Analgesic medication is the most frequently prescribed treatment for low back pain
(LBP), of which paracetamol (acetaminophen) is recommended as the first choice medication.
However, there is uncertainty about the efficacy of paracetamol for LBP. To investigate
the efficacy and safety of paracetamol for non‐specific LBP. We conducted searches
on the Cochrane Central Register of Controlled Trials (CENTRAL, which includes the
Back and Neck Review Group trials register), MEDLINE, EMBASE, CINAHL, AMED, Web of
Science, LILACS, and IPA from their inception to 7 August 2015. We also searched the
reference lists of eligible papers and trial registry websites (WHO ICTRP and ClinicalTrials.gov).
We only considered randomised trials comparing the efficacy of paracetamol with placebo
for non‐specific LBP. The primary outcomes were pain and disability. We also investigated
quality of life, function, adverse effects, global impression of recovery, sleep quality,
patient adherence, and use of rescue medication as secondary outcomes. Two review
authors independently performed the data extraction and assessed risk of bias in the
included studies. We also evaluated the quality of evidence using the GRADE approach.
We converted scales for pain intensity to a common 0 to 100 scale. We quantified treatment
effects using mean difference for continuous outcomes and risk ratios for dichotomous
outcomes. We used effect sizes and 95% confidence intervals as a measure of treatment
effect for the primary outcomes. When the treatment effects were smaller than 9 points
on a 0 to 100 scale, we considered the effect as small and not clinically important.
Our searches retrieved 4449 records, of which two trials were included in the review
(n=1785). For acute LBP, there is high‐quality evidence for no difference between
paracetamol (4 g per day) and placebo at 1 week (immediate term), 2 weeks, 4 weeks,
and 12 weeks (short term) for the primary outcomes. There is high‐quality evidence
that paracetamol has no effect on quality of life, function, global impression of
recovery, and sleep quality for all included time periods. There were also no significant
differences between paracetamol and placebo for adverse events, patient adherence,
or use of rescue medication. No trials were identified evaluating patients with subacute
or chronic LBP. We found that paracetamol does not produce better outcomes than placebo
for people with acute LBP. Paracetamol for low back pain Review question To see how
well paracetamol works for non‐specific low back pain (LBP). Non‐specific LBP is back
pain for which there is no identified disease or condition. Background Paracetamol
is one of the most commonly prescribed medicines for people with LBP, and it is recommended
in the guidelines that are issued to help doctors manage different illnesses. However,
recent evidence has called into question how effective it is. Search date The evidence
is current to August 2015. Study characteristics We included two trials with a total
of 1785 participants in this review with participants whose back pain occurred suddenly
and recently (acute). Most of the people in the study (90%) were middle‐aged and came
from a single trial that looked at acute back pain. Both trials tested paracetamol
against a placebo (which contains nothing that could act as a medicine). Participants
were followed between one day and 12 weeks. The main outcomes we studied were pain
and disability; we also looked at quality of life, how easily people could go about
their daily lives, unpleasant or unwanted side effects, how well people felt they
had recovered, sleep quality, whether participants had taken the medicine as prescribed,
and if it had been necessary to take ‘rescue medication’ because the paracetamol had
not worked. We combined the findings from one trial (n=1651) into a single analysis
(meta‐analysis) that compared paracetamol to a placebo; the second trial did not report
the results for the placebo, and so it could not be included. Key results and quality
of evidence We found high‐quality evidence that paracetamol (4 g per day) is no better
than placebo for relieving acute LBP in either the short or longer term. It also worked
no better than placebo on the other aspects studied, such as quality of life and sleep
quality. About one in five people reported side effects, though few were serious,
and there was no difference between intervention and control groups. As most of the
participants studied were middle‐aged, we cannot be sure that the findings would be
the same for other age groups.