When should Oseltamivir (Tamiflu) be started in children with influenza?

When to Start Tamiflu in Children with Influenza

Oseltamivir (Tamiflu) should be started as soon as possible after symptom onset in children with influenza, ideally within 48 hours, as earlier treatment provides better clinical outcomes. 1

Priority Treatment Recommendations

Treatment should be offered as early as possible for:

• Any hospitalized child clinically presumed to have influenza or with severe, complicated, or progressive illness attributable to influenza 1
• Children at high risk of influenza complications regardless of illness duration 1
• Children younger than 2 years, who are at increased risk of hospitalization and complications from influenza 1

Treatment should be considered for:

• Any otherwise healthy child with influenza whose siblings are either younger than 6 months or have underlying medical conditions that predispose them to complications 1
• Any healthy child with presumed influenza when a decrease in duration of clinical symptoms is warranted 1

Timing of Treatment

• Start treatment as soon as possible after symptom onset - do not delay while waiting for definitive influenza test results 1
• Treatment within 12 hours of symptom onset has shown to decrease the incidence of acute otitis media by 85% in children 1-3 years of age 2
• Treatment within 24 hours of symptom onset can shorten the median time to resolution of illness by 3.5 days in children with influenza A 2
• While optimal timing is within 48 hours, treatment after 48 hours of symptoms in children with moderate to severe or progressive disease has shown some benefit and should still be considered 1

Treatment Considerations by Age

• FDA has approved oseltamivir for children as young as 2 weeks 1
• The AAP supports the use of oseltamivir in both term and preterm infants from birth for treatment of influenza, as benefits likely outweigh risks 1
• For children under 1 year: Weight-based dosing should be used 1
• For children 1-12 years: 2 mg/kg twice daily for 5 days (with appropriate weight-based adjustments) 1, 3

Clinical Decision-Making Factors

• Base treatment decisions on:

  • Underlying conditions of the child 1
  • Disease severity 1
  • Time since symptom onset 1
  • Local influenza activity 1

• Do not rely on negative rapid antigen test results to rule out influenza due to suboptimal sensitivity; consider molecular assays which provide higher sensitivity 1

Efficacy and Safety Considerations

• Timely oseltamivir treatment can reduce the duration of fever and illness symptoms and the risks of complications, including hospitalization and death 1, 4
• Standard-dose therapy is recommended, as double-dose therapy has not shown additional benefit 1, 5
• The most common side effect is vomiting (15% of treated children vs. 9% receiving placebo) 1
• Taking oseltamivir with food may reduce gastrointestinal side effects 4
• Despite some conflicting evidence regarding efficacy 6, major guidelines consistently recommend early treatment for high-risk children and those with severe disease 1

Important Caveats

• Treatment efficacy has not been evaluated in randomized trials for hospitalized children or children with comorbid conditions 1
• Some studies show limited efficacy against influenza B compared to influenza A 2, 6
• The Cochrane review suggested no evidence demonstrating an effect on complications, hospitalizations, or death, describing overall performance as "modest" 1
• Despite these limitations, most experts support the use of oseltamivir to reduce complications and hospitalizations 1