What are the indications for treating influenza (influenza virus infection)?

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Last updated: February 27, 2025 • View editorial policy

From the Guidelines

Treatment for influenza should be started promptly in high-risk patients or those with severe symptoms, as early antiviral treatment can reduce the risk of complications from influenza, such as pneumonia, respiratory failure, and death 1. The indications for treating influenza include patients who are hospitalized, have severe, complicated, or progressive illness, or are at higher risk for influenza complications, such as:

  • Children aged <2 years
  • Adults aged ≥65 years
  • Persons with chronic pulmonary, cardiovascular, renal, hepatic, hematological, metabolic disorders, or neurologic and neurodevelopment conditions
  • Persons with immunosuppression, including that caused by medications or by HIV infection
  • Women who are pregnant or postpartum (within 2 weeks after delivery) Antiviral medications like oseltamivir (Tamiflu) 75mg twice daily for 5 days are most effective when begun within 48 hours of symptom onset, and can be used for treatment or chemoprophylaxis of influenza among infants aged <1 year when indicated 2. Alternative antivirals include zanamivir (Relenza), peramivir (Rapivab), or baloxavir (Xofluza) 1. Supportive care is essential, including rest, hydration, and fever control with acetaminophen or ibuprofen. Antiviral treatment should be started as soon as possible after illness onset, and should not be delayed while awaiting the results of diagnostic testing 3. Even without treatment, most healthy individuals will recover within 1-2 weeks, but antivirals can reduce transmission risk to others. If influenza is suspected, isolation is recommended until 24 hours after fever resolves. The duration of antiviral treatment can be considered for a longer period for patients with a documented or suspected immunocompromising condition or patients requiring hospitalization for severe lower respiratory tract disease 1.

From the FDA Drug Label

1 INDICATIONS AND USAGE

1.1 Treatment of Influenza Oseltamivir phosphate for oral suspension is indicated for the treatment of acute, uncomplicated illness due to influenza A and B infection in patients 2 weeks of age and older who have been symptomatic for no more than 48 hours.

1 INDICATIONS AND USAGE

1.1 Treatment of Influenza RELENZA (zanamivir) inhalation powder is indicated for treatment of uncomplicated acute illness due to influenza A and B virus in adults and pediatric patients aged 7 years and older who have been symptomatic for no more than 2 days.

The indications for treating influenza (influenza virus infection) are:

  • Treatment of acute, uncomplicated illness due to influenza A and B infection in patients: + 2 weeks of age and older (oseltamivir) who have been symptomatic for no more than 48 hours. + 7 years and older (zanamivir) who have been symptomatic for no more than 2 days. 4 5

From the Research

Indications for Treating Influenza

The indications for treating influenza include:

  • Patients at high-risk of influenza-related complications, such as young children, the elderly, pregnant and post-partum women, patients with co-morbidities, and the immunocompromised 6
  • Hospitalised patients with suspected or proven influenza 6
  • Patients with severe or progressive disease 6
  • Previously healthy patients when therapy can be initiated within 48 hours of symptom onset 6, 7
  • Patients who present late, but are at high risk of influenza-related complications 6

Treatment Options

Treatment options for influenza include:

  • Neuraminidase inhibitors (NAIs), such as oseltamivir and zanamivir, which are the treatment of choice for influenza 6, 8
  • Oseltamivir, which can be administered via nasogastric tube in intubated patients 6
  • Zanamivir, which can be administered via inhalation or intravenously in patients with oseltamivir-resistant virus 6
  • Baloxavir, an endonuclease inhibitor, which can be used in patients with influenza infection 8

Timing of Treatment

The timing of treatment is crucial, with early initiation, preferably within 48 hours of symptom onset, being essential to produce favourable outcomes in patients with influenza infection 6, 7, 8

  • Treatment should be initiated as soon as possible in patients at high-risk of influenza-related complications 6
  • In previously healthy patients, the therapeutic efficacy of oseltamivir is time-dependent, with maximal benefit observed when therapy is initiated within 48 hours of symptom onset 6
  • However, several observational studies suggest therapeutic benefit beyond 48 hours, in hospitalised patients, severe disease, and patients at high risk of complications, including pregnant women 6, 9

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.