with a placebo.
It found the painkiller was ineffective at dealing with back pain, and did not reduce disability or improve quality of life.
Researchers said their evidence - published in the British Medical Journal - should force a review of whether paracetamol should be recommended to those who suffer from lower back pain and osteoarthritis treat pain.