Key takeaways:
Xofluza (baloxavir marboxil) is an antiviral medication that can treat or prevent the flu in adults and children ages 5 years and older. It comes as an oral tablet, liquid suspension, and granule packet.
Xofluza is a one-and-done dose that’s tailored to your body weight. You’ll take the same amount whether you’re using it to treat the flu or help keep it away.
It’s best to start Xofluza as soon as possible. You should take it within 48 hours (2 days) of flu symptoms first appearing or after coming in contact with someone who has the flu.
There are ways to save on Xofluza. If you’re eligible, a manufacturer savings card can help you get Xofluza for as little as $35 per fill.
Save on related medications
A sudden fever, fatigue, and muscle aches — these are all possible symptoms of seasonal influenza, also known as the flu. They can come on quickly and last more than a week. So finding quick treatment is a priority if you end up being exposed to this respiratory virus.
Xofluza (baloxavir marboxil) is one flu medication your healthcare professional may recommend. Xofluza is an FDA-approved antiviral that can treat or prevent the flu with a single dose. Many adults and children can take it.
But, like with all medications, Xofluza’s safety and effectiveness hinges on the right dose. This Xofluza dosage guide reviews recommended doses for flu treatment and prevention. But make sure to speak to your prescriber about the best dosage for you — it may be different from what’s mentioned here.
What dosage forms of Xofluza are available?
Xofluza is available as an oral tablet and a liquid. The tablet comes in two doses: 40 mg and 80 mg. Liquid Xofluza is available as a 2 mg/mL suspension and as 30 mg and 40 mg granule packets that you mix with water.
Regardless of form, Xofluza is a one-time, oral medication. This makes it convenient to take, but timing is key. You should take it as soon as possible within 48 hours (2 days) of flu symptoms first appearing. So, if you start feeling sick or you come into contact with someone who has the flu, it’s important to see a healthcare professional for a flu test as soon as possible.
You can take Xofluza with or without food. But there are a few things to keep in mind if you’re taking Xofluza with a meal or snack. For example, don’t take it at the same time as dairy products or drinks fortified with calcium. Oral supplements or medications containing iron, magnesium, or zinc can also pose an issue. These interactions can make Xofluza less effective.
What’s the typical Xofluza dosage for adults?
Xofluza can be prescribed for flu treatment and flu prevention in adults.
Flu treatment
If you’re prescribed Xofluza, your healthcare professional should calculate your dose based on your body weight in kilograms (kg). These are the recommended Xofluza dosages to treat flu in adults.
Body weight | Dose (tablet) | Dose (liquid) | Dose (granule packet) |
|---|---|---|---|
20-79.9 kg (44-175 lbs) | One 40 mg tablet | 40 mg (20 mL) taken as a single dose | One 40 mg packet |
80 kg (176 lbs) or greater | One 80 mg tablet | 80 mg (40 mL) taken as a single dose | Two 40 mg packets |
For Xofluza liquid doses, it’s important to use a measuring device, such as an oral syringe, to measure an exact dose. Household spoons and other similar tools often provide incorrect or inaccurate doses.
For Xofluza packets, mix the packet with 15 mL to 20 mL of water (about 3 to 4 teaspoons) right before taking your dose.
Good to know: If you’re prescribed 80 mg of liquid Xofluza, your pharmacist will provide you with two bottles of medication. Smaller, 40 mg doses only need one bottle. But regardless of size, the pharmacist needs to prepare the liquid for you. You should take it within 10 hours of picking it up from the pharmacy. The pharmacist can also add flavoring to make the medication more appealing.
Flu prevention
Recommended Xofluza dosages for flu prevention are the same as flu treatment. These are detailed in the table above.
What’s the typical Xofluza dosage for children?
Xofluza pediatric doses are similar to adult doses. Children who are at least 5 years old may be able to take Xofluza if it’s been less than 48 hours since their flu symptoms started or they came in contact with someone who had the flu.
Xofluza side effects: Learn what side effects are possible while taking Xofluza (baloxavir marboxil) and how to manage them if they occur.
How does Xofluza work? Find answers to this and more common questions about Xofluza.
Tips for taking Xofluza: GoodRx pharmacists share when to take it, what to expect, and how to save time and money on your prescription.
Flu treatment
Like adults, Xofluza dosages for kids are based on body weight. But depending on how much your child weighs, your prescriber may have to do some extra calculations to figure out their dose.
Body weight | Dose (tablet) | Dose (liquid) | Dose (granule packets) |
|---|---|---|---|
Less than 20 kg (44 lbs) | Do not use | 2 mg/kg of body weight, taken as a single dose | One 30 mg packet (Minimum weight for taking the packets is 15 kg, or 33 lbs) |
20-79.9 kg (44-175 lbs) | One 40 mg tablet | 40 mg (20 mL) taken as a single dose | One 40 mg packet |
80 kg (176 lbs) or greater | One 80 mg tablet | 80 mg (40 mL) taken as a single dose | Two 40 mg packets |
You won’t need to figure out a dosage on your own. But weight-based Xofluza dosing can still be hard to visualize. If your child weighs 10 kg (22 lbs), they would need 20 mg of liquid Xofluza. This amounts to 10 mL of medication. Your pharmacist should provide you with a measuring device so you can administer the prescribed dose.
