Precautions of Xofluza

1. Hypersensitivity

Cases of anaphylaxis, urticaria, angioedema, and erythema multiforme have been reported during the postmarketing experience of baloxavir marboxil. Appropriate treatment should be initiated if an anaphylactoid reaction occurs or is suspected. Baloxavir marboxil is contraindicated in patients with known hypersensitivity to baloxavir marboxil.

2. Increased Incidence of Treatment-Emergent Resistance in Patients Younger Than 5 Years

Baloxavir marboxil is not indicated for patients younger than 5 years of age because of the higher incidence of treatment-emergent resistance in this age group. In clinical trials, the incidence of viruses with treatment-emergent substitutions associated with reduced susceptibility to baloxavir marboxil (resistance) was higher in pediatric subjects younger than 5 years (40%, 38/96) than in pediatric subjects aged 5 to<12 years (16%, 19/117) or subjects ≥12 years (7%, 60/842). The potential for community transmission of resistant strains has not been determined.

3. Risk of Bacterial Infections

There is no evidence that baloxavir marboxil is effective for any illness caused by pathogens other than influenza virus. Serious bacterial infections may begin with influenza-like symptoms or may coexist with or occur as complications of influenza. Baloxavir marboxil has not been shown to prevent such complications. Prescribers should be alert to potential secondary bacterial infections and treat them as appropriate.

FDA，2025.05