Prescription medication · Endonuclease Inhibitor (Antiviral)
baloxavir marboxil
Also sold as Xofluza. Xofluza is used to treat the flu in people 5 years and older.
Data updated 2026-05-15
- 2,164
- FDA reportsRarely reported
- 2
- InteractionsFew interactions
- $157.18
- Brand price (NADAC)
What the data shows
baloxavir marboxil (Xofluza) is a prescription Endonuclease Inhibitor (Antiviral), among the least-reported drugs the FDA tracks (2,164 FDA reports), with 2 documented drug interactions.
Reporting volume reflects how widely a drug is used and studied, not how dangerous it is, a FAERS report documents a temporal association, never proof of cause.
baloxavir marboxil (Xofluza) is a prescription Endonuclease Inhibitor (Antiviral). Xofluza is used to treat the flu in people 5 years and older.
Xofluza is an antiviral medicine that can treat the flu. It can also prevent the flu if you have been around someone who is sick.
Verify with FDA → · CMS NADAC pricing →
Drug Pricing (NADAC)
Brand Price
$157.18/unit
Generic Available
No
GENENTECH INC
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
Xofluza is used to treat the flu in people 5 years and older.
Common side effects
Diarrhea, Bronchitis, Nausea
Key warnings
Xofluza can cause allergic reactions like anaphylaxis.
The sections below are summarized in plain English from baloxavir marboxil's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.
How It Works
Xofluza stops the flu virus from making more copies of itself in your body. It does this by blocking a protein the virus needs to grow. This helps you get better faster or prevents you from getting sick.
How to Take It
Take Xofluza as a single dose as soon as possible, but within 48 hours of when your flu symptoms started or after you were exposed to the flu. You can take Xofluza with or without food. The dose you need depends on your weight. If you weigh less than 80 kg (176 lbs), you will take one 40 mg tablet. If you weigh 80 kg (176 lbs) or more, you will take one 80 mg tablet.
This is a plain-language summary of baloxavir marboxil's FDA labeling, not individualized dosing advice. Ask a pharmacist or prescriber before changing how you take this medication.
Pregnancy & Breastfeeding
Tell your doctor if you are pregnant or plan to become pregnant. The benefits of taking Xofluza should be weighed against any potential risks to the baby. It is not known if Xofluza passes into breast milk. Talk to your doctor about the best way to feed your baby if you take Xofluza.
This is a plain-language summary of baloxavir marboxil's FDA labeling, not individualized advice. Ask a pharmacist or prescriber about pregnancy or breastfeeding on this medication.
Missed Dose
Xofluza is taken as a single dose, so you don't have to worry about missing a dose.
This is a plain-language summary of baloxavir marboxil's FDA labeling, not individualized advice. Ask a pharmacist or prescriber what to do about your specific missed dose.
Storage
Store Xofluza tablets in their original blister package at room temperature, between 68°F and 77°F.
Side Effects (from patient reports)
Based on 2,164 FDA adverse event reports.
Most-reported reactions
Adverse reactions in FAERS for baloxavir marboxil, by number of reports
- Diarrhoea
Diarrhoea
129 reports
- Vomiting
Vomiting
120 reports
- Pneumonia
Pneumonia
111 reports
- Nausea
Nausea
70 reports
- Rash
Rash
61 reports
- Headache
Headache
58 reports
- Influenza
Influenza
57 reports
- Colitis Ischaemic
Colitis Ischaemic
56 reports
- Hyperpyrexia
Hyperpyrexia
54 reports
- Pyrexia 51
Pyrexia
51 reports
What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.
Reports over time
Adverse-event reports filed for baloxavir marboxil each year to the FDA Adverse Event Reporting System (FAERS).
Year-to-year volume tracks usage, prescribing, and scrutiny, not a change in per-patient risk. Source: FDA FAERS.
Where baloxavir marboxil sits
baloxavir marboxil has more FDA adverse-event reports than 13% of the drugs FAERS tracks. A high position reflects how widely a drug is used and watched, not how dangerous it is.
Percentile across all drugs PlainMeds tracks by FAERS report volume. The dot is baloxavir marboxil; the line is the median (50th percentile).
FDA Adverse Event Report Analysis
Detailed analysis of 2,164 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2017–2025.
