MUSCLE RELAXANTS DON’T HELP CHRONIC PAIN

Most chronic pain is the result of an insult, or two, to the musculoskeletal system. A failed surgery on the neck or low back; a fractured hip that was operated but didn’t heal as quickly as expected; an ankle injured many years ago that is now arthritic and hurts with weight-bearing; the shingles rash that healed but still burns and aches, or the fibromyalgia patient whose pain is unexplainable and uncontrollable. These situations all beg for relief, and doctors prescribe multiple drug combinations to rid the patient of their discomfort.

Many of these treatments for chronic pain contain skeletal muscle relaxants in addition to anti-inflammatories, tricyclic, SSRI, or SNRI antidepressants, or anti-convulsants. These drugs are mixed and matched until a combination is found that reduces pain. The question posed in this blog is derived from an article I read recently. It asks if the addition of skeletal muscle relaxants provides better relief than placebo. 

A government-funded study reviewed nine skeletal muscle relaxants studied in 44 different articles. The most studied muscle relaxants were baclofen, tizanidine (Zanaflex), and cyclobenzaprine (Flexeril). Skeletal muscle relaxants “were no better than placebo for lower back pain, fibromyalgia, and headaches.” Skeletal muscle relaxants did, however, cause “significant improvement in nocturnal leg cramps, trigeminal neuralgia (facial sensory nerve pain), and chronic neck pain.” 

BOTTOM LINE: The skeletal muscle relaxants studied did not outperform placebo for major pain syndromes, ie. lower back pain, fibromyalgia, headaches. Other pain syndromes were helped, ie. trigeminal neuralgia, nocturnal leg cramps, neck pain. Most skeletal muscle relaxants cause sedation and drowsiness, which is in some ways detrimental but may actually be the mechanism by which relaxants help the syndromes they help. I used cyclobenzaprine a lot, especially for fibromyalgia. It seemed like it helped at the time. 

Reference: POEMs: Patient-Oriented Evidence That Matters. “Inconsistent Benefit vs Harm of Skeletal Muscle Relaxants for Chronic Pain Syndromes. Am Fam Phys 2025 March;111(3):281-282.