What is the role of cyclobenzaprine (muscle relaxant) in treating Temporomandibular Joint (TMJ) pain?

Cyclobenzaprine for TMJ Pain: Not Recommended

Cyclobenzaprine should not be used for chronic TMJ pain, as the 2023 BMJ clinical practice guideline specifically recommends against acetaminophen with or without muscle relaxants for temporomandibular disorders due to uncertain benefits on pain relief and function. 1

Evidence-Based Recommendation Against Use

The most recent and highest quality evidence comes from a 2023 BMJ clinical practice guideline based on systematic review and network meta-analysis, which places "acetaminophen with or without muscle relaxants or NSAIDs" in the conditional recommendations against category for chronic TMJ pain. 1 This means:

• Benefits on pain relief and function are uncertain
• The intervention is associated with harms or burden
• Most informed patients would likely not want this treatment 1

Why Muscle Relaxants Are Not Recommended

The guideline explicitly states that muscle relaxants (including cyclobenzaprine) should only be considered "if no others are suitable, but people would likely not want them." 1 This recommendation is based on:

• Lack of evidence for efficacy in chronic TMJ pain specifically 1
• The 2020 JAGS guideline notes that so-called "muscle relaxants" including cyclobenzaprine "do not directly relax skeletal muscle and have no evidence of efficacy in chronic pain" 1
• Given the potential for adverse effects, these drugs are not favored for chronic pain 1

Limited Research Evidence

While some older research exists on cyclobenzaprine for TMJ:

• A 2002 small study (n=41) showed cyclobenzaprine was statistically superior to placebo for jaw pain upon awakening when combined with self-care and education 2
• However, a 2009 Cochrane review concluded there was insufficient evidence to support cyclobenzaprine use for myofascial pain, identifying only two small studies with 35 total participants receiving the medication 3
• The Cochrane review explicitly stated: "Further high quality RCTs of cyclobenzaprine for treating MP need to be conducted before firm conclusions on its effectiveness and safety can be made" 3

What Should Be Used Instead

First-line treatments strongly recommended: 1, 4

• Jaw exercises and stretching - provides approximately 1.5 times the minimally important difference in pain reduction 4
• Manual trigger point therapy - provides one of the largest reductions in pain severity 4
• Cognitive behavioral therapy - provides substantial pain reduction 4
• Jaw mobilization techniques - improves joint mobility and reduces pain 4

Second-line options if first-line fails: 1, 4

• Manipulation techniques 1, 4
• Acupuncture 1, 4
• Combined jaw exercise with jaw mobilization 4

Clinical Context: When Muscle Relaxants Might Be Considered

The only scenario where cyclobenzaprine might have a limited role is in acute TMJ dislocation when initial reduction attempts fail, where muscle relaxants may help overcome muscle spasm. 5 However, this is a completely different clinical scenario than chronic TMJ pain.

For acute musculoskeletal pain (not TMJ-specific), cyclobenzaprine 5 mg three times daily has shown efficacy in low back and neck pain with muscle spasm, with onset of relief within 3-4 doses. 6, 7 However, this evidence cannot be extrapolated to TMJ pain given the specific guideline recommendations against its use in this condition.

Common Pitfalls to Avoid

• Do not prescribe cyclobenzaprine as first-line or even second-line therapy for chronic TMJ pain 1
• Do not proceed to pharmacological interventions before exhausting conservative physical therapy options 4, 8
• Do not combine NSAIDs with muscle relaxants for TMJ pain, as this specific combination is conditionally recommended against 1
• Do not ignore patient education about self-management strategies, which should be the foundation of treatment 4

Side Effect Profile

If cyclobenzaprine were to be used (which is not recommended), be aware that: 6

• Somnolence and dry mouth are the most common adverse effects
• These effects are dose-related and mild
• Adverse events were the primary reason for treatment discontinuation in clinical trials
• The 5 mg three times daily dose has lower sedation rates than 10 mg three times daily 6