Paracetamol doesn’t speed recovery from acute low back pain: Study

Paracetamol did not improve recovery time for people with low back pain, compared to placebo, according to a study published in TheLancet.

Christopher M. Williams, PhD, of the University of Sydney in Australia, and colleagues used 3-arm randomized trials to compare paracetamol taken regularly, to paracetamol taken as-needed, to placebo medication.

“We thought that, as recommended in treatment guidelines, paracetamol needed to be taken regularly to be effective,” Williams said. “However, patients typically only take paracetamol whenever they need pain relief so we wanted to test the difference between regular doses and as needed doses, in addition to assessing if paracetamol worked for back pain overall compared to placebo.”

To test these hypotheses and ensure adequate blinding of participants, assessors and clinicians, the researchers used a double dummy placebo-controlled design, which means every patient had 2 different tablets to take-1 type of tablet to take regularly and 1 type to take as needed for pain relief. In one group the regular tablets contained real paracetamol and the as-needed tablets were placebo. In the next group the as-needed tablet contained real paracetamol and the regular tablets were placebo tablets, and in the third group both sets of tablets were placebo.

“We asked the participants to take the tablets until they recovered or for a maximum of 4 weeks and asked them to record their pain every day,” Williams said. “We followed them for 3 months.”

The researchers found the pain intensity and a range of other relevant measures, such as patient’s physical function was not different between the treatment groups.

Study participants recovered relatively quickly from their back pain, despite no effect of paracetamol, according to Williams.

“We think that was because they all received good advice to remain active, avoid bed rest and were reassured they will recover,” he said. “Unfortunately, we also know many patients usually miss out from this aspect of care. We think it is very important this is provided to patients. Our findings show we should consider downgrading the contribution of pain relief medicines in helping people manage their low back pain. Instead the emphasis of treatment should be on reassurance and advice to remain active.”

This study was a follow-up to a trial published in The Lancet in 2007. The results of the previous trial showed adding other treatments to the guideline recommended treatments-advice, reassurance and regular paracetamol-did not speed recovery or improve low back pain symptoms.

“Because the patients studied recovered faster than expected overall, we hypothesised that taking paracetamol regularly was helping with the recovery,” Williams said. “While guidelines recommend regular paracetamol as the first choice analgesic for low back pain, this is actually only based on indirect evidence-that is, in patients with low back pain, paracetamol has only been compared to other medicines. So, previously there was no direct evidence about the efficacy of paracetamol in patients with back pain.”

Paracetamol taken either regularly or as-needed did not speed recovery from acute low back pain or affect pain relief compared to placebo, Williams reiterated.

“This tells us 2 things. First, in addition to good advice and reassurance from a doctor, pain medications don’t seem to have much benefit,” he said. “Second, as paracetamol works to relieve pain for a range of conditions, such as headaches, toothache and for pain after surgery, the mechanisms of back pain are likely to be different from other pain conditions, and this is an area that we need to study more.”