Xofluza (Baloxavir Marboxil) Oral: Uses, Side Effects

What Is Xofluza?

Xofluza (baloxavir marboxil) is an oral prescription drug used to prevent or treat influenza A or B (the seasonal flu). It is available as a tablet or suspension that is taken by mouth.

Xofluza is in a drug class called antivirals, or more specifically, polymerase acidic endonuclease inhibitors. It works by preventing the flu virus from growing and spreading in the body.

Drug Facts

Generic Name: Baloxavir marboxil

Brand Name(s): Xofluza

Drug Availability: Prescription

Administration Route: Oral

Therapeutic Classification: Antiviral; Polymerase acidic endonuclease inhibitor

Available Generically: No

Controlled Substance: N/A

Active Ingredient: Baloxavir marboxil

Dosage Form(s): Tablet, suspension

What Is Xofluza Used For?

The Food and Drug Administration (FDA) approved Xofluza for use in adults and adolescents 12 and older (weighing at least 88 pounds) to:

  • Treat uncomplicated flu with symptoms occurring for 48 hours (two days) or less in otherwise healthy people or those at high risk of developing flu-related complications.
  • Prevent flu after being in contact with someone who has the flu.

Xofluza does not treat bacterial infections (such as pneumonia) that may occur as a complication of the flu. It also does not treat other viral infections, such as the common cold or COVID-19.

How to Take Xofluza

If you are prescribed Xofluza, make sure to read the prescription label and the information leaflet that comes with your prescription. Consult your healthcare provider if you have any questions.

Use Xofluza exactly as directed by your healthcare provider. Xofluza is usually taken as one dose, with or without food. The dose will be based on your weight. Your healthcare provider will either prescribe Xofluza’s tablet form or oral suspension formulation.

If you are taking the Xofluza suspension:

  • Take it as soon as possible after mixing it. Do not take the mixture if more than 10 hours have passed.
  • Use a measuring device, such as an oral syringe or measuring cup, to ensure accurate dosing.

Do not take Xofluza with dairy products, such as milk, yogurt, cheese, or calcium-fortified foods or drinks. Also, avoid taking Xofluza with medications that contain aluminum, calcium, magnesium, iron, selenium, or zinc. These ingredients are commonly found in antacids, vitamins, and laxatives.

Follow your healthcare provider’s instructions on how to take Xofluza:

  • If you are taking Xofluza to treat your flu, take it at the first sign of symptoms (e.g., fever, chills, sore throat, muscle pain, and nasal symptoms). Xofluza is effective when taken in the first 48 hours (two days) of symptoms.
  • If you are taking Xofluza to prevent the flu, take it as soon as possible after you have been in contact with someone who has it.

Contact your healthcare provider if your symptoms worsen or do not improve.


You can store Xofluza tablets and suspension at room temperature (68 to 77 degrees F). However, the suspension should not be kept at room temperature for more than 10 hours. If you don’t take it within 10 hours of mixing, discard the medication. Keep Xofluza out of sight and out of the reach of children and pets.

How Long Does Xofluza Take to Work?

In clinical trials, people who took Xofluza felt better after about two days compared with people who took a placebo.

What Are the Side Effects of Xofluza?

This is not a complete list of side effects and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your healthcare provider. You may report side effects to the FDA at fda.gov/medwatch or 1-800-FDA-1088.

Like other medications, Xofluza can cause side effects. Tell your healthcare provider about any side effects you experience while taking this medication.

Common Side Effects

The most common side effects of Xofluza are:

  • Bronchitis: Symptoms may include cough and shortness of breath.
  • Diarrhea
  • Headache
  • Nausea
  • Sinusitis: Symptoms may include headache, facial pain, and runny or stuffy nose.

Severe Side Effects

Call your healthcare provider right away if you have serious side effects. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency.

Hypersensitivity reaction or anaphylaxis can occur with Xofluza. Symptoms may include:

Any symptom of an allergic reaction requires emergency medical attention.

Long-Term Side Effects

For the most part, many people tolerate Xofluza well, especially since it is only one dose. However, delayed side effects have been noted on rare occasions. These include:

Report Side Effects

Xofluza may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your healthcare provider may send a report to the FDA’s MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Xofluza Should I Take?

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The dose of this medicine will be different for different patients. Follow your doctor’s orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage form (tablets):

    • For the flu:

      • Adults and children 12 years of age and older weighing 80 kilograms (kg) or more—2 tablets of 40 milligrams (mg) taken as a single dose for a total of 80 mg per day.
      • Children 12 years of age and older weighing 40 kg to 79 kg—2 tablets of 20 milligrams (mg) taken as a single dose for a total of 40 mg per day.
      • Children younger than 12 years of age or weighing less than 40 kg—Use and dose must be determined by your doctor.


Although Xofluza is safe for older adults (65 and older) to take, nausea may occur more often in this age group. Be aware that if you are older you might be more likely to experience the side effects of this medication.

Sometimes, kidney or liver impairment can affect what dose of medication you should take. In this case, people with mild or moderate kidney or liver problems can usually take Xofluza at the normal dose. If you have severe kidney or liver problems, consult your healthcare provider.

Xofluza comes in both tablet form and as an oral suspension. It may also be given through a feeding tube.

Missed Dose

Xofluza is taken as one dose and does not have a regular dosing schedule.

