Australian researchers have found widely prescribed muscle relaxants are ‘largely ineffective and potentially unsafe’ when treating low back pain.
The team Neuroscience Research Australia and University of NSW reported ‘muscle relaxants might reduce pain in the short term, but the effect is too small to be considered clinically meaningful, and there is an increased risk of side effects’.
Their research, published in the British Medical Journal, also noted the ‘effects of long-term muscle relaxant use remain unknown’.
The team noted recommended treatments for low back pain – a major global public health problem and leading cause of disability worldwide for the past 30 years – are unclear and often conflicting; but despite scientific uncertainty, muscle relaxants are the third most frequently prescribed drugs for low back pain.
To investigate effectiveness of muscle relaxants, including nonbenzodiazepine antispasmodics, researchers reviewed evidence from 31 randomised controlled trials – involving over 6,500 participants published as recently as February 2021 – to assess whether they were:
- effective (successfully reduced pain intensity and alleviated disability);
- acceptable (whether the drug was discontinued for any reason); and
- safe (whether the participant experienced drug-related adverse events).
UNSW’s Professor James McAuley said the results showed a ‘high level of uncertainty around the clinical efficacy and safety of muscle relaxants as a treatment for low back pain’.
He summed up: ‘We found muscle relaxants might reduce pain in the short term, but on average the effect is probably too small to be important and most patients wouldn’t be able to feel any difference in their pain compared to taking a placebo.
There is also an increased risk of side effects (commonly dizziness, drowsiness, headache and nausea). ‘We were surprised by this finding, as earlier research suggested muscle relaxants did reduce pain intensity. But when we included all the most up-to-date research, the results became much less certain.’
The researchers suggested large, high quality, placebo-controlled trials ‘are urgently needed to resolve uncertainties in the evidence for the efficacy and safety of muscle relaxants for low back pain’. AMP
