What to Know About Xofluza Side Effects Before You Take It

Xofluza (baloxavir marboxil) is a single-dose antiviral medication used to treat influenza. Like all medications, it can cause side effects — though most people tolerate it well. Because Xofluza 80 Mg Dose Pack is taken as just one dose, any side effects you experience are usually short-lived.

This guide covers the common and serious side effects reported in clinical trials and FDA labeling, who may be more at risk, and when you should contact your doctor.

Common Side Effects of Xofluza 80 Mg Dose Pack

In clinical trials, the most frequently reported side effects of Xofluza were mild. According to FDA prescribing information, these include:

• Diarrhea — reported in about 3% of patients
• Bronchitis — reported in about 3% of patients
• Nausea — reported in about 2% of patients
• Sinusitis — reported in about 2% of patients
• Headache — reported in about 1% of patients

These side effects are generally mild and go away on their own within a day or two. Keep in mind that some of these symptoms — like headache and nausea — can also be caused by the flu itself, so it's not always clear whether Xofluza or the flu is responsible.

How Common Are Side Effects Compared to Other Flu Medications?

Xofluza's side effect profile is comparable to other antiviral flu treatments. For context, Tamiflu (oseltamivir) commonly causes nausea and vomiting at higher rates than Xofluza. Because Xofluza is a single dose rather than a five-day course, your total exposure to the medication is much shorter, which may reduce the chance of ongoing side effects. You can learn more about how Xofluza compares in our guide to Xofluza alternatives.

Serious Side Effects of Xofluza

Serious side effects are rare but important to know about. Contact your doctor or seek emergency medical attention if you experience any of the following after taking Xofluza:

• Allergic reactions (anaphylaxis) — Signs include difficulty breathing, swelling of the face, throat, or mouth, hives, or a severe rash. This is a medical emergency.
• Severe rash — Any widespread skin reaction that develops after taking the medication.
• Difficulty breathing — If you develop new or worsening breathing problems beyond typical flu symptoms.
• Swelling of the face, throat, or mouth — This can indicate a serious allergic reaction.

Xofluza does not carry a boxed warning (the FDA's most serious safety alert). However, allergic reactions can happen with any medication, so it's important to be aware of the signs.

Side Effects in Specific Populations

Children

Xofluza is approved for patients 5 years of age and older. In pediatric clinical trials, vomiting was reported more frequently in children than in adults. The 80 Mg Dose Pack is typically prescribed for patients weighing 80 kg or more, which generally applies to older teens and adults.

Pregnant or Breastfeeding Women

There is limited data on Xofluza use during pregnancy and breastfeeding. If you are pregnant, planning to become pregnant, or breastfeeding, talk to your doctor before taking Xofluza. They can help you weigh the benefits of treating the flu against any potential risks.

Older Adults

No specific dose adjustment is needed for older adults. Clinical trials included patients at high risk for flu complications, including older adults, and the side effect profile was similar to the general population.

People with Kidney or Liver Problems

According to the prescribing information, no dose adjustment is needed for patients with renal or hepatic impairment. However, always let your doctor know about any pre-existing conditions before taking a new medication.

How to Manage Common Side Effects

If you experience mild side effects after taking Xofluza 80 Mg Dose Pack, here are some practical tips:

• Diarrhea: Stay hydrated with water and clear fluids. Avoid heavy, greasy foods until it resolves. Over-the-counter anti-diarrheal medications like loperamide (Imodium) may help if symptoms are bothersome.
• Nausea: Eat small, bland meals. Ginger tea or crackers may help settle your stomach. If nausea is severe or accompanied by repeated vomiting, contact your doctor.
• Headache: Over-the-counter pain relievers like acetaminophen (Tylenol) or ibuprofen (Advil) are generally safe to take alongside Xofluza for headache relief. These can also help with flu-related body aches and fever.
• Bronchitis or sinusitis: These symptoms may overlap with or follow the flu itself. Rest, stay hydrated, and use a humidifier. If symptoms worsen or last more than a week, see your doctor to rule out a secondary bacterial infection.

When to Call Your Doctor

Contact your healthcare provider if you experience:

• Any signs of an allergic reaction (hives, swelling, difficulty breathing)
• Side effects that are severe or don't improve within a few days
• Flu symptoms that get worse after initially improving (this could indicate a secondary infection, not a Xofluza side effect)
• New symptoms that concern you after taking the medication

If you experience difficulty breathing, facial swelling, or signs of anaphylaxis, call 911 or go to the nearest emergency room immediately.

Final Thoughts

Most people who take Xofluza 80 Mg Dose Pack experience few or no side effects. The most common ones — diarrhea, bronchitis, nausea, sinusitis, and headache — are generally mild and short-lived. Serious allergic reactions are rare but require immediate medical attention.

If you're considering Xofluza for flu treatment, understanding the mechanism of action and potential drug interactions can also help you make an informed decision. And if you're ready to fill your prescription, Medfinder can help you find a pharmacy with Xofluza in stock near you.