Flu prevention
If your child comes in close contact with someone who has the flu, they can take Xofluza for flu prevention if they’re at least 5 years old. The recommended doses for children are the same as for flu treatment, listed above.
Keep in mind: Xofluza isn’t approved for use in children younger than 5 years old. Younger kids shouldn’t take Xofluza because there is a risk of “treatment-emergent resistance.” In other words, Xofluza may not work as well and the flu virus can become harder to treat in the future. Xofluza’s safety and effectiveness in younger kids also isn’t well established. Tamiflu (oseltamivir) is a better oral option for young kids.
Are there any Xofluza dosage adjustments for medical conditions?
Not usually. Xofluza doesn’t have recommended dosage adjustments for specific medical conditions. This includes kidney and liver problems.
However, some people should avoid taking Xofluza altogether. If you’ve had an allergic reaction in the past to any of Xofluza’s ingredients, you shouldn’t take it. Pregnant women should also avoid taking Xofluza out of caution. Tamiflu is preferred during pregnancy.
What happens if you miss a dose of Xofluza?
In most cases, missed doses shouldn’t be an issue. Xofluza is taken as a single dose. Repeat doses aren’t usually necessary.
Still, try to take your dose as soon as possible — especially within 48 hours of developing flu symptoms or after coming in contact with someone who has the flu. If you don’t take Xofluza within the recommended time frame, the medication may be less effective.
What should you do if you take too much Xofluza?
Xofluza overdoses aren’t common. But they could technically happen.
If you think you took too much Xofluza (or gave your child too much), call your healthcare team as soon as you can. They’ll aim to address any symptoms or side effects you may be experiencing, such as diarrhea or nausea. You can also contact Poison Control online or at 1-800-222-1222.
If you feel that you’re having serious or life-threatening symptoms, go to the nearest ER right away.
How to save on Xofluza
There are ways to save on Xofluza, which is only available as a brand-name medication. GoodRx can help you navigate between copay savings cards and other discounts to save money on your prescription.
Save with a copay savings card: If you have commercial insurance, you may be eligible to pay as little as $35 for Xofluza using a savings card from the manufacturer. A $50 cash pay offer is also available if you’re not using insurance.
Save with GoodRx: GoodRx can help you save over 20% off the average retail price of Xofluza. Xofluza’s price at certain pharmacies is as low as $168.65 with a free GoodRx discount.
Frequently asked questions
No, Xofluza isn’t an antibiotic. It’s an antiviral medication that treats and prevents the flu by stopping the influenza virus from replicating. Antibiotics don’t treat viruses like the flu.
Not exactly. While both medications are antivirals, Xofluza and Tamiflu work in different ways to fight the flu. One isn’t necessarily stronger than the other. Your healthcare professional can help decide which option is better for you.
Xofluza is meant to be taken as a single dose to treat or prevent the flu. It usually isn’t recommended to take it again within the same month unless your prescriber advises it. If you get sick again or your symptoms aren’t improving, contact your prescriber before taking another dose. They can review your situation, confirm whether another treatment is needed, and recommend the safest next steps for you.
No, Xofluza isn’t an antibiotic. It’s an antiviral medication that treats and prevents the flu by stopping the influenza virus from replicating. Antibiotics don’t treat viruses like the flu.
Not exactly. While both medications are antivirals, Xofluza and Tamiflu work in different ways to fight the flu. One isn’t necessarily stronger than the other. Your healthcare professional can help decide which option is better for you.
Xofluza is meant to be taken as a single dose to treat or prevent the flu. It usually isn’t recommended to take it again within the same month unless your prescriber advises it. If you get sick again or your symptoms aren’t improving, contact your prescriber before taking another dose. They can review your situation, confirm whether another treatment is needed, and recommend the safest next steps for you.
The bottom line
Xofluza (baloxavir marboxil) is an antiviral medication that helps treat and prevent the flu with a single dose. Most people ages 5 years and older can take it, but exact dosages are based on body weight. The recommended Xofluza dosage for adults is 40 mg or 80 mg as one dose, depending on your body weight. You should take Xofluza as soon as possible within 48 hours (2 days) of flu symptoms first appearing or after coming in contact with someone who has the flu.
Why trust our experts?
References
Genentech. (2025). Xofluza- baloxavir marboxil tablet, film coated; Xofluza- baloxavir marboxil granule, for solution; Xofluza- baloxavir marboxil granule, for suspension [package insert]. DailyMed.
National Institute of Allergy and Infectious Diseases. (2024). Influenza.
