What is the recommended management for a patient with influenza?

Management of Influenza

Antiviral Treatment

Start oseltamivir 75 mg orally twice daily for 5 days in patients presenting within 48 hours of symptom onset who have fever >38°C and acute influenza-like illness. 1, 2

Timing and Eligibility Criteria

• Initiate treatment as early as possible within the 48-hour window—treatment started within 12 hours reduces illness duration by an additional 74.6 hours compared to treatment at 48 hours, and within 24 hours by an additional 53.9 hours 3
• All three criteria must be present for standard antiviral treatment: (1) acute influenza-like illness, (2) fever >38°C, and (3) symptom duration ≤2 days 4
• Immunocompromised or very elderly patients may receive antivirals despite lack of documented fever, as they may not mount adequate febrile responses 4, 1
• Severely ill hospitalized patients, particularly if immunocompromised, may benefit from oseltamivir even when started >48 hours after symptom onset, though evidence for this is limited 4, 1

Dosing Adjustments

• Reduce dose to 75 mg once daily if creatinine clearance <30 mL/min 4, 2
• Pediatric dosing is weight-based: 30 mg twice daily for ≤15 kg, 45 mg for 15.1-23 kg, 60 mg for 23.1-40 kg, and 75 mg for >40 kg 1, 2
• Take with food to reduce gastrointestinal side effects 2, 3

Expected Benefits

• Reduces illness duration by approximately 24 hours 1, 5
• Decreases severity of illness by up to 38% 5
• Reduces hospitalization rates and need for subsequent antibiotic use 1
• Significantly reduces viral shedding on days 2,4, and 7 of treatment 6

Antibiotic Management

Uncomplicated Influenza Without Pneumonia

Do not routinely prescribe antibiotics for previously healthy adults with acute bronchitis complicating influenza in the absence of pneumonia. 4, 7

• Consider antibiotics only if worsening symptoms develop (recrudescent fever or increasing dyspnea) 4
• High-risk patients should receive antibiotics if lower respiratory features are present 4
• Preferred oral antibiotics: co-amoxiclav or tetracycline 4
• Alternative options: macrolide (clarithromycin or erythromycin) or respiratory fluoroquinolone (levofloxacin or moxifloxacin) 4

Non-Severe Influenza-Related Pneumonia

• Treat with oral co-amoxiclav or tetracycline as first-line therapy 4, 7
• If oral therapy contraindicated, use IV co-amoxiclav or second/third-generation cephalosporin (cefuroxime or cefotaxime) 4
• Administer antibiotics within 4 hours of admission 4

Severe Influenza-Related Pneumonia

Immediately treat with IV combination therapy: broad-spectrum β-lactamase stable antibiotic (co-amoxiclav or cefuroxime/cefotaxime) plus a macrolide (clarithromycin or erythromycin). 4, 7

• Alternative regimen: respiratory fluoroquinolone with enhanced pneumococcal activity plus broad-spectrum β-lactamase stable antibiotic or macrolide 4
• Switch to oral antibiotics once clinical improvement occurs and temperature normal for 24 hours 4

Hospitalization and Discharge Criteria

Criteria for Continued Hospitalization

Patients with ≥2 of the following unstable clinical factors should remain hospitalized: 4

• Temperature >37.8°C
• Heart rate >100/min
• Respiratory rate >24/min
• Systolic blood pressure <90 mmHg
• Oxygen saturation <90%
• Inability to maintain oral intake 4
• Abnormal mental status 4

Follow-Up

• Arrange follow-up for all patients with significant complications or worsening of underlying disease with their general practitioner or hospital clinic 4, 7
• Provide discharge information about illness, medications, and follow-up arrangements 4, 7

Prophylaxis

• For post-exposure prophylaxis, use oseltamivir 75 mg once daily for 10 days following close contact with infected individual, initiated within 48 hours of exposure 2, 5
• For seasonal prophylaxis during community outbreak, continue oseltamivir 75 mg once daily for up to 6 weeks 2, 5
• Immunocompromised patients may continue prophylaxis for up to 12 weeks 2

Common Pitfalls

• Avoid unnecessary antibiotics in uncomplicated influenza—bacterial co-infection typically develops 4-5 days after initial symptoms, not at presentation 7
• Nausea occurs in ~10% of patients on oseltamivir—this is transient (1-2 days) and reduced when taken with food 3, 5
• Oseltamivir resistance is rare (<1%) and clinically insignificant due to reduced transmissibility of resistant strains 3, 6
• Be vigilant for Staphylococcus aureus pneumonia, which is more common during influenza outbreaks than typical community-acquired pneumonia 7