Treatment of Influenza-Related Myalgia
For myalgia due to influenza, treat with paracetamol (acetaminophen) or ibuprofen at standard doses, combined with rest and adequate hydration, while carefully monitoring patients with asthma for respiratory deterioration. 1
First-Line Symptomatic Management
The British Infection Society and British Thoracic Society explicitly recommend the following approach for influenza-related myalgia:
- Paracetamol or ibuprofen for treatment of fever, myalgias, and headache 1, 2
- Ibuprofen dosing: Start with 400 mg, then 200-400 mg every 4-6 hours as needed, not exceeding 1200 mg daily for over-the-counter use 2
- Rest to reduce metabolic demands 1
- Drinking plenty of fluids to maintain hydration 1
- Avoiding smoking 1
These recommendations have little scientific evidence supporting them, but clinical experience suggests they help and are unlikely to cause harm 1.
Critical Considerations for Asthma Patients
Patients with asthma require heightened vigilance because influenza causes worsening of chronic respiratory conditions:
- Asthma patients are at high risk for influenza-related complications and should be monitored closely 1
- Wheezing or lung crackles occur in approximately 10% of influenza cases and are more common in patients with coexisting chronic lung disease 1
- Productive cough with chest tightness and substernal soreness is more common in patients with underlying chronic lung disease 1
- Influenza infection has been associated with worsening clinical condition in patients with asthma and COPD 1
Antiviral Therapy Integration
While symptomatic treatment addresses myalgia, antiviral therapy is the disease-modifying intervention:
- Oseltamivir 75 mg twice daily for 5 days should be initiated within 48 hours of symptom onset 3
- Antiviral therapy reduces fever and cough duration by 1.5-3 days 2
- High-risk patients (including those with asthma) should receive early antiviral therapy regardless of symptom duration 2, 4
- Oseltamivir demonstrated more rapid cessation of febrile illness in patients with chronic cardiac or respiratory diseases, though it did not reduce time to alleviation of all symptoms 3
Warning Signs Requiring Immediate Reassessment
Instruct patients to seek immediate medical attention for:
- Shortness of breath at rest or with minimal activity 1
- Painful or difficult breathing 1, 2
- Coughing up bloody sputum 1, 2
- Drowsiness, disorientation, or confusion 1, 2
- Fever persisting 4-5 days without improvement or worsening 1, 2
These red flags may indicate complications such as pneumonia, which occurs more frequently and with greater severity in patients with pre-existing chronic respiratory conditions 1.
Specific Pitfalls to Avoid
- Never use aspirin in children or adolescents under 16 years with influenza due to Reye's syndrome risk, a potentially fatal acute encephalopathy with liver dysfunction 1, 2
- Do not withhold antiviral therapy in asthma patients while relying solely on symptomatic treatment with analgesics 2, 4
- Do not dismiss worsening respiratory symptoms as simply part of the flu—pneumonia typically develops 4-5 days after onset and requires antibiotic therapy 1
- Do not assume absence of fever rules out severe disease in elderly or immunocompromised patients, who may not mount adequate febrile responses 4, 5
Clinical Context for Myalgia
Myalgia in influenza typically affects the back and limbs and is one of the cardinal symptoms occurring in approximately 53% of cases 1. It usually resolves within seven days, though malaise and lassitude may persist for weeks 1. True myositis (distinct from myalgia) is uncommon and typically develops after subsidence of acute respiratory symptoms, affecting the gastrocnemius and soleus muscles with pain, tenderness, and elevated creatine phosphokinase 1.