What is the recommended treatment for influenza?

Influenza Treatment

Immediate Treatment Recommendation

Start oseltamivir 75 mg orally twice daily for 5 days as soon as possible for any patient with confirmed or suspected influenza who requires hospitalization, has severe/progressive illness, or is at high risk for complications, regardless of time since symptom onset. 1, 2

Who Requires Antiviral Treatment

Mandatory Treatment Groups

• Any hospitalized patient with confirmed or suspected influenza 3, 1
• Patients with severe, complicated, or progressive illness regardless of vaccination status or time since symptom onset 3, 1
• High-risk patients including:
  • Children younger than 2 years 3
  • Adults 65 years and older 3, 1
  • Pregnant and postpartum women (within 2 weeks after delivery) 3, 1
  • Immunocompromised patients 3, 1
  • Patients with chronic conditions (pulmonary, cardiovascular, renal, hepatic, metabolic, neurologic disorders) 3, 1

Consider Treatment For

• Otherwise healthy outpatients with uncomplicated influenza if treatment can be initiated within 48 hours of symptom onset 3
• Healthy children whose siblings are younger than 6 months or have high-risk conditions 3

Specific Medication Recommendations

First-Line Treatment: Oseltamivir

• Adults and adolescents ≥13 years: 75 mg orally twice daily for 5 days 1, 2
• Children 2 weeks to 12 years: Weight-based dosing (3 mg/kg twice daily for infants <1 year; 30-75 mg twice daily based on weight for children ≥1 year) 3, 2
• FDA-approved for children as young as 2 weeks 3, 2
• May be taken with or without food, though tolerability is enhanced with food 2

Alternative Agents

• Zanamivir: 10 mg (two inhalations) twice daily for 5 days for patients ≥7 years 1, 4
• Peramivir: Available as alternative per IDSA recommendations 1
• Baloxavir: Conditionally recommended for non-severe influenza in high-risk patients 5

Critical Timing Considerations

The 48-Hour Window

• Greatest benefit occurs when treatment starts within 48 hours of symptom onset 3
• Even greater benefit when started within 24 hours 6
• Treatment within 48 hours reduces mortality in hospitalized adults (adjusted OR 0.37) 3

Treatment Beyond 48 Hours

• Do not withhold treatment in severely ill or hospitalized patients even if >48 hours have passed since symptom onset 3, 1
• Treatment initiated within 5 days of symptom onset still reduces mortality in hospitalized patients (adjusted OR 0.50) 3
• Treatment after 48 hours provides some benefit in moderate-to-severe or progressive disease 3
• Treatment initiated >5 days after symptom onset was not associated with mortality reduction 3

Do Not Delay for Testing

• Start treatment immediately based on clinical suspicion—do not wait for laboratory confirmation 3
• Clinical judgment based on disease severity, underlying conditions, and local influenza activity guides decisions 3

Expected Treatment Benefits

Symptom Duration

• Reduces illness duration by approximately 17.6 hours in children with laboratory-confirmed influenza 3
• Reduces illness duration by up to 1.5 days in otherwise healthy adults 7
• Reduces illness duration by 2.5 days in high-risk patients 8

Complications

• Reduces risk of otitis media by 34% in children 3
• Reduces risk of pneumonia and other secondary complications 7
• Reduces antibiotic use 7

Viral Shedding

• Significantly reduces viral shedding on days 2,4, and 7 of treatment 9

Managing Bacterial Coinfection

Add empiric antibacterial therapy when bacterial coinfection is suspected, particularly in patients with:

• Initial severe disease 1
• Clinical deterioration after initial improvement 1
• Failure to improve after 3-5 days of antiviral treatment 1

Antibiotic Selection

• Preferred oral agents: Co-amoxiclav or tetracycline 3
• For severe pneumonia: Intravenous co-amoxiclav or cephalosporin (cefuroxime/cefotaxime) plus macrolide (clarithromycin/erythromycin) 3
• Target likely pathogens: Streptococcus pneumoniae, Staphylococcus aureus (including MRSA), Streptococcus pyogenes 3

Common Adverse Effects

• Vomiting is the most common side effect, occurring in approximately 15% of treated children versus 9% receiving placebo 3
• Nausea occurs but is reduced when oseltamivir is taken with food 3, 7
• No established link between oseltamivir and neuropsychiatric events despite earlier concerns from Japan 3

Critical Pitfalls to Avoid

What NOT to Do

• Do not use corticosteroids as adjunctive therapy for seasonal influenza 1
• Do not use amantadine or rimantadine due to high resistance rates among circulating influenza A viruses 1
• Do not use double-dose oseltamivir—no benefit over standard dosing 3
• Do not routinely prescribe antibiotics for uncomplicated influenza without evidence of bacterial coinfection 3

Special Considerations

• Adjust dosing in renal impairment—oseltamivir is not recommended for end-stage renal disease patients not on dialysis 2
• For patients using inhaled bronchodilators: Administer bronchodilator before zanamivir 4
• Resistance emergence is rare (<1% overall, 3.9% in H1N1pdm09) 9