This medication is used to treat certain bone marrow disorders (myelofibrosis, polycythemia vera). It works by blocking your body from producing substances called growth factors. Growth factors cause cells to grow and divide, and cause the blood cell and spleen problems found in these disorders. Ruxolitinib belongs to a class of drugs known as kinase inhibitors. Though not a cure for these disorders, ruxolitinib may help with some of the symptoms, including abdominal discomfort, pain under left ribs, early feelings of fullness from meals, night sweats, itching, and bone/muscle pain.

Ruxolitinib is also used to treat a certain problem that may occur after certain stem cell or bone marrow transplants (graft versus host disease). It works by weakening your body's defense system (immune system).

Read the Patient Information Leaflet if available from your pharmacist before you start taking ruxolitinib and each time you get a refill. If you have any questions, ask your doctor or pharmacist.

Take this medication by mouth with or without food as directed by your doctor, usually twice daily. If you are unable to swallow the tablets, ask your doctor about other ways to take this medication.

The dosage is based on your medical condition, lab tests, response to treatment, and other medications you may be taking. Be sure to tell your doctor and pharmacist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Avoid eating grapefruit or drinking grapefruit juice while using this medication unless your doctor or pharmacist says you may do so safely. Grapefruit can increase the chance of side effects with this medicine. Ask your doctor or pharmacist for more details.

To reduce your risk of side effects, your doctor may direct you to start this medication at a low dose and gradually increase your dose. Follow your doctor's instructions carefully. Do not increase your dose or use this drug more often or for longer than prescribed. Your condition will not improve any faster, and your risk of side effects will increase.

Use this medication regularly to get the most benefit from it. To help you remember, take it at the same times each day.

Do not stop taking ruxolitinib without consulting your doctor. Some conditions may become worse when this drug is suddenly stopped. Also, you may experience symptoms such as fever, trouble breathing, dizziness, and unusual bleeding/bruising. To prevent these symptoms while you are stopping treatment with this drug, your doctor may reduce your dose gradually. Consult your doctor or pharmacist for more details. Report any new or worsening symptoms right away.

Tell your doctor if your symptoms do not get better or if they get worse.

Dizziness, diarrhea, headache, weight gain, or gas may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

People using this medication may have serious side effects. However, you have been prescribed this drug because your doctor has judged that the benefit to you is greater than the risk of side effects. Careful monitoring by your doctor may decrease your risk.

Tell your doctor right away if you have any serious side effects, including:

• unusual tiredness
• easy bleeding/bruising
• unusual skin changes

This medication may lower your ability to fight infections. This may make you more likely to get a serious (rarely fatal) infection or make any infection you have worse. Tell your doctor right away if you have any signs of infection (such as sore throat that doesn't go away, fever, chills, cough, painful skin rash/blisters).

This medication may also increase your risk of getting a rare but very serious (sometimes fatal) brain infection (progressive multifocal leukoencephalopathy-PML). Get medical help right away if any of these rare but very serious side effects occur: clumsiness, loss of coordination, weakness, sudden change in your thinking (such as confusion, difficulty concentrating), difficulty moving your muscles, problems with speech, seizure, vision changes.

Another medication similar to ruxolitinib has caused serious (possibly fatal) side effects, including heart problems, blood clots, and cancer (such as lymphoma). Before using ruxolitinib, tell your doctor or pharmacist if you have a history of heart disease, stroke, cancer, or any risk factors for heart disease (such as high blood pressure, diabetes, previous blood clots, high cholesterol, smoking or history of smoking). Discuss the risks and benefits of treatment with your doctor. Get medical help right away if you have symptoms such as:

• shortness of breath/rapid breathing
• chest/jaw/left arm pain
• unusual sweating
• confusion
• sudden dizziness/fainting
• pain/swelling/warmth in the groin/calf
• sudden/severe headaches
• trouble speaking
• weakness on one side of the body
• sudden vision changes

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including:

• rash
• itching/swelling (especially of the face/tongue/throat)
• severe dizziness
• trouble breathing

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

See also Side Effects section.

Before taking ruxolitinib, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of:

• current/past/returning infections (such as herpes, tuberculosis)
• kidney disease
• liver disease
• cancer (such as skin cancer)

This drug may make you dizzy. Alcohol or marijuana (cannabis) can make you more dizzy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).

Ruxolitinib can make you more likely to get infections or may make current infections worse. Stay away from anyone who has an infection that may easily spread (such as chickenpox, COVID-19, measles, flu, tuberculosis). Talk to your doctor if you have been exposed to an infection or for more details.

Tell your health care professional that you are using ruxolitinib before having any immunizations/vaccinations. Avoid contact with people who have recently received live vaccines (such as flu vaccine inhaled through the nose).

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.

It is unknown if this medication passes into breast milk. Because of the possible risk to the infant, breastfeeding is not recommended while using this medication and for 2 weeks after the last dose. Consult your doctor before breastfeeding.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

Some products that may interact with this drug include:

• other drugs that weaken the immune system/increase the risk of infection (such as natalizumab, rituximab)

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call 1-800-222-1222. Canada residents can call 1-844-764-7669.

Do not share this medication with others.

Lab and/or medical tests (such as complete blood counts, cholesterol/triglyceride levels, skin exams) should be done before you start taking this medication and while you are taking it. Keep all medical and lab appointments. Consult your doctor for more details.

If you miss a dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.