An Overview of XOFLUZA

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On October 24, 2018 the U.S. Food and Drug Administration (FDA) approved a new drug to treat influenza. XOFLUZA (baloxavir marboxil) is the first new drug approved to treat influenza in 20 years.

XOFLUZA is made by the same pharmaceutical company that makes Tamiflu, another medicine to treat influenza. However, the two drugs are different. Here are the key facts about XOFLUZA you should know.

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XOFLUZA (baloxavir marboxil) is a newly approved antiviral medication your doctor can prescribe to treat influenza (the flu). Drugs like XOFLUZA can help make your flu symptoms less intense if you take them within the first 48 hours you are sick.

In clinical trials, people with the flu who took XOFLUZA within the first 24 hours of being ill felt better sooner than people who took a placebo (a pill with no medication) or took an antiviral later (24-48 hours or more after symptoms started).

Should You Still Get the Flu Vaccine?

Your doctor will only prescribe XOFLUZA if you are sick with the flu. The medication will not prevent you from getting sick, so your doctor will still likely recommend you get the yearly influenza vaccine (unless you have a medical reason why you can't).

Who It's for

Your doctor will want to talk to you about your symptoms and may want to test you for influenza before prescribing XOFLUZA. The medication will work best if you meet the following criteria:

  • you are over 12 years old and
  • you have an uncomplicated case of the flu and
  • you haven't had flu symptoms for longer than 48 hours.

The medication won't be the right choice for everyone. For example, XOFLUZA is not for someone who is sick enough to be in the hospital or is allergic to certain medications.

You should not take XOFLUZA if you are allergic or sensitive to baloxavir marboxil or any of the other ingredients in the medication.


There are two dosages of XOFLUZA available. If you are 12 years or older, your doctor will prescribe XOFLUZA based on how much you weigh.

Recommendations by Weight

Xofluza is dosed according to weight. For people 12 years and older weighing:

  • 88 lbs (40kg) to 176 lbs (80 kg): One-time 40 mg dose 
  • 176 lbs (80 kg) or more: One-time 80 mg dose


The FDA granted XOFLUZA's clinical trials Priority Review, meaning the drug went through the process of approval more quickly than usual because the FDA deemed it an important medication for public health.

While the process is faster, the review is still rigorous. Researchers and drug manufacturers must demonstrate a drug is effective and safe for people to take before the FDA will approve it.

XOFLUZA underwent two randomized clinical trials. A total of 1,832 patients were part of the testing. Some took XOFLUZA, some took another type of antiviral used to treat the flu, and the others got a placebo pill. There were 910 people in the trial who took XOFLUZA. Most of them were adults (92 percent).

The trials tested how well XOFLUZA worked compared to other antivirals. In the first trial, it reduced flu symptoms more quickly than other antivirals. In the second trial, there was no difference. The researchers also determined that XOFLUZA does not treat other illnesses caused by a virus. It should only be used to treat people who have influenza.

XOFLUZA does not treat illnesses caused by bacteria. If someone has flu-like symptoms caused by a bacterial infection, they should not take XOFLUZA. Antiviral medications will not help someone with an infection caused by bacteria feel better and won't prevent complications from bacterial infections.

Since there are many different strains of the virus that can cause influenza, patients should know that XOFLUZA might not work as well for one virus compared to another.

During the clinical trials, researchers took note of any side effects or complications people in the trial experienced when taking XOFLUZA. Then, they figured out if the symptoms reported were caused by taking XOFLUZA or another reason. Some people in the trial reporting having symptoms even though they were taking a placebo.

Before taking XOFLUZA, make sure your doctor knows about any other health conditions you have (acute and chronic).

Let your doctor know if you are pregnant or breastfeeding before starting a medication or receiving a shot (vaccine) to prevent or treat influenza. Your doctor might decide the benefits of being protected from catching the flu while you are pregnant (which can lead to serious complications) outweighs any potential side effects from the medication.

