This medication is used to treat certain cancers (such as chronic lymphocytic leukemia/small lymphocytic lymphoma, Waldenstrom's macroglobulinemia). Ibrutinib belongs to a class of drugs known as kinase inhibitors. It works by slowing or stopping the growth of cancer cells.

Ibrutinib is also used to treat a certain problem that may occur after a stem cell transplant (chronic 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 ibrutinib and each time you get a refill. If you have any questions, ask your doctor or pharmacist.

Take this medication by mouth with a full glass of water (8 ounces or 240 milliliters) as directed by your doctor, usually once daily. Swallow the capsules and tablets whole. Do not open, break, or chew the capsules. Do not cut, crush, or chew the tablets. Drink plenty of fluids while taking ibrutinib unless otherwise directed by your doctor.

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

Do not increase your dose or take this medication more often than prescribed. Your condition will not improve any faster, and your risk of serious side effects will increase.

Avoid eating grapefruit or drinking grapefruit juice while using this medication unless your doctor or pharmacist says you may do so safely. Also avoid eating Seville oranges (often found in marmalade). Grapefruit and Seville oranges can increase the chance of side effects with this medicine. Ask your doctor or pharmacist for more details.

Since this drug can be absorbed through the skin and lungs and may harm an unborn baby, women who are pregnant or who may become pregnant should not handle this medication or breathe the dust from the capsules.

Upset stomach, diarrhea, nausea, vomiting, decreased appetite, headache, joint/muscle pain, numbness/tingling of arms/legs, constipation, dizziness, or tiredness may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

This medication may raise your blood pressure. Check your blood pressure regularly and tell your doctor if the results are high. Your doctor may control your blood pressure with medication.

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

• easy bruising/bleeding
• black/bloody stools
• vomit that looks like coffee grounds
• fast/irregular/pounding heartbeat
• unusual tiredness
• swelling ankles/feet
• signs of low red blood cell count (such as rapid breathing, pale skin, shortness of breath)

Ibrutinib sometimes causes side effects due to the rapid destruction of cancer cells (tumor lysis syndrome). To lower your risk, your doctor may add a medication and tell you to drink plenty of fluids. Tell your doctor right away if you have symptoms such as:

• low back/side pain (flank pain)
• signs of kidney problems (such as painful urination, pink/bloody urine, change in the amount of urine)
• muscle spasms/weakness

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).

This medication has rarely caused very serious (possibly fatal) liver disease. Tell your doctor right away if you develop symptoms of liver disease, such as nausea/vomiting that doesn't stop, loss of appetite, stomach/abdominal pain, yellowing eyes/skin, dark urine.

Very rarely, people taking this medication have developed other cancers (including skin cancer). Consult your doctor for more details.

Get medical help right away if you have any very serious side effects, including:

• chest pain
• signs of bleeding in the brain or a stroke (such as fainting, sudden vision changes, severe nausea, seizures, confusion, weakness on one side of the body, trouble speaking)

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 any 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.

Before taking ibrutinib, 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:

• blood/bleeding problems
• heart problems (such as fast/irregular heartbeat, previous heart attack)
• high blood pressure
• kidney problems
• liver problems
• high levels of uric acid in the blood

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).

Ibrutinib 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). 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 ibrutinib before having any immunizations/vaccinations. Avoid contact with people who have recently received live vaccines (such as flu vaccine inhaled through the nose).

To lower the chance of getting cut, bruised, or injured, use caution with sharp objects like razors and nail cutters, and avoid activities such as contact sports.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products). Your doctor may tell you to temporarily stop treatment with this medication before certain medical, surgical, or dental procedures.

Older adults may be at greater risk for low red blood cell count, bleeding, fast/irregular heartbeat, and high blood pressure while using this drug.

Since this drug can be absorbed through the skin and lungs and may harm an unborn baby, women who are pregnant or who may become pregnant should not handle this medication or breathe the dust from the capsules.

Tell your doctor if you are pregnant or plan to become pregnant. You should not become pregnant while using ibrutinib. Ibrutinib may harm an unborn baby. Your doctor should order a pregnancy test before you start this medication. Men and women using this medication should ask about reliable forms of birth control during treatment and for 1 month after the last dose. If you or your partner becomes pregnant, talk to your doctor right away about the risks and benefits of this medication.

It is unknown if this drug passes into breast milk. Because of the possible risk to the infant, breastfeeding is not recommended while using this drug and for 1 week after the last dose. Consult your doctor before breastfeeding.

See also How to Use section.

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 are:

• other drugs that can cause bleeding/bruising (such as antiplatelet drugs like clopidogrel, NSAIDs like ibuprofen/naproxen, "blood thinners" like warfarin/dabigatran)

Aspirin can increase the risk of bleeding when used with this medication. However, if your doctor has told you to take low-dose aspirin to prevent heart attack or stroke (usually 81-162 milligrams a day), you should keep taking the aspirin unless your doctor tells you not to. Ask your doctor or pharmacist for more details.

Other medications can affect the removal of ibrutinib from your body, which may affect how ibrutinib works. Examples include azole antifungals (such as itraconazole, ketoconazole), nefazodone, St. John's wort, HIV protease inhibitors (such as indinavir), macrolide antibiotics (such as erythromycin, clarithromycin), rifamycins (such as rifampin, rifabutin), ritonavir, certain drugs used to treat seizures (such as carbamazepine, phenytoin), among others.

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 count, kidney/liver/heart function, heart rate, uric acid) should be done while you are taking this medication. Keep all medical and lab appointments. Consult your doctor for more details.

If you miss a dose, take it as soon as you remember. If you don't remember until the next day, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

Store in the original container 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.

Your condition can cause complications in a medical emergency. For information about enrolling in MedicAlert, call 1-888-633-4298 (US) or 1-800-668-1507 (Canada).