Treatment of Influenza B
Oseltamivir (Tamiflu) is the recommended first-line treatment for influenza B, with a standard dosage of 75 mg twice daily for 5 days in adults. 1, 2, 3
Recommended Antiviral Medications
- Oral oseltamivir remains the antiviral drug of choice for the management of influenza B infections, available in capsule and oral suspension formulations (6 mg/mL concentration) 4, 1
- Inhaled zanamivir is an acceptable alternative for patients who do not have chronic respiratory disease but is more difficult to administer 4, 1
- Intravenous peramivir is approved for treatment of acute uncomplicated influenza in children 2 years and older who have been symptomatic for no more than 2 days 4, 1
Dosing Guidelines
Adults and Adolescents (≥13 years)
Children (based on weight)
Infants
- 9-11 months: 3.5 mg/kg per dose twice daily for 5 days 4, 1
- 0-8 months: 3 mg/kg per dose twice daily for 5 days 4, 1
- Preterm infants:
Timing of Treatment
- Treatment should be initiated as soon as possible after symptom onset, ideally within 48 hours, as this provides the greatest benefit 1, 2
- Early treatment is associated with shorter duration of symptoms (reduced by approximately 24-36 hours) and decreased risk of complications 1, 5
- Do not delay treatment while waiting for confirmatory test results in high-risk patients or those with severe illness 1, 2
Special Populations Requiring Treatment
- All hospitalized patients with suspected or confirmed influenza B 1, 2
- Patients with severe, complicated, or progressive illness 1, 2
- High-risk patients including:
- Children <2 years of age 4
- Adults ≥65 years 4
- Individuals with chronic medical conditions (pulmonary, cardiovascular, renal, hepatic, hematologic, metabolic, or neurologic disorders) 4
- Immunocompromised individuals 4
- Pregnant women and women up to 2 weeks postpartum 4
- Children on long-term aspirin therapy 4
- American Indian/Alaska Native individuals 4
- Morbidly obese individuals (BMI ≥40) 4
- Residents of nursing homes and chronic care facilities 4
Efficacy Considerations for Influenza B
- While neuraminidase inhibitors are effective against both influenza A and B, more clinical data are available for influenza A than B 4, 2
- Some observational studies suggest oseltamivir might be less effective for influenza B than influenza A, with Japanese children with influenza A resolving fever and stopping viral shedding more quickly than children with influenza B when treated with oseltamivir 4, 2
- Despite this, oseltamivir has demonstrated significant antiviral activity against influenza B in experimental human infections 6
Common Side Effects and Management
- Vomiting is the most common side effect of oseltamivir, occurring in approximately 5% of treated patients 1, 2
- Taking oseltamivir with food may enhance tolerability and reduce gastrointestinal side effects 3, 5
- Despite reports of neuropsychiatric adverse effects, reviews of controlled clinical trial data have failed to establish a link between oseltamivir and neurologic or psychiatric events 1
Important Clinical Considerations
- Antiviral medications are not a substitute for vaccination, which remains the cornerstone for influenza prevention 2, 3
- For severely ill patients or immunocompromised patients, treatment is recommended regardless of time since symptom onset 1, 2
- No reduction in dosage is recommended based on age alone, but dosage adjustments are necessary for patients with renal impairment 4, 3
- Continuous monitoring of resistance patterns is important, though most recent influenza B strains remain susceptible to oseltamivir, zanamivir, and peramivir 1