If you have influenza (flu), your doctor might suggest Xofluza as a treatment option for you. Similarly, if you’ve been exposed to someone with the flu, your doctor might suggest taking Xofluza. This is a prescription drug that’s used to treat and prevent flu in adults and certain children.

The active ingredient in Xofluza is baloxavir marboxil. (An active ingredient is what makes a drug work.) Xofluza belongs to a class of drugs called influenza virus PA endonuclease inhibitors. It comes in two forms. One is an oral tablet you’ll swallow, and the other is granules for suspension. (A pharmacist uses the granules to make a liquid solution that you’ll swallow.)

This article describes the dosages of Xofluza, as well as its strengths and how to take it. To learn more about Xofluza, see this in-depth article.

Note: This article covers Xofluza’s usual dosages, which are provided by the drugmaker. But when taking Xofluza, always take the dosage your doctor prescribes.

Xofluza’s dosage is based on body weight in kilograms (kg) and is taken once. For reference, 1 kg equals about 2.2 pounds (lb).

Note: Xofluza’s dosing chart below highlights the basics of Xofluza’s dosage for treating or preventing flu. Be sure to read on for more details.

Body weightDose
less than 20 kg2 milligrams per kg (mg/kg)
20 kg to less than 80 kg40 mg
80 kg or more80 mg

What are the forms of Xofluza?

Xofluza is available as an oral tablet that you’ll swallow, and granules for suspension. Using the granules, a pharmacist makes a liquid solution that you’ll swallow.

What strengths does Xofluza come in?

Xofluza oral tablets are available in 40-mg and 80-mg strengths. The granules for suspension are available in a strength of 40 mg per 20 milliliters (mL). (You can also write this as 2 mg/mL.)

What are the usual dosages of Xofluza?

The information below describes dosages that are commonly used or recommended. But be sure to take the dosage your doctor prescribes for you. They’ll determine the best dosage to fit your needs.

Dosage of Xofluza oral tablets in adults

The following table shows the dosages to prevent flu and treat flu in adults using Xofluza oral tablets. The dosages are based on body weight in kg.

Body weight in kgApproximate body weight in lbDoseFrequency
20 kg to less than 80 kg44 lb to less than 176 lb40 mgonce
80 kg or more176 lb or more80 mgonce

Dosage of Xofluza granules for suspension in adults

The following table shows the dosages to prevent and treat flu in adults using Xofluza granules for suspension. The dosages are based on body weight in kg.

Body weight in kgApproximate body weight in lbDoseAmount of solutionFrequency
less than 20 kgless than 44 lb2 mg/kg*variesonce
20 kg to less than 80kg44 lb to less than 176 lb40 mg20 mLonce
80 kg or more176 lb or more80 mg40 mLonce

* Read the question directly below to learn how to calculate a dose of 2 mg/kg for a particular body weight.

What’s the dosage of Xofluza for children?

Xofluza is approved for use in children ages 5 years and older to treat or prevent flu. Children’s dosage is the same as that in adults. See the recommended Xofluza dosage for adults in the two tables directly above.

This example will help you understand how a dose of 2 mg/kg of Xofluza granules for suspension is calculated. Assume a child weighs 18 kg (about 40 lb). Using 2 mg/kg, the child’s dose would be 36 mg. Xofluza oral suspension contains 2 mg of drug per mL of solution. So, to administer a 36-mg dose, you’d give 18 mL of the suspension.

For treating flu, you should take Xofluza within 48 hours of the start of flu symptoms. For preventing flu, take it as soon as possible after you’ve been exposed to someone with it.

You’ll take a Xofluza oral tablet by swallowing it. Using the granules for suspension, your pharmacist will make a liquid solution. You’ll need to swallow this solution within 10 hours after the pharmacist mixes it.

You can take Xofluza with or without food. But, you should avoid consuming the following products when taking Xofluza:

  • dairy products
  • drinks containing calcium
  • laxatives
  • antacids
  • supplements containing calcium, magnesium, selenium, or zinc

If you have trouble swallowing tablets, your doctor might prescribe the granules for suspension. (Using the granules, your pharmacist makes a liquid solution form of Xofluza.) Or you can check out this article for tips on taking tablets more easily.

For information on the expiration, storage, and disposal of Xofluza, see this article.

Accessible drug containers and labels

If you find it hard to read the prescription label on your medication, tell your doctor or pharmacist. Some pharmacies provide medication labels that:

  • have large print or use braille
  • feature a code you can scan with a smartphone to change the text to audio

Your doctor or pharmacist may be able to recommend pharmacies that offer these accessibility features if your current pharmacy doesn’t.

If you have trouble opening medication bottles, let your pharmacist know. They may be able to supply Xofluza in an easy-open container. They also may have tips to help make it simpler to open the drug’s container.

Do not take more Xofluza than your doctor prescribes as this can lead to serious side effects.

What to do in case you take too much Xofluza

Call your doctor right away if you think you’ve taken too much Xofluza. You can also call 800-222-1222 to reach the American Association of Poison Control Centers or use its online resource. But if you have severe symptoms, immediately call 911 (or a local emergency number) or go to the nearest emergency room.

Below are answers to some questions commonly asked about Xofluza’s dosage.

Can I take my Xofluza dose if it’s been longer than 48 hours since my symptoms started?

No, you shouldn’t. That’s because you should take Xofluza within 48 hours of the start of flu symptoms. This is the timeframe that was used in Xofluza’s studies. So, it isn’t known if Xofluza would be effective 48 hours after of the start of symptoms.

If you’ve had flu symptoms for more than 48 hours, call your doctor. They can decide whether other treatments might be helpful. If you didn’t take your Xofluza dose within 48 hours of the start of flu symptoms, let your doctor know. They can determine the best way to treat your symptoms.

What is the dose of Xofluza for children younger than 5 years of age?

Xofluza isn’t approved for use in children under 5 years of age. It isn’t known if any dose of Xofluza is safe and effective in this age group.

For a child younger than 5 years of age, call your pediatrician right away if the child has flu symptoms. The doctor can determine the best treatment for the child’s symptoms.

The sections above describe the usual dosages provided by the drugmaker. If your doctor recommends Xofluza for you, they’ll prescribe the dosage that’s right for you.

Remember, you should not change your dosage of Xofluza without your doctor’s recommendation. Only take Xofluza exactly as prescribed. Talk with your doctor if you have questions or concerns about your current dosage.

Here are some examples of questions you may want to ask your doctor:

  • Can I take a second dose of Xofluza if it isn’t working well enough for me?
  • I understand it’s OK to take food with Xofluza and that some products should be avoided. Which products should I avoid, and how long do I need to wait after taking Xofluza to have these products?
  • Can I get a prescription for Xofluza’s granules for suspension if I have trouble swallowing tablets?
  • How do I measure the amount of Xofluza oral suspension to give?

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Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.