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INREBIC® (fedratinib) is a prescription medicine used to treat adults with certain types of myelofibrosis (MF). It is not known if INREBIC is safe and effective in children.

Side Effects

Understanding the side effects of INREBIC: Image of female health care professional and man with stethoscope on his arm.

On this page:

    What’s the most important information to know about side effects?

    It’s important to understand the possible side effects of treatment. Talk to your doctor about any side effects that you may experience.

    Important information to know about INREBIC side effects: Image of man with his arm around woman's shoulder.

     

    INREBIC may cause serious side effects, such as encephalopathy (including Wernicke’s encephalopathy). A serious and sometimes fatal neurological problem called encephalopathy (including Wernicke’s encephalopathy) has happened in some people who take INREBIC.

    Wernicke’s encephalopathy is a neurologic emergency that can happen if you do not have enough vitamin B1 (thiamine) in your body. Your healthcare provider will do a blood test to check your vitamin B1 level before starting and during treatment with INREBIC.

    Your healthcare provider may tell you to stop taking INREBIC and take a B1 vitamin if you develop side effects during treatment with INREBIC.

    Call your healthcare provider right away if you develop diarrhea, nausea, or vomiting that does not respond to treatment.

     

    Get emergency medical help right away if you develop the following:

    Icon depicting confusion, memory problems, or drowsiness.

    Confusion, memory problems, or drowsiness

    Icon depicting problems with balance and movement, such as difficulty walking

    Problems with balance and movement, such as difficulty walking

    Icon depicting eye problems, such as double or blurred vision or abnormal eye movements.

    Eye problems, such as double or blurred vision or abnormal eye movements

     

    Call your healthcare provider if you experience rapid weight loss or weight loss that does not get better with treatment.

    INREBIC can cause serious side effects, including:

    Low blood cell counts

    INREBIC may cause low red blood cell counts (anemia) and low platelet counts (thrombocytopenia) in some people. You may need a blood transfusion if your blood counts drop too low. Your healthcare provider will do blood tests to check your blood counts before you start and during treatment with INREBIC. Tell your healthcare provider if you develop any bleeding or bruising during treatment with INREBIC.

     

    Nausea, vomiting, and diarrhea

    Your healthcare provider may give you certain medicines to help treat your nausea, vomiting, and diarrhea. Call your healthcare provider or get emergency medical help right away if you have nausea, vomiting, or diarrhea that does not get better with treatment.

     

    Liver problems

    Your healthcare provider will do blood tests to check your liver function before starting and during treatment with INREBIC.

     

    Amylase and lipase increases

    You may have changes in your blood amylase or lipase levels that may indicate a problem with your pancreas. Your healthcare provider will do blood tests to check your amylase or lipase levels before starting and during treatment with INREBIC.

     

    Increased risk of major cardiac events such as heart attack, stroke, or death in people
    who have cardiovascular risk factors and who are current or past smokers while using
    another JAK inhibitor to treat rheumatoid arthritis

    Get emergency help right away if you have any symptoms of a heart attack or stroke
    while taking INREBIC, including:

    • discomfort in the center of your chest that lasts for more than a few minutes, or that goes away and comes back
    • severe tightness, pain, pressure, or heaviness in your chest, throat, neck, or jaw
    • pain or discomfort in your arms, back, neck, jaw, or stomach
    • shortness of breath with or without chest discomfort
    • breaking out in a cold sweat
    • nausea or vomiting
    • feeling lightheaded
    • weakness in one part or on one side of your body
    • slurred speech

     

    Increased risk of blood clots

    Blood clots in the veins of your legs (deep vein thrombosis, DVT) or lungs (pulmonary
    embolism, PE) have happened in people taking another JAK inhibitor for rheumatoid
    arthritis and may be life-threatening.
    Tell your healthcare provider right away if you have any signs and symptoms of blood clots during treatment with INREBIC, including:

    • swelling, pain, or tenderness in one or both legs
    • sudden unexplained chest or upper back pain
    • shortness of breath or difficulty breathing

     

    Possible increased risk of new (secondary) cancers

    People who take another JAK inhibitor for rheumatoid arthritis have an increased risk of
    new (secondary) cancers, including lymphoma and other cancers. People who smoke or
    who smoked in the past have an added risk of new cancers.

    The most common side effects of INREBIC include:

    • Diarrhea
    • Nausea
    • Low red blood cell counts (anemia)
    • Vomiting

    These are not all the possible side effects of INREBIC. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

    Talk to your doctor or pharmacist about side effects, including gastrointestinal
    (GI) side effects. If you do have GI side effects such as nausea, vomiting and
    diarrhea, your doctor may:

    • Adjust or stop your dose
    • Tell you to take your dose with a high fat meal
    • Give you certain medicines to help treat your nausea, vomiting, and
      diarrhea

     
    Call your doctor or get emergency medical help right away if you have nausea,
    vomiting, or diarrhea that does not get better with treatment.

     

    Possible INREBIC side effects: Image of man and woman talking with a doctor.

    Get resources and support.

    Learn More

    Indication

    What is INREBIC® (fedratinib)?

    INREBIC is a prescription medicine used to treat adults with certain types of myelofibrosis (MF). It is not known if INREBIC is safe and effective in children.


    Important Safety Information

     

    WARNING: ENCEPHALOPATHY INCLUDING WERNICKE’S

    What is the most important information I should know about INREBIC?

    INREBIC may cause serious side effects, including:

    • Encephalopathy (including Wernicke’s encephalopathy). A serious and sometimes fatal neurological problem called encephalopathy (including Wernicke’s encephalopathy) has happened in some people who take INREBIC. Wernicke’s encephalopathy is a neurologic emergency that can happen if you do not have enough vitamin B1 (thiamine) in your body. Your healthcare provider will do a blood test to check your vitamin B1 level before starting and during treatment with INREBIC. Your healthcare provider may tell you to stop taking INREBIC and take a vitamin B1 supplement if you develop side effects during treatment with INREBIC.

     

    Call your healthcare provider right away if you develop diarrhea, nausea, or vomiting that does not respond to treatment.

    Get emergency medical help right away if you develop the following:

      • confusion, memory problems, or drowsiness
      • problems with balance and movement, such as difficulty walking
      • eye problems, such as double or blurred vision or abnormal eye movements

     

    Call your healthcare provider if you experience rapid weight loss or weight loss that does not get better with treatment.

     

    Before taking INREBIC, tell your healthcare provider about all your medical conditions, including if you:

    • have low red blood cell or platelet counts
    • have or have had liver problems
    • have or have had kidney problems
    • have had cancer in the past
    • are a current or past smoker
    • have had a blood clot, heart attack, other heart problems, or stroke
    • are breastfeeding or plan to breastfeed. It is not known if INREBIC passes into your breast milk. You should not breastfeed during treatment with INREBIC and for at least 1 month after your last dose. Talk to your healthcare provider about the best way to feed your baby during treatment with INREBIC.

     

    Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

     

    INREBIC and other medicines may affect each other causing unwanted side effects. Know the medicines you take. Keep a list of them to show your healthcare provider and pharmacist when you get a new medicine.

     

    How should I take INREBIC?

     

    What are the possible side effects of INREBIC?
    INREBIC can cause serious side effects, including:

     

    The most common side effects of INREBIC include:

     

    These are not all of the possible side effects of INREBIC.

     

    Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

     

    Please see full Prescribing Information for INREBIC including BOXED WARNING and Medication Guide.