What treatment can be given to someone who has tested positive for influenza (flu)?

Treatment for Influenza-Positive Patients

Start oseltamivir 75 mg orally twice daily for 5 days if the patient presents within 48 hours of symptom onset, has fever >38°C, and has acute influenza-like illness. 1

Antiviral Therapy: Oseltamivir as First-Line

Oseltamivir is the primary antiviral treatment for confirmed influenza. The standard adult dose is 75 mg orally every 12 hours for 5 days. 2, 1 This regimen should be initiated as soon as possible, ideally within 48 hours of symptom onset, when benefit is greatest. 1, 3

Key Eligibility Criteria for Antiviral Treatment:

• Acute influenza-like illness with fever >38°C 2, 1
• Symptomatic for ≤48 hours 2, 1
• Positive influenza test (as in your case) 3

Important Exceptions to the 48-Hour Rule:

• Hospitalized patients who are severely ill should receive oseltamivir even if >48 hours from symptom onset, particularly if immunocompromised 2, 1
• Patients unable to mount adequate febrile response (immunocompromised, very elderly) may still benefit from treatment despite lack of documented fever 2

Dose Adjustments:

• Reduce dose to 75 mg once daily if creatinine clearance <30 mL/min 2, 4
• For critically ill adults, some experts recommend doubling the dose to 150 mg twice daily 2

Alternative Antiviral Options:

• Zanamivir (inhaled) is an alternative neuraminidase inhibitor for patients unable to take oseltamivir 1
• Peramivir (IV) may be considered for severely ill patients who cannot absorb oral medications or have progressed despite oral therapy 2, 5

Antibiotic Therapy: Only When Indicated

Previously healthy adults with influenza do NOT routinely require antibiotics. 2, 1 Influenza is a viral illness, and antibiotics have no effect on the virus itself. 6

When to Add Antibiotics:

Consider antibiotics only if:

• Worsening symptoms develop (recrudescent fever or increasing dyspnea) suggesting secondary bacterial infection 2, 1
• Patient is at high risk of complications AND has lower respiratory tract features 2, 1
• Confirmed or suspected bacterial pneumonia on imaging or clinical grounds 1

Antibiotic Selection by Severity:

For non-severe influenza-related pneumonia (oral therapy):

• First-line: Co-amoxiclav or tetracycline 2, 1
• Alternative (penicillin allergy): Macrolide (clarithromycin or erythromycin) or fluoroquinolone (levofloxacin, moxifloxacin) 2

For severe influenza-related pneumonia (parenteral therapy):

• Immediate IV combination therapy required: Co-amoxiclav or 2nd/3rd generation cephalosporin (cefuroxime or cefotaxime) PLUS macrolide (clarithromycin or erythromycin) 2, 1
• Antibiotics must be administered within 4 hours of admission 2, 1

Antibiotic Duration:

• Switch from IV to oral when clinically improved, temperature normal for 24 hours, and oral route feasible 2, 1
• 7 days for non-severe, uncomplicated pneumonia 2, 1
• 10 days for severe, microbiologically undefined pneumonia 2, 1
• 14-21 days if S. aureus or Gram-negative pneumonia confirmed/suspected 2, 1

Supportive Care Measures

All patients should receive:

• Antipyretics for fever control (avoid aspirin in children due to Reye's syndrome risk) 1
• Adequate hydration 1
• Rest and symptom monitoring 3

Common Pitfalls to Avoid

Do not delay antiviral treatment waiting for laboratory confirmation if clinical suspicion is high and patient presents within 48 hours. 3, 7 The decision to treat should be made clinically.

Do not prescribe antibiotics reflexively. The vast majority of influenza cases do not require antibiotics unless secondary bacterial infection develops. 2, 1, 6

Do not assume oseltamivir is ineffective after 48 hours in high-risk or hospitalized patients. These patients may still benefit from treatment even with delayed presentation. 2, 1

Special Populations

Immunocompromised patients (transplant recipients, those on immunosuppression) may require longer treatment courses and consideration of IV antivirals if severely ill. 2 Consider reducing immunosuppression in patients with significant disease. 2

Pregnant women are at high risk of complications and should be treated with oseltamivir, preferably within 48 hours of symptom onset. 7