What is the recommended treatment for influenza (flu)?

Treatment of Influenza (Flu)

The recommended treatment for influenza includes antiviral therapy with oseltamivir 75 mg twice daily for 5 days for patients with acute influenza-like illness who have been symptomatic for 48 hours or less, with supportive care measures for all patients. 1, 2

Antiviral Treatment Recommendations

Who Should Receive Antiviral Treatment:

• Antiviral treatment should be initiated as soon as possible for: 3, 1

  • Hospitalized patients with confirmed or suspected influenza
  • Patients with severe or progressive illness
  • High-risk patients (children <2 years, adults ≥65 years, pregnant women, immunocompromised individuals, and those with chronic medical conditions)

• Consider antiviral treatment for previously healthy outpatients with suspected or confirmed influenza if they can be treated within 48 hours of symptom onset 3, 1

• Patients who cannot mount an adequate febrile response (immunocompromised or elderly) may still benefit from antiviral treatment despite lack of documented fever 3

First-Line Antiviral Options:

• Oseltamivir (oral): 75 mg twice daily for 5 days for adults; weight-based dosing for children 1, 2

  • Most accessible and widely used option
  • Reduce dose to 75 mg once daily if creatinine clearance is <30 mL/min 2

• Zanamivir (inhaled): 10 mg (2 inhalations) twice daily for 5 days 4

  • Alternative for patients who cannot tolerate oseltamivir
  • Not recommended for patients with underlying respiratory conditions 5, 4

Timing of Antiviral Treatment:

• Greatest benefit when started within 24-48 hours of symptom onset 1, 6
• Can reduce duration of illness by approximately 1-1.5 days 6, 7
• May still be beneficial in hospitalized patients with severe illness when started >48 hours after symptom onset 3

Management of Complications

Uncomplicated Influenza:

• Previously well adults with acute bronchitis complicating influenza do not routinely require antibiotics 3, 8
• Focus on symptomatic management with antipyretics and adequate hydration 3
• Note: Aspirin should not be used in children due to risk of Reye syndrome 3

Non-Severe Influenza-Related Pneumonia:

• Consider antibiotics for patients who develop worsening symptoms (recrudescent fever or increasing dyspnea) 3
• Preferred oral antibiotics include co-amoxiclav or a tetracycline 3, 8
• Alternative options include macrolides (clarithromycin/erythromycin) or respiratory fluoroquinolones 3

Severe Influenza-Related Pneumonia:

• Immediate treatment with parenteral antibiotics is essential 3, 8
• Preferred regimen: IV combination of broad-spectrum beta-lactamase stable antibiotic (co-amoxiclav or cephalosporin) plus a macrolide 3, 1
• Duration of antibiotic therapy: 7 days for uncomplicated pneumonia; 10-14 days for severe cases 3

Special Considerations

Children:

• Oseltamivir is approved for treatment in children ≥2 weeks of age 2
• Weight-based dosing is essential for children 5, 2
• Liquid formulation (6 mg/mL) is available for children who cannot swallow capsules 2

High-Risk Populations:

• More aggressive approach to treatment is warranted for:
  • Pregnant women 3, 5
  • Immunocompromised patients (may benefit from longer treatment duration) 1, 5
  • Adults ≥65 years and children <2 years 3, 5
  • Those with chronic medical conditions 3, 5

Common Pitfalls and Caveats

• Do not delay antiviral treatment while awaiting diagnostic test results - empiric treatment is often necessary for high-risk patients 3, 1

• Avoid unnecessary antibiotic use in uncomplicated influenza without evidence of bacterial infection 8

• Be vigilant for secondary bacterial pneumonia, which typically develops 4-5 days after initial influenza symptoms 8

• Recognize that rapid influenza diagnostic tests have limited sensitivity and should not be used to rule out influenza, especially during peak season 1

• Amantadine and rimantadine should not be used due to high levels of resistance 3