What muscle relaxant is recommended for a shoulder sprain?

Muscle Relaxants for Shoulder Sprain

Direct Answer

Muscle relaxants are NOT recommended for shoulder sprains, as they lack evidence of efficacy for chronic musculoskeletal pain and carry significant risks of adverse effects including sedation, dizziness, and falls. 1

First-Line Treatment Approach

Start with NSAIDs or acetaminophen combined with immediate physical therapy focusing on external rotation and abduction exercises. 2, 3

Pharmacological Management

• Topical NSAIDs should be the first-choice treatment due to superior safety profile while maintaining pain relief efficacy 2
• If topical treatments are insufficient, acetaminophen (up to 4 g/day) is the preferred oral analgesic 2
• Oral NSAIDs (ibuprofen, naproxen) may be used at the lowest effective dose if acetaminophen is inadequate 2, 3

Physical Therapy (Must Be Initiated Immediately)

• Active, active-assisted, or passive range of motion exercises should begin immediately, emphasizing external rotation and abduction movements 2, 3
• External rotation is the single most critical factor in preventing and treating shoulder pain 3
• Local heat application (paraffin wax, hot packs) before exercise provides symptomatic relief 2

Why Muscle Relaxants Are Not Appropriate

The so-called "muscle relaxants" (methocarbamol, carisoprodol, chlorzoxazone, metaxalone, cyclobenzaprine) do not directly relax skeletal muscle and have no evidence of efficacy in chronic pain. 1

Specific Concerns

• These agents are approved only for acute musculoskeletal pain (not sprains specifically) and only for short-term use (2-3 weeks maximum) 4, 5
• Cyclobenzaprine is structurally identical to amitriptyline and carries similar adverse effects including significant sedation 4, 5
• All muscle relaxants are associated with greater risk for falls, particularly concerning in any patient with mobility issues 4
• The most common adverse events are somnolence and dry mouth, which are dose-related 5, 6

Second-Line Options (If First-Line Fails)

Injectable Therapies

• Intra-articular corticosteroid injections (triamcinolone) provide significant pain relief, particularly in acute inflammatory phases 3
• Subacromial corticosteroid injections may be used when pain relates to subacromial inflammation 2, 3
• Botulinum toxin injections into subscapularis and pectoralis muscles can be considered when pain relates to spasticity 2, 3

When Actual Muscle Spasm Is Present

• Baclofen is the preferred agent if true muscle spasm (rather than nonspecific muscle pain) is suspected, starting at 5 mg three times daily with gradual titration 4
• Tizanidine is an emerging alternative with evidence for improved pain control, though primarily studied in perioperative settings 4, 7

Critical Pitfalls to Avoid

• Avoid overhead pulley exercises as they carry the highest risk of worsening shoulder pain 2, 3
• Avoid shoulder immobilization, arm slings, or wraps as these promote frozen shoulder development 3
• Do not delay treatment initiation as this leads to further motion loss and potential permanent dysfunction 3
• Never prescribe benzodiazepines for musculoskeletal pain as they provide no direct analgesic effects and carry high risk profiles 4, 8

Important Clinical Caveats

• If formal physical therapy is not initiated by 6-8 weeks post-injury, permanent shoulder dysfunction may result 3
• In patients with increased gastrointestinal risk, use non-selective NSAIDs with gastroprotective agents or selective COX-2 inhibitors 2
• In patients with increased cardiovascular risk, COX-2 inhibitors are contraindicated and non-selective NSAIDs should be used with caution 2
• Muscle relaxants should be limited to 2-3 weeks maximum if used at all, as effectiveness beyond 4 months has not been assessed 4