Are Muscle Relaxants for Low Back Pain Effective?

If you experience lower back pain, you are not alone. According to a systematic analysis for the Global Burden of Disease Study 2017, lower back pain has been the leading cause of disability across the globe for the past 30 years.¹ Muscle relaxants are commonly prescribed to treat low back pain.

Muscle relaxants, including non-benzodiazepine antispasmodics and antispastics, are the third most common drugs that are prescribed for lower back pain, according to multiple studies.^2,3 But there are mixed guidelines regarding the benefit and safety of muscle relaxants for low back pain.⁴

A review published by the BMJ⁴ looked at all available studies that were related to low back pain and treatment with muscle relaxants. Data from 31 studies were included in a meta-analysis – a compilation of data from multiple studies.

The results of the study suggested that within the initial two weeks of treatment, certain muscle relaxants called non-benzodiazepine antispasmodics reduced acute low back pain more than the control group.

What are muscle relaxants?

Muscle relaxants are often prescribed in addition to rest and physical therapy as a result of a muscular injury. They depress the central nervous system and can relax the musculoskeletal system.

What are non-benzodiazepine antispasmodics & antispastics?

Antispasmodics work to reduce muscle spasms.⁵ One classification is non-benzodiazepines, which act on the spinal cord or brain stem of the patient. Some examples include cyclobenzaprine, carisoprodol, and metaxalone. 

Antispastics are often prescribed for conditions including cerebral palsy and multiple sclerosis.⁶  Examples include baclofen and dantrolene.

What advantage do non-benzodiazepine antispasmodics provide for low back pain?

The data for acute back pain suggest that the use of non-benzodiazepine antispasmodics reduces pain compared to a control group within two weeks of treatment. Although these results were statistically significant, they had very low certainty.

From weeks three to thirteen of treatment, there was no significant pain reduction in the treated group versus the control. This suggests that non-benzodiazepine antispasmodics provide an advantage over non-muscle relaxant treatment within a two-week treatment window.

The meta-analysis also showed no decrease in patient disability compared to a control group when non-benzodiazepine antispasmodics were administered.

Do muscle relaxants help chronic low back pain?

Based on the review’s meta-analysis, there was no benefit associated with taking antispastic or miscellaneous muscle relaxants for disability or pain within three to thirteen weeks of treatment.⁴

Are muscle relaxants safe for low back pain?

The review found that taking non-benzodiazepine antispasmodics for acute low back pain is associated with an increased risk for adverse effects, but not serious effects, compared to a control.⁴ These findings were significant but at low and very low certainty, respectively.

There was also evidence that antispastics for acute low back pain elevate the risk for an adverse event while benzodiazepines did not pose the same risk. It was found that patients taking antispastics were more likely to stop taking the drug compared to patients taking non-benzodiazepine antispasmodics due to the adverse effects of treatment.

How will these findings help treat low back pain?

The authors note that their findings, although significant, will not likely affect clinical practice because of low certainty data. They highlight the need for more controlled trials where a placebo versus treatment is used to further determine the benefit and safety of taking muscle relaxants for low back pain.

For now, the authors recommend that patients be made aware of the possible benefits and safety concerns associated with muscle relaxants for low back pain before beginning treatment.

References

1. Global Burden of Disease 2017 Disease and Injury Incidence and Prevalence Collaborators. (2019). Global, regional, and national incidence, prevalence, and years lived with disability for 354 diseases and injuries for 195 countries and territories, 1990-2017: a systematic analysis for the Global Burden of Disease Study 2017. The Lancet; 393(10190): e44. Doi: 10.1016/S0140-6736(18)32279-7.
2. Gore, M. et al. (2012). Use and Costs of Prescription Medications and Alternative Treatments in Patients with Osteoarthritis and Chronic Low Back Pain in Community-Based Settings. Pain Practice; 12(7): 550-560. Doi: 10.1111/j.1533-2500.2012.00532.x.
3. Ivanova JI, Birnbaum HG, Schiller M, Kantor E, Johnstone BM, Swindle RW. Real-world practice patterns, health-care utilization, and costs in patients with low back pain: the long road to guideline-concordant care. Spine J. 2011;11(7):622-632. doi:10.1016/j.spinee.2011.03.017
4. Cashin, A.G. et al. (2021). Efficacy, acceptability, and safety of muscle relaxants for adults with non-specific low back pain: systematic review and meta-analysis. The BMJ; 374: n1446. Doi: 10.1136/bmj.n1446.
5. Jackson MD, Ryan DM. Drugs of Importance in Rehabilitation. In: JA DeLisa editor(s). Rehabilitation Medicine: Principles and Practice. 2. Philadelphia: J.B. Lippincott Company, 1993.
6. See S, Ginzburg R. Choosing a skeletal muscle relaxant. Am Fam Physician. 2008;78(3):365-370. https://www.aafp.org/pubs/afp/issues/2008/0801/p365.html