Management of Influenza in a 17-Year-Old Without Underlying Medical Conditions
For an otherwise healthy 17-year-old with influenza, treatment with oseltamivir 75 mg orally twice daily for 5 days should be initiated as soon as possible, ideally within 48 hours of symptom onset, to reduce illness duration and symptom severity. 1
Treatment Decision Algorithm
Immediate treatment is recommended if:
- The patient presents within 48 hours of symptom onset 1
- Symptom reduction is desired 1
- The patient lives with high-risk household contacts (infants <6 months, immunocompromised individuals, or those with chronic medical conditions) 2
Treatment may still be considered if:
- The patient presents beyond 48 hours but has moderate-to-severe or progressive symptoms 3, 1
- Clinical judgment suggests significant benefit despite delayed presentation 3
Specific Dosing Instructions
Standard regimen for adolescents ≥13 years:
- Oseltamivir 75 mg orally twice daily for 5 days 1
- Can be taken with or without food, though administration with meals improves gastrointestinal tolerability 1
- No weight-based adjustment needed if patient weighs >40 kg 1
Expected Clinical Benefits
When initiated within 48 hours of symptom onset, oseltamivir provides:
- Reduction in illness duration by 17.6-29.9 hours (approximately 1-1.5 days) 3, 1, 4
- Decreased severity of symptoms by up to 38% 4
- 50% reduction in risk of pneumonia 3, 1
- Faster return to normal activities 4
- Reduced need for antibiotics 4
Alternative Antiviral Options
If oseltamivir is contraindicated or unavailable:
- Zanamivir (inhaled): 10 mg (two 5-mg inhalations) twice daily for 5 days, approved for ages ≥7 years 1
- Baloxavir (oral): Single dose of 40 mg (for 40-80 kg) or 80 mg (for ≥80 kg), approved for ages ≥12 years 1
- Peramivir (IV): Single 600 mg IV infusion over 15-30 minutes for ages 13-17 years 1, 5
Diagnostic Considerations
Do not delay treatment while awaiting laboratory confirmation 1, 2
- Clinical diagnosis based on acute onset of fever with cough or sore throat during influenza season is sufficient 3
- Rapid antigen tests have poor sensitivity; negative results should not exclude treatment 2
- RT-PCR is the gold standard but results take time—initiate empiric treatment in the interim 6
Common Adverse Effects to Anticipate
Gastrointestinal symptoms are most common:
- Nausea occurs in approximately 3.66% more patients than placebo (number needed to harm = 28) 6
- Vomiting occurs in approximately 15% of treated adolescents versus 9% on placebo 3, 2
- These effects are mild, transient, and rarely lead to discontinuation 3, 2
- Taking oseltamivir with food reduces gastrointestinal side effects 4
Neuropsychiatric concerns:
- Despite historical reports, controlled trials have failed to establish a link between oseltamivir and neurologic or psychiatric events 3, 2
- Abnormal behavior can occur with influenza itself, independent of antiviral treatment 3
Critical Pitfalls to Avoid
Do not withhold treatment while waiting for laboratory confirmation in patients presenting within 48 hours of symptom onset 1, 2
Do not automatically dismiss treatment if >48 hours have passed since symptom onset—if the patient has moderate-to-severe illness or high-risk features, treatment still provides benefit 3, 1
Do not reflexively add antibiotics unless there is clinical evidence of bacterial superinfection (new consolidation on imaging, purulent sputum, clinical deterioration despite oseltamivir, or elevated inflammatory markers) 6
Do not assume vaccination status eliminates the need for treatment—even vaccinated individuals can benefit from antiviral therapy when infected 2
Supportive Care Measures
In addition to antiviral therapy:
- Adequate hydration and rest 3
- Antipyretics for fever and myalgias (avoid aspirin in patients <19 years due to Reye's syndrome risk) 3
- Monitor for warning signs requiring urgent evaluation: difficulty breathing, persistent high fever beyond 3-4 days, altered mental status, or clinical deterioration 2