Overdose: What Happens If I Take Too Much Xofluza?

There is no specific antidote or treatment for overdosing on Xofluza.

What Happens If I Overdose on Xofluza?

If you think you or someone else may have overdosed on Xofluza, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn’t breathing after taking Xofluza, call 911 immediately.


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It is very important that your doctor check your or your child’s progress after treatment to make sure that the infection is cleared up completely, and to allow your doctor to check for any unwanted effects.

If your or your child’s symptoms do not improve or if they become worse, check with your doctor.

This medicine may cause serious allergic reactions, including anaphylaxis, angioedema, or certain skin conditions. These reactions can be life-threatening and require immediate medical attention. Call your doctor right away if you or your child have a rash, itching, blistering, peeling, or loosening of the skin, fever or chills, trouble breathing or swallowing, or any swelling of your hands, face, mouth, or throat while you are using this medicine.

This medicine is not a substitute for an annual flu shot. It also will not keep you or your child from getting a bacterial infection that starts with flu-like symptoms.

What Are Reasons I Shouldn’t Take Xofluza?

Xofluza is not appropriate for everyone.

Do not take Xofluza if you:

  • Are allergic to baloxavir marboxil or any of the inactive ingredients in Xofluza
  • Are pregnant or breastfeeding
  • Have complicated illness, a severely compromised immune system, or are hospitalized

What Other Medications May Interact With Xofluza?

Tell your healthcare provider about all of your medications, including prescription and over-the-counter drugs, vitamins, or herbal supplements. 

Because these products may interfere with how well Xofluza works, Xofluza should not be taken with:

  • Dairy products (e.g., milk, cheese, yogurt, or calcium-fortified drinks or foods)
  • Laxatives, antacids, or vitamin/mineral supplements that contain calcium, iron, magnesium, selenium, or zinc

Do not take Xofluza within several weeks of the intranasal live attenuated influenza vaccine (LAIV). Taking Xofluza within this timeframe of receiving an intranasal LAIV has not been evaluated, but concurrent use may decrease the vaccine’s effectiveness.

Other drug interactions may occur with Xofluza. Consult your healthcare provider for a complete list of drug interactions.

What Medications Are Similar?

Xofluza is a prescription antiviral drug used to prevent or treat seasonal flu in adults and adolescents 12 and older.

Other antivirals used for this indication include:

  • Rapivab (peramivir); Rapivab is given as an injection into the vein for adults and children 2 years and older. It is used for treatment only, not for prevention.
  • Relenza (zanamivir): Relenza is administered as an inhaler for adults and children 7 years and older.
  • Tamiflu (oseltamivir phosphate): Tamiflu is given as an oral capsule or suspension for adults, children, and infants 14 days and older.

The Centers for Disease Control and Prevention (CDC) recommends that everyone 6 months or older (with rare exceptions) get a flu vaccine yearly to help prevent seasonal flu. Xofluza does not take the place of a flu vaccine.

This list is a list of drugs also prescribed for the flu. It is NOT a list of drugs recommended to take with Xofluza. Ask your pharmacist or a healthcare provider if you have questions.

Frequently Asked Questions

  • What is Xofluza used for?

    Xofluza is a prescription medication used to prevent or treat seasonal flu in adults and adolescents ages 12 and older.

  • How does Xofluza work?

    Xofluza prevents the flu virus from spreading in the body and shortens the length of time that your symptoms last.

  • What drugs should not be taken with Xofluza?

    Xofluza should not be taken with medications (such as vitamin/mineral supplements, laxatives, or antacids) containing calcium, iron, magnesium, selenium, or zinc. Xofluza should not be taken with dairy products, such as milk, cheese, yogurt, or foods or drinks fortified with calcium. Xofluza should not be given within several weeks of the intranasal live attenuated influenza vaccine.

  • How long does it take for Xofluza to work?

    People who take Xofluza usually feel better in about two days. If symptoms worsen or do not improve, contact your healthcare provider.

  • What are the side effects of Xofluza?

    The most common side effects are nausea, headache, and diarrhea. Serious side effects include allergic reactions. Symptoms of hives, shortness of breath, swelling, or skin lesions can indicate an allergic reaction and require emergency medical attention.

How Can I Stay Healthy While Taking Xofluza?

Before taking Xofluza, discuss your medical history and all medications you take with your healthcare provider. 

Here are some measures you can take every day to help reduce the spread of flu:

  • Cover your nose and mouth with a tissue when you cough or sneeze, then discard the tissue and wash your hands.
  • Avoid touching your face; germs can enter through the eyes, nose, and mouth.
  • Avoid people who are sick. If you are sick, stay separated from others as much as possible.
  • Wash hands often and thoroughly with soap and water. If soap is not available, use a hand sanitizer with at least 60% alcohol.
  • Clean and disinfect contaminated objects and surfaces in the home.
  • Stay home for at least one day (24 hours) after the fever is gone (without the need for medication to lower the fever).

If you have the flu, symptoms may include:

  • Fever
  • Cough
  • Sore throat
  • Body aches
  • Headache
  • Nasal symptoms

Ask your healthcare provider or pharmacist for advice on methods to help improve your symptoms in addition to taking Xofluza. Rest and drink plenty of fluids.

Medical Disclaimer

Verywell Health’s drug information is meant for educational purposes only and is not intended to replace medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.