Taking common painkillers for a bad back may do more harm than good, warns new research. Scientists say their findings raise “considerable uncertainty” around the effectiveness and safety of popping pills for back pain.
They found that painkillers can trigger unpleasant side-effects - such as nausea, dizziness and headaches - while having only limited impact on reducing the original discomfort. The Australian research team advised patients and doctors to take a "cautious" approach to the use of painkillers such as paracetamol and ibuprofen.
They conducted an in-depth analysis of almost 60 years of research into the prescription of pills for back pain. But their findings, published by The BMJ, show there is still a lack of "high certainty evidence" on the effectiveness and safety of commonly used painkillers, known as analgesics, for short bouts of lower back pain. Study lead author Dr Michael Wewege said that until higher quality trials comparing analgesics with each other are published, GPs and patients were advised to take a cautious approach to manage acute non-specific low back pain with analgesic medicines.
Dr Wewege, of the University of New South Wales, said: "Analgesics such as paracetamol, ibuprofen, and codeine are widely used to treat acute non-specific low back pain, defined as pain lasting less than six weeks. But evidence for their comparative effectiveness is limited."
To try to fill the knowledge gap, Dr Wewege and his colleagues looked at scientific databases for trials comparing analgesic medicines with another analgesic, placebo, or no treatment in patients reporting acute non-specific low back pain. From an initial 124 relevant trials, they included 98 randomised controlled trials published between 1964 and 2021 in their analysis.
Those trials involved more than 15,100 adult participants and 69 different medicines or combinations. The trials included non-steroidal anti-inflammatory drugs, paracetamol, opioids, anti-convulsant drugs, muscle relaxants and corticosteroids. The researchers assessed their risk of bias using a validated risk tool.
Dr Wewege said: "The main measures of interest were low back pain intensity at the end of treatment - on a zero to 100 point scale - and safety: the number of participants who reported any adverse event during treatment. Average pain intensity among participants at the start of each trial was 65 out of 100."
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The researchers noted low or very low confidence in evidence for reduced pain intensity - around 25 points- after treatment with muscle relaxant tolperisone, anti-inflammatory drug aceclofenac plus muscle relaxant tizanidine, and the anti-convulsant drug pregabalin, compared with placebo. Very low confidence was also noted in evidence for large reductions in pain intensity - around 20 points - for four medicines, such as the muscle relaxant thiocolchicoside and anti-inflammatory drug ketoprofen.
Moderate reductions of 10 to 20 points were seen for seven medicines, including anti-inflammatory drugs aceclofenac, etoricoxib and ketorolac, and small reductions of five to 10 points for three medicines including ibuprofen and paracetamol. Dr Wewege said: "Low or very low confidence evidence suggested no difference between the effects of several of these medications."
The researchers noted moderate to very low confidence evidence for increased adverse events - including nausea, vomiting, drowsiness, dizziness, and headache - with tramadol, paracetamol plus sustained release tramadol, baclofen, as well as paracetamol plus tramadol compared to placebo. Moderate to low confidence evidence also suggested that those medications could increase the risk of adverse events compared to other medications. The study also found similar moderate to low confidence evidence for other secondary outcomes, including serious adverse events and discontinuation from treatment, as well as a secondary analysis of medication classes.
Senior author Professor James McAuley, also of the University of New South Wales, added: “Our review of analgesic medicines for acute non-specific low back pain found considerable uncertainty around effects for pain intensity and safety. As such, clinicians and patients are advised to take a cautious approach to the use of analgesic medicines.”
