Muscle Relaxants for Shoulder Pain
For typical shoulder pain, muscle relaxants are not recommended as they lack evidence of benefit and carry significant risks of sedation and dizziness. Instead, prioritize NSAIDs combined with physical therapy as first-line treatment 1, 2.
Why Muscle Relaxants Are Not Appropriate for Shoulder Pain
The evidence base does not support muscle relaxant use for shoulder conditions:
No proven efficacy: Muscle relaxants (including benzodiazepines like diazepam and non-benzodiazepines) have not demonstrated benefit for shoulder pain in controlled trials 3.
Significant adverse effects: Even short-term use (24 hours to 2 weeks) causes drowsiness and dizziness with a number needed to harm of only 3 patients 3. This means for every 3 patients treated, 1 will experience problematic side effects.
Wrong mechanism: Shoulder pain typically originates from rotator cuff pathology, impingement, or inflammation—not muscle spasm 4, 5. Muscle relaxants target spasticity or spasm, which is not the primary pathology in most shoulder disorders.
Recommended Treatment Algorithm for Shoulder Pain
First-Line Pharmacological Management
Start with NSAIDs: Oral NSAIDs (such as ibuprofen) or topical NSAIDs provide pain relief and address the inflammatory component 1, 2, 6.
Add acetaminophen: Can be combined with NSAIDs for additional analgesia 1, 7.
Consider short-course oral corticosteroids: For cases with significant inflammation, use 30-50 mg daily for 3-5 days, then taper over 1-2 weeks 2, 7.
Essential Physical Therapy Component
Exercise therapy is the cornerstone of shoulder pain management and has the strongest evidence base 8, 5:
Gentle stretching and mobilization focusing on external rotation and abduction 2, 7.
Progressive strengthening of rotator cuff and scapular stabilizers 2.
Exercise alone shows benefit for rotator cuff disease with relative risk of 7.74 for short-term recovery 5.
Interventional Options When Conservative Treatment Fails
Subacromial corticosteroid injection: Provides short-term pain relief to facilitate physical therapy participation 2, 7.
Suprascapular nerve block: Effective for up to 12 weeks for persistent shoulder pain 7.
Special Consideration: Tizanidine
If you are specifically considering tizanidine (the only muscle relaxant with some evidence in musculoskeletal pain):
Tizanidine is FDA-approved for spasticity, not shoulder pain 9.
Major safety concerns include hypotension (two-thirds of patients experience 20% BP reduction at 8 mg dose), hepatotoxicity (5% develop elevated liver enzymes, with rare fatal hepatic failure), and sedation (48% report sedation, 10% severe) 9.
Requires liver function monitoring at baseline, 1,3, and 6 months 9.
Should not be used with antihypertensive medications or other alpha-2 agonists 9.
Critical Pitfalls to Avoid
Do not prescribe muscle relaxants for routine shoulder pain: The risk-benefit ratio is unfavorable with no demonstrated efficacy and significant CNS side effects 3.
Do not use overhead pulley exercises: These can worsen impingement and delay recovery 7.
Do not delay physical therapy: Exercise is more effective than passive modalities and should begin early 8, 5.
Assess for neuropathic features: If sensory changes, allodynia, or hyperpathia are present, use neuromodulating medications (amitriptyline, gabapentin) rather than muscle relaxants 1, 7.