Skeletal Muscle Relaxants for Body Pains During Influenza
No, skeletal muscle relaxants should not be used for body pains during influenza—use acetaminophen or NSAIDs instead for symptomatic relief of myalgias and fever. 1
Recommended Treatment for Influenza-Related Body Pain
The British Infection Society/British Thoracic Society pandemic influenza guidelines explicitly address pain management in influenza patients and recommend:
- Antipyretics and analgesics (acetaminophen or NSAIDs) should be used to keep patients comfortable and manage fever, headache, chest pain, arthralgia, and abdominal pain associated with influenza 1
- These agents help maintain comfort and preserve the ability to cough effectively, which is important for respiratory clearance 1
Why Muscle Relaxants Are Not Appropriate
Lack of Evidence for Acute Viral Myalgias
- Skeletal muscle relaxants have insufficient evidence for efficacy in general pain conditions, with Category D evidence (insufficient) for chronic pain management 1
- The American Society of Anesthesiologists guidelines note that the literature cannot support skeletal muscle relaxants even for chronic pain syndromes 1
Specific Contraindications from Guidelines
- The American Geriatrics Society emphasizes that muscle relaxants should not be prescribed in the mistaken belief that they relieve muscle spasm, as their effects are nonspecific and not actually related to muscle relaxation 2
- Muscle relaxants are only effective for nonspecific musculoskeletal conditions with muscle spasm, not for systemic viral myalgias 3, 4
Significant Safety Concerns
- Muscle relaxants carry high incidence of CNS adverse effects including sedation and dizziness that can significantly impair quality of life 3
- These agents are associated with greater risk for falls, particularly problematic in patients already weakened by influenza 2
- There is documented abuse potential with centrally acting skeletal muscle relaxants, which can be used along with other CNS depressants 5
- Major toxic effects include respiratory depression and coma—particularly dangerous in influenza patients at risk for respiratory complications 5
Clinical Algorithm for Influenza Body Pain Management
First-line therapy:
- Acetaminophen (up to 3-4 grams/day in adults without liver disease) OR
- NSAIDs (ibuprofen, naproxen) if no contraindications 1
Monitor for:
- Adequate fever control
- Ability to maintain hydration
- Respiratory status (oxygen saturation should remain >92%) 1
Avoid:
- Skeletal muscle relaxants (no evidence, significant side effects)
- Combination products that may lead to acetaminophen overdose
- NSAIDs in patients with renal disease, cardiovascular disease, or GI bleeding risk 1
Critical Pitfalls to Avoid
- Do not assume muscle relaxants work for viral myalgias simply because the pain involves muscles—the pathophysiology is inflammatory, not mechanical muscle spasm 2, 3
- Do not prescribe muscle relaxants to influenza patients who may already have respiratory compromise, as these agents cause respiratory depression 5
- Be aware that acetaminophen can be hepatotoxic at dosages >3-4 grams/day and at lower dosages in patients with chronic alcohol use or liver disease 1