What to give to a patient with influenza (flu)?

Treatment for Influenza Positive Patients

For patients with confirmed influenza, antiviral treatment with oseltamivir 75 mg twice daily for 5 days should be initiated as soon as possible, ideally within 48 hours of symptom onset, with greatest benefit seen when started within 24 hours. 1, 2, 3

Antiviral Therapy Algorithm

First-Line Treatment:

• Oseltamivir (Tamiflu):
  • Adults and children >24 kg: 75 mg twice daily for 5 days
  • Children 15-23 kg: 45 mg twice daily for 5 days
  • Children ≤15 kg: 30 mg twice daily for 5 days
  • Dose reduction: 75 mg once daily if creatinine clearance <30 ml/min 1

Key Timing Considerations:

• Treatment should begin within 48 hours of symptom onset
• Earlier treatment significantly improves outcomes:
  • Starting within 12 hours reduces illness duration by 74.6 hours (3.1 days)
  • Starting within 24 hours reduces illness duration by 53.9 hours (2.2 days) 3, 4

Patient Selection Criteria:

• Acute influenza-like illness
• Fever (>38°C in adults, >38.5°C in children)
• Symptomatic for ≤48 hours 1

Special Populations:

• Immunocompromised or elderly patients may benefit from treatment even without documented fever
• Hospitalized or severely ill patients may benefit from treatment started >48 hours after symptom onset 1

Antibiotic Management

Uncomplicated Influenza (without pneumonia):

• Previously well adults: No antibiotics routinely required
• Consider antibiotics for:
  • Worsening symptoms (recrudescent fever or increasing dyspnea)
  • High-risk patients with lower respiratory features
  • Patients with COPD or other severe pre-existing illnesses 1

Preferred Antibiotic Choices (if indicated):

• First-line: Co-amoxiclav or tetracycline (e.g., doxycycline)
• Alternative (for penicillin intolerance): Macrolide (clarithromycin or erythromycin) or respiratory fluoroquinolone 1, 5

Influenza with Pneumonia:

• Non-severe pneumonia: Oral co-amoxiclav or tetracycline
• Severe pneumonia: IV combination therapy with broad-spectrum β-lactamase stable antibiotic (co-amoxiclav or cephalosporin) plus macrolide 1

Supportive Care

• Fever management: Acetaminophen or ibuprofen for temperatures >38.5°C 5
• Hydration: Maintain adequate fluid intake 5
• Oxygen therapy: For hypoxic patients to maintain SaO2 ≥92% 5
• Nausea management: Take oseltamivir with food to reduce gastrointestinal side effects (affects ~10% of patients) 2, 3

Monitoring and Follow-up

• Monitor for worsening symptoms, particularly:
  • Increasing shortness of breath
  • Recrudescent fever
  • Development of pneumonia 1
• Consider hospital referral for patients with:
  • CRB-65 score of 1-2
  • Bilateral chest signs of pneumonia
  • Severe symptoms (respiratory rate >24/min, heart rate >100/min, SBP <90 mmHg, O2 saturation <90%) 1

Common Pitfalls to Avoid

1. Delayed treatment: Efficacy of antivirals decreases significantly after 48 hours of symptom onset
2. Overuse of antibiotics: Not routinely needed for uncomplicated influenza in previously well patients
3. Failure to recognize complications: Monitor for pneumonia and bacterial superinfection
4. Inappropriate zanamivir use: Avoid in patients with underlying respiratory disorders due to risk of bronchospasm 6
5. Missing high-risk patients: Elderly, immunocompromised, and those with chronic conditions require closer monitoring and lower threshold for antibiotic therapy

Remember that while antiviral treatment reduces illness duration by approximately 24 hours and may reduce complications, it has not been definitively shown to reduce overall mortality 1, 2.