New study says muscle relaxants add no short-term benefit for acute low back pain

A recent study has shown that there is no short-term extra benefit when muscle relaxants are added to ibuprofen (i.e. Advil) for acute low back pain.

Government-funded (US) researchers wanted to know if treatment for acute low back pain - of 2 weeks' duration or less (average 72 hours) - was more effective with a combination of ibuprofen and a muscle relaxant as compared with ibuprofen alone to improve functional outcomes and reduce pain. They enrolled 320 patients who presented to 1 of 2 emergency departments with complaint of low back pain, not involving spinal nerves.

All patients were given ibuprofen 600 mg to be taken up to 3 times a day, as needed. They were also randomized, concealed allocation unknown, to receive identical-appearing capsules containing placebo, baclofen 10 mg, metaxalone 400 mg, or tizanidine 2 mg, and were instructed to take 1 or 2 capsules up to 3 times a day, as needed. One week later, approximately 34% of patients across the groups reported moderate to severe back pain.

Bottom line

Adding a muscle relaxant to treatment with ibuprofen does not improve functional outcomes or pain, or lessen the number of people reporting moderate to severe back pain one week after starting treatment.

Reference

Friedman BW, Irizarry E, Solorzano C, et al. A randomized, placebo-controlled trial of ibuprofen plus metaxalone, tizanidine, or baclofen for acute low back pain. Ann Emerg Med 2019;74(4):512-520.