Table 3.

Antiviral medications for treatment of influenza

	Dosing	Mechanism of action	Considerations
Oseltamivir (oral suspension or capsule)	Duration of treatment, 5 days; age <1 year, 3 mg/kg twice per day; age ≥1 year and weight ≤15 kg, 30 mg twice per day; weight 16 kg to 23 kg, 45 mg twice per day; weight 24 kg to 40 kg, 60 mg twice per day; weight >40 kg, 75 mg twice per day; and adults, 75 mg twice per day	Inhibits influenza viral neuraminidase; blocks release of progeny virions from infected respiratory epithelial cells	Widely available in generic formulation; can be administered enterically via orogastric or nasogastric tubes; recommended for pregnant people; recommended for patients who are hospitalised; no completed fully enrolled placebo-controlled trials; increased risk of nausea or vomiting; dosage should be adjusted for patients with reduced creatinine clearance or receiving dialysis; can be given for prophylaxis after exposure once per day for 7 days; and might have lower effectiveness against influenza B virus infections
Zanamivir* (inhaled powder)	Duration of treatment, 5 days; age ≥7 years, 10 mg (two inhalations) twice per day	Inhibits influenza viral neuraminidase; blocks release of progeny virions from infected respiratory epithelial cells	Less available than oseltamivir; contraindicated in people with chronic airway disease because of increased risk of bronchospasm; insufficient data for patients who are hospitalised; intravenous zanamivir might be available in some countries; and laninamivir (single inhalation) is a related long-acting inhaled neuraminidase inhibitor approved for treatment of influenza in Japan
Peramivir (intravenous)	Duration of treatment, single dose via intravenous infusion; age 6 months to 12 years, 12 mg/kg up to 600 mg; and age ≥13 years, 600 mg	Inhibits influenza viral neuraminidase; blocks release of progeny virions from infected respiratory epithelial cells	Less available than oseltamivir; insufficient data for patients who are hospitalised
Baloxavir (oral suspension or capsule)	Duration of treatment, single dose; age ≥5 years and weight <20 kg, 2mg/kg; weight 20 kg to <80 kg, 40 mg; and weight ≥80 kg, 80 mg	Inhibits cap-dependent endonuclease within the polymerase acidic-protein subunit of viral polymerase; blocks viral replication in infected cells	Similar clinical benefit to 5 days of oseltamivir; significantly reduces influenza viral RNA concentrations in the upper respiratory tract after single dose; greater efficacy against influenza B virus infection than oseltamivir; reduces some complications in patients at high risk; not recommended for pregnant people; not recommended as monotherapy in people who are severely immunocompromised; single dose can be given as prophylaxis after exposure

Check national recommendations for the availability of antivirals and differences in age approvals and duration of treatment, including in patients who are immunocompromised. Greatest clinical benefit is when treatment is started within 2 days of illness onset in outpatients with uncomplicated influenza. The information here is partially obtained from the Centers for Disease Control and Prevention.⁸⁰

^*Intravenous zanamivir might be available in some countries. For example, intravenous zanamivir received marketing authorisation in the EU in 2019 for the treatment of patients aged 6 months or older with complications and potentially life-threatening influenza caused by influenza virus with known or suspected resistance to antivirals other than zanamivir, and, or when other antivirals, including inhaled zanamivir, are not suitable. Consult national recommendations for availability and indicated use.