What are the best management strategies for a patient experiencing leg pain due to influenza (flu)?

Management of Leg Pain from Influenza

Leg pain (myalgia) from influenza should be treated with paracetamol (acetaminophen) or ibuprofen for symptomatic relief, along with rest and adequate hydration, while monitoring for rare but serious complications like myositis. 1

Symptomatic Treatment

The primary approach to influenza-related leg pain is supportive care:

• Paracetamol or ibuprofen are the first-line antipyretics and analgesics for treating myalgias, fever, and headache associated with influenza 1, 2
• Rest is recommended during the acute illness phase 1, 2
• Adequate fluid intake should be maintained throughout the illness 1, 2
• Avoid smoking during the illness 1

Important caveat: Aspirin is absolutely contraindicated in children under 16 years due to the risk of Reye's syndrome 2, 3

When to Suspect Myositis (A Rare Complication)

While most leg pain from influenza is simple myalgia that resolves with symptomatic treatment, you must watch for myositis, which predominantly affects school-aged children and involves the calf muscles 1:

• Myositis typically presents with severe leg pain and muscle tenderness
• Rhabdomyolysis and renal failure are rare but possible complications 1
• If severe, progressive leg pain develops or the patient cannot bear weight, consider checking creatine kinase levels and monitoring renal function

Red Flags Requiring Re-evaluation

Patients should be instructed to return immediately if they develop any of the following warning signs 2, 4:

• Shortness of breath at rest or painful/difficult breathing
• Recrudescent fever (fever returning after initial improvement)
• Increasing dyspnea or worsening respiratory symptoms
• Altered mental status or drowsiness
• Inability to maintain oral intake
• Coughing up bloody sputum

These symptoms may indicate bacterial superinfection (particularly pneumonia) or other serious complications requiring antibiotics or hospitalization 1, 2.

Antiviral Considerations

Antivirals are not indicated for uncomplicated influenza with only myalgias unless specific criteria are met 1, 2:

• Antivirals should only be considered if the patient has all three of: acute influenza-like illness, fever >38°C, and has been symptomatic for ≤48 hours 1, 2
• The standard regimen is oseltamivir 75 mg every 12 hours for 5 days 1, 5
• Exception: High-risk patients (elderly ≥65 years, immunocompromised, pregnant women, those with chronic cardiac/respiratory disease) may benefit from oseltamivir even beyond 48 hours, particularly if severely ill or hospitalized 2, 4, 6

Antibiotics Are Not Indicated

Do not prescribe antibiotics for uncomplicated influenza with myalgias alone 1, 2:

• Previously healthy adults with influenza and myalgias do not require antibiotics unless they develop worsening symptoms suggesting bacterial superinfection 1
• Antibiotics should only be considered if the patient develops recrudescent fever, increasing dyspnea, or signs of pneumonia 1, 2

Monitoring and Follow-Up

Most patients with uncomplicated influenza and leg pain can be managed at home without face-to-face consultation 1:

• Provide clear instructions on self-care and when to seek further help 1
• Symptoms typically improve within 3-5 days, with complete resolution in 1-2 weeks 6, 7
• If symptoms persist beyond 7-10 days or worsen after initial improvement, re-evaluation is warranted 1, 2