The choice of antiviral therapy for individual benefit in patients with influenza

Treatment of influenza with a neuraminidase inhibitor (eg oseltamivir), has been associated with fewer complications, hospital admissions and deaths due to influenza in systematic reviews of observational studiesHsu, 2012Michiels, 2013. These studies included people at high risk of severe influenza or mortality due to influenza (eg patients in hospital, pregnant and postnatal patients). By contrast, systematic reviews of randomised controlled trials did not demonstrate such benefitsHanula, 2023.

Treatment of influenza with baloxavir (a cap-dependent endonuclease inhibitor) has been shown to have a similar time to clinical improvement as oseltamivir when started within 48 hours of symptom onsetCenter for Disease Control (CDC), 2022Gao, 2025Hayden, 2018Ison, 2020.

The choice of antiviral therapy can be guided by local epidemiology and the resistance profile of the strain of influenza. Epidemics can be caused by strains resistant to neuraminidase inhibitors (usually oseltamivir). Resistance to neuraminidase inhibitors and baloxavir has also emerged during therapyGao, 2025Kumari, 2023; use baloxavir with caution in patients with influenza and immune compromiseIson, 2020World Health Organization (WHO), 2024. For current surveillance data, see the Australian Influenza Surveillance Reports (AISR).

For patients with influenza who are pregnant or up to 2 weeks postpartum, observational data show treatment with a neuraminidase inhibitor is associated with a reduction in severe outcomes, without increased risk of adverse maternal, fetal or neonatal outcomesChow, 2021. At the time of writing, there are no data to support the use of baloxavir for patients who are pregnant or postpartumWorld Health Organization (WHO), 2024.

Patients who require ventilatory or haemodynamic support who can tolerate or absorb oral therapy should be treated with standard-dose oral oseltamivir. If they cannot tolerate and absorb oral therapy, consider intravenous peramivir. For further discussion, see Antiviral regimens for individual benefit in patients with severe influenza.

For an overview of antiviral drugs, see Practical information on using neuraminidase inhibitors and Practical information on using baloxavir.