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Baloxavir marboxil Side Effects

Medically reviewed by Last updated on Jul 1, 2022.

For the Consumer

Applies to baloxavir marboxil: oral tablet

Side effects requiring immediate medical attention

Along with its needed effects, baloxavir marboxil may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking baloxavir marboxil:

Less common

  • Chest tightness
  • cough producing mucus
  • difficulty breathing
  • fever
  • headache
  • muscle aches
  • sore throat
  • stuffy or runny nose
  • unusual tiredness or weakness

Incidence not known

  • Blistering, peeling, or loosening of the skin
  • bloody, black, or tarry stools
  • chills
  • cough
  • diarrhea
  • difficulty swallowing
  • dizziness
  • fast heartbeat
  • hives, itching, skin rash
  • hoarseness
  • joint or muscle pain
  • puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • red, irritated eyes
  • sores, ulcers, or white spots in the mouth or on the lips
  • voice changes

Side effects not requiring immediate medical attention

Some side effects of baloxavir marboxil may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Less common

Incidence not known

  • Seeing, hearing, or feeling things that are not there
  • vomiting

For Healthcare Professionals

Applies to baloxavir marboxil: oral tablet


Postmarketing reports: Angioedema (swelling of face, eyelids, tongue, and lips), rash, urticaria, erythema multiforme[Ref]


Common (1% to 10%): Diarrhea, nausea

Postmarketing reports: Vomiting, hematochezia, bloody diarrhea, melena, colitis, ischemic colitis[Ref]

Nausea was reported in 6% of elderly subjects compared to 1% of younger subjects (aged 18 to 64 years).[Ref]


Postmarketing reports: Anaphylactic reactions, anaphylactic shock, anaphylactoid reactions, anaphylaxis, hypersensitivity reactions[Ref]

Nervous system

Common (1% to 10%): Headache[Ref]


Postmarketing reports: Delirium, abnormal behavior, hallucinations


Common (1% to 10%): Bronchitis, sinusitis, nasopharyngitis

Frequency not reported: Dysphonia[Ref]

Frequently asked questions


1. "Product Information. Xofluza (baloxavir marboxil)." Roche Products Pty Ltd (2021):

2. "Product Information. Xofluza (baloxavir marboxil)." Genentech (2022):

3. "Product Information. Xofluza (baloxavir marboxil)." Roche Products Ltd (2022):

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.