Chronic low back pain: intravenous lidocaine performs no better than placebo in a trial

A placebo comparison, alongside shared background treatment

The trial included adults with nonspecific chronic low back pain and features suggestive of nociplastic pain. This classification refers to altered pain processing, but remained probable here. The findings therefore do not apply indiscriminately to all low back pain.

Participants were assigned equally to intravenous lidocaine infusions or saline infusions, administered weekly for four weeks. All also received amitriptyline and performed aerobic exercise.

The question was therefore specific: does lidocaine add anything to this shared care? The trial did not compare lidocaine with no care.

Equivalent pain relief at three months

The primary outcome was the difference in pain intensity between groups at three months, measured on a visual analog scale. The researchers had prespecified an equivalence margin of plus or minus 1.5 units.

The observed difference was 0.24 units, with a 90% confidence interval ranging from −0.33 to 0.81. This interval fell entirely within the predefined margin. The result therefore supports equivalence under the chosen threshold, rather than simply an absence of a statistically significant difference.

Pain improved in both groups. However, this change does not allow the improvement to be attributed separately to exercise, amitriptyline or the contextual effects of care.

A signal for sleep, with more adverse effects

Sleep quality improved more with lidocaine, with a mean between-group difference in change of 1.81 points on the PSQI questionnaire. However, this was a secondary outcome. The abstract does not establish whether this difference represented a noticeable and meaningful benefit for patients.

Continuous measures of functional disability did not differ significantly between groups. Adverse effects were more frequent with lidocaine, although described as mild, transient and self-resolving. Their type and detailed frequency are not provided in the available excerpt.

What this trial changes

These data do not support routinely adding lidocaine infusions to obtain further pain reduction in this population with this treatment regimen. They do not demonstrate that lidocaine is ineffective for all chronic pain.

The conclusion remains limited to one trial of 84 participants and the primary outcome measured at three months. The dossier provides access only to the abstract, not the full text: several methodological elements needed for a complete assessment therefore remain unverified.

What we can take away

In this trial, adding intravenous lidocaine to amitriptyline and aerobic exercise provides no additional pain relief at three months compared with placebo.