Treatment of Viral Myositis
Viral myositis should be treated with supportive care including adequate hydration, pain management with acetaminophen or NSAIDs, and rest, as it is typically a self-limiting condition with excellent prognosis. 1, 2
Diagnosis and Assessment
- Check creatine kinase (CK) levels to assess muscle damage severity
- Consider respiratory virus panel to identify causative virus (commonly influenza A or B)
- Rule out more serious conditions that may require specific treatment:
- Bacterial myositis (requires antibiotics and possible drainage)
- Immune-mediated myositis (may require immunosuppression)
- Rhabdomyolysis (requires aggressive hydration)
Treatment Algorithm
Mild Disease (ambulatory, minimal pain)
- Oral hydration
- Acetaminophen or NSAIDs for pain relief if no contraindications 1
- Rest affected muscle groups
- Monitor for symptom progression
Moderate Disease (difficulty walking, moderate pain)
- Ensure adequate oral hydration
- Pain management with acetaminophen or NSAIDs 1
- Consider antiviral therapy if influenza-associated and within 48 hours of symptom onset
- Monitor CK levels to assess for rhabdomyolysis
- Follow up to ensure resolution
Severe Disease (inability to walk, severe pain, elevated CK)
- Consider hospitalization for IV hydration if oral intake inadequate
- Monitor for rhabdomyolysis (CK >5-10× normal)
- Aggressive hydration if rhabdomyolysis present
- Pain management
- Antiviral therapy if influenza-associated
Special Considerations
- Most cases of viral myositis are self-limiting and resolve within 3-7 days 3, 2
- Extensive laboratory assessment and hospitalization are often unnecessary for uncomplicated cases 2
- Viral myositis most commonly affects children, particularly following respiratory infections 4, 5
- The most common viral cause is influenza (types A and B) 4, 2
- Rhabdomyolysis is the main potential complication requiring monitoring 5
Follow-up
- Clinical follow-up to ensure symptom resolution
- No routine laboratory monitoring needed unless symptoms worsen
- Return precautions for worsening pain, dark urine, or inability to maintain hydration
Common Pitfalls to Avoid
- Unnecessary hospitalization for mild cases that can be managed as outpatients
- Excessive laboratory testing for a self-limiting condition
- Failure to consider antiviral therapy for influenza-associated myositis when within the treatment window
- Missing rhabdomyolysis as a complication requiring more aggressive hydration
- Confusing viral myositis with more serious conditions like bacterial myositis, which requires antibiotics and possible surgical intervention 6, 4