Total Reports
2,164
Reports Mentioning Death
130
6.0% of reports — not proof of cause
Hospitalization Reports
417
Top Indication
Influenza
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 4 | DIARRHOEA | 129 |
| 5 | VOMITING | 120 |
| 6 | PNEUMONIA | 111 |
| 8 | NAUSEA | 70 |
| 9 | RASH | 61 |
| 10 | HEADACHE | 58 |
| 11 | INFLUENZA | 57 |
| 12 | COLITIS ISCHAEMIC | 56 |
| 13 | HYPERPYREXIA | 54 |
| 14 | PYREXIA | 51 |
| 15 | URTICARIA | 42 |
| 16 | COUGH | 40 |
| 17 | ANAPHYLACTIC REACTION | 38 |
| 18 | DIZZINESS | 38 |
| 19 | LOSS OF CONSCIOUSNESS | 38 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
Xofluza can cause allergic reactions like anaphylaxis. Get medical help right away if you have trouble breathing, hives, or swelling. Xofluza is not for children under 5 years old because it may not work as well in this age group. Xofluza does not prevent bacterial infections, which can happen with the flu. See a doctor if you think you have a bacterial infection.
Known Drug Interactions
7 DRUG INTERACTIONS Avoid coadministration of XOFLUZA with dairy products, calcium-fortified beverages, polyvalent cation-containing laxatives, antacids, or oral supplements (e.g., calcium, iron, magnesium, selenium, or zinc). Avoid coadministration of XOFLUZA with dairy products, calcium-fortified beverages, polyvalent cation-containing laxatives, antacids, or oral supplements (e.g., calcium, iron, magnesium, selenium, or zinc).
Mechanism: Zinc can bind to this medicine in your stomach and prevent it from being absorbed into your body. This makes the medicine less effective at treating the flu.
What to do: Do not take this medicine at the same time as supplements containing zinc. Avoid these products during your treatment.
7 DRUG INTERACTIONS Avoid coadministration of XOFLUZA with dairy products, calcium-fortified beverages, polyvalent cation-containing laxatives, antacids, or oral supplements (e.g., calcium, iron, magnesium, selenium, or zinc). Avoid coadministration of XOFLUZA with dairy products, calcium-fortified beverages, polyvalent cation-containing laxatives, antacids, or oral supplements (e.g., calcium, iron, magnesium, selenium, or zinc).
Mechanism: Selenium can attach to the medicine in your digestive system and stop it from getting into your bloodstream. This prevents the drug from working correctly.
What to do: Avoid taking selenium supplements at the same time as this medication. Talk to your doctor about when it is safe to take your supplements.
This is a plain-language summary of interactions documented in FDA labeling, not individualized advice. Ask a pharmacist or prescriber before combining medications.
Common Questions
How quickly does Xofluza work?
Can I take Xofluza if I'm allergic to eggs?
Can Xofluza prevent me from spreading the flu to others?
Can I take Xofluza with other medicines?
What if I start feeling worse after taking Xofluza?
Is there a generic version of Xofluza?
How effective is Xofluza?
Can I get the flu again even if I take Xofluza?
Does Xofluza interact with the flu shot?
What should I do if someone in my family has the flu?
What are the common side effects of baloxavir marboxil?
Does baloxavir marboxil interact with other medications?
What drug class is baloxavir marboxil?
Is baloxavir marboxil safe during pregnancy?
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What the FDA Data Shows for baloxavir marboxil
The FDA label for baloxavir marboxil (sold under brand names such as Xofluza) classifies it as a prescription-only medication in the Endonuclease Inhibitor (Antiviral) class. Xofluza is used to treat the flu in people 5 years and older. Official labeling lists 6 commonly reported side effects, including Diarrhea, Bronchitis, Nausea.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 2,164 voluntary reports. The database also lists 2 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated moderate severity. NADAC pricing from CMS.
Report counts do not establish causation, a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice, always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: August 22, 2025
Read our methodology - how this data is sourced, computed, and verified.
Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled and last refreshed May 2026. See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a correction.
All federal data sources used on this page
- FDA Orange Book - approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed - NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) - post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm - standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files - federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database - current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages