Long-term Use of Cyclobenzaprine for Pain: A Review of the Clinical Effectiveness

Key Message

The efficacy and safety of cyclobenzaprine has been assessed in randomized controlled trials (RCTs) and systematic reviews of RCTs for fibromyalgia, back pain, neck pain, myofascial pain, and spasticity. Cyclobenzaprine may be more effective in fibromyalgia and back pain than placebo, however available studies are of limited duration, mostly two weeks or less. RCT results have been inconsistent, and they are not without limitations. Comparative studies of cyclobenzaprine vs amitriptyline in fibromyalgia, and vs diazepam, NSAIDs or other muscle relaxants for musculoskeletal pain, have found similar outcomes between groups. There is no evidence of benefit of cyclobenzaprine in neck pain or myofascial pain. An RCT assessing combination therapy with cyclobenzaprine plus an NSAID or cyclobenzaprine alone for neck pain found no evidence of benefit of combination or monotherapy vs placebo. Adverse events including drowsiness, dizziness and dry mouth occur frequently. There were no economic evaluations or systematic reviews of economic evaluations identified.Evidence-based practice guidelines lack specific recommendations with respect to use of cyclobenzaprine or other medications, reflecting the lack of quality and quantity of available evidence.