Side Effects

Some people in the clinical trial reported side effects when they were taking XOFLUZA. Clinical trials are different than using the drug in actual everyday life.

The most commonly reported side effects by people in the clinical trial for XOFLUZA were:

It's possible that someone taking XOFLUZA might experience other side effects than the ones reported by people in the clinical trial. If you are concerned about side effects from XOFLUZA, talk to your doctor.

Tell your doctor about all the other medications you are taken, even if they are only over-the-counter vitamins, supplements, or probiotics. Calcium-containing products can affect how well the body absorbs certain medications or can make the medicines less effective.

Your doctor might tell you to avoid taking XOFLUZA with food, medication, or supplements that have calcium in them, including dairy products, laxatives, antacids, or vitamin supplements.

XOFLUZA vs. Other Options

In the clinical trials, researchers compared XOFLUZA with another drug used to treat influenza symptoms called oseltamivir (Tamiflu). While the two drugs work in a similar way, you should know how they are different. Your doctor will help you decide if XOFLUZA is a good choice for you or if you should try another antiviral to treat your flu symptoms.

Tamiflu and XOFLUZA are both antiviral drugs that can be used to shorten the duration of flu symptoms. Both drugs are only used to treat viral illness; they will not work if you are sick from a bacterial infection. Both Tamiflu and XOFLUZA work best if you take them within the first day or so after you get the flu. They won't help lessen your symptoms if you take them after the first 48 hours you are sick. The side effects reported for both Tamiflu and XOFLUZA are similar.

Tamiflu and XOFLUZA also have some key differences you should know about:

  • XOFLUZA is only available for people over 12 years old. Tamiflu can be prescribed for infants as young as two weeks old.
  • You only need to take one dose of XOFLUZA. Tamiflu requires several doses taken over the course of a few days to a couple of weeks.
  • Tamiflu has been approved for women who are pregnant. You should tell your doctor if you are pregnant and they will help you decide if you should take XOFLUZA.
  • If you catch the flu and need to be hospitalized, XOFLUZA may not be right for you. Tamiflu can be used to treat more serious influenza cases. Your doctor, pharmacist, or other medical professional involved in your care will help decide which treatment is best for you.

The cost of Tamiflu and XOFLUZA will depend on several factors, including health insurance or company coupons for reducing the cost of your prescription.

A Word From Verywell

If you catch the flu this year, your doctor might recommend XOFLUZA. You can find out more on XOFLUZA's website. Ask your doctor if you are worried about side effects or aren't sure if XOFLUZA is right for you.

Find out more about how influenza spreads, what the symptoms of the flu are, how to tell if you have a cold or the flu, and what your options for treatment are.

You can also read up on how to prevent influenza with vaccines and other preventative measures like good hand hygiene. You can also learn about the other medications that work like XOFLUZA to treat the flu. Ask your doctor if you can take a medication like XOFLUZA to help lessen your flu symptoms and get you feeling better faster.

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Article Sources
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  3. Genentech, Inc. XOFLUZA: HIGHLIGHTS OF PRESCRIBING INFORMATION (PDF). Updated October 2019. 

  4. Ng KE. Xofluza (Baloxavir Marboxil) for the Treatment Of Acute Uncomplicated InfluenzaP T. 2019;44(1):9–11.

  5. Genentech USA, Inc. XOFLUZA (baloxavir Marboxil) Safety Profile. Published 2019.

  6. U.S. Food And Drug Administration (FDA). Drug Trial Snapshot: XOFLUZA. FDA Drug Approvals and Databases. Updated July 2019.

  7. Hayden FG, Sugaya N, Hirotsu N, et al. Baloxavir Marboxil for Uncomplicated Influenza in Adults and Adolescents. N Engl J Med. 2018;379(10):913-923. doi:10.1056/NEJMoa1716197


  9. U.S. Food And Drug Administration (FDA). Tamiflu: Consumer Questions and Answers. FDA Postmarket Drug Safety Information for Patients and Providers. Updated November 2017. 

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