What is the adult dose of Xofluza (Baloxavir marboxil)?

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Last updated: May 23, 2025View editorial policy

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From the Guidelines

The adult dose of Xofluza (baloxavir marboxil) for treating influenza is a single oral dose based on body weight: 40 mg for adults weighing 20 kg to less than 80 kg, or 80 mg for adults weighing 80 kg or more. This recommendation is based on the most recent and highest quality study available, which provides guidance on the use of antiviral medications for the treatment of influenza 1. The medication should be taken as soon as possible within 48 hours of symptom onset for maximum effectiveness. Some key points to consider when prescribing Xofluza include:

  • Xofluza works differently from older antiviral medications by inhibiting the cap-dependent endonuclease enzyme, preventing viral replication.
  • The medication can be taken with or without food, but it is recommended to avoid taking it with dairy products, calcium-fortified beverages, laxatives, antacids, or supplements containing iron, zinc, selenium, calcium, or magnesium, as these can reduce the medication's effectiveness.
  • Common side effects may include diarrhea, bronchitis, nausea, and headache, as reported in the study 1.
  • Xofluza is not recommended for pregnant women, nursing mothers, or children under 5 years of age without medical supervision, due to limited safety and efficacy data in these populations.

From the FDA Drug Label

2 DOSAGE AND ADMINISTRATION

2.1 Dosage and Administration Overview XOFLUZA is available in two dosage forms: XOFLUZA tablets (40 mg and 80 mg). ... 2. 2 Recommended Dosage Treatment of Acute Uncomplicated Influenza or Post-Exposure Prophylaxis in Adults, and Pediatric Patients (5 Years of Age and Older) XOFLUZA should be taken as a single dose as soon as possible and within 48 hours of influenza symptom onset for treatment of acute uncomplicated influenza or following contact with an individual who has influenza The recommended dosage of XOFLUZA in patients 5 years of age or older is a single weight-based dose displayed in Tables 1 and 2 Table 1 Recommended XOFLUZA Tablet Dosage in Adults and Pediatric Patients 5 Years of Age and Older Patient Body Weight (kg) | Recommended Single Oral Dose (Tablets) 20 kg to less than 80 kg | One 40 mg tablet At least 80 kg | One 80 mg tablet

The adult dose of Xofluza is a single weight-based dose:

  • For adults weighing 20 kg to less than 80 kg: one 40 mg tablet
  • For adults weighing at least 80 kg: one 80 mg tablet 2

From the Research

Xofluza Adult Dose

  • The recommended dose of Xofluza (baloxavir marboxil) for adults is a single oral dose, as stated in the study 3.
  • Xofluza is approved in the USA for the treatment of acute uncomplicated influenza in patients ≥ 12 years of age who have been symptomatic for ≤ 48 hours, according to the study 3.
  • The study 4 compared the efficacy and safety of neuraminidase inhibitors and the endonuclease inhibitor (baloxavir) for the treatment of seasonal influenza among healthy adults and children, but did not specify the dose.
  • Other studies 5, 6, 7 did not provide information on the adult dose of Xofluza.

Efficacy and Safety

  • Baloxavir has been shown to be efficacious in improving influenza symptoms in otherwise healthy adolescents and adults, as well as in those at high risk of influenza complications, with similar efficacy to oseltamivir 3.
  • The study 4 found that baloxavir was associated with the lowest risk of influenza-related complications and the lowest risk of total adverse events compared with placebo.
  • Baloxavir has activity against influenza A and B viruses, including strains resistant to neuraminidase inhibitors, and is well tolerated 3.

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.

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