• If you are allergic to any anything, including medicines, dyes, additives, or foods. If you have ever reacted to a drug made with mouse proteins, you may be more likely to react to rituximab.

• If you have any medical conditions such as kidney disease, liver disease (including hepatitis), heart disease, congestive heart failure, diabetes, gout, or infections. These conditions may require that your medicine dose, regimen, or timing be changed.

• If you are pregnant, trying to get pregnant, or if there is any chance of pregnancy. It is not known if this drug might cause problems if either the male or female is taking it at the time of conception or during pregnancy. Men and women who are taking this drug should use some kind of birth control during treatment and for 12 months afterward. Check with your doctor about what kinds of birth control can be used with this medicine. This drug should be used during pregnancy only if the potential benefit is thought to justify the potential risk to the fetus.

• If you are breast-feeding. While no studies have been done, this drug may pass into breast milk and affect the baby.

• If you think you might want to have children in the future. It is not known whether or not this drug can affect fertility. Talk with your doctor about the possible risk with this drug and the options that may preserve your ability to have children.

• About any other prescription or over-the-counter medicines you are taking, including vitamins and herbs. In fact, keeping a written list of each of these medicines (including the doses of each and when you take them) with you in case of emergency may help prevent complications if you get sick.

Since rituximab may cause the blood pressure to drop, some doctors will ask that you not take blood pressure medicines the day you are due for your treatment.

Any drugs or supplements that interfere with blood clotting can raise the risk of bleeding during treatment with rituximab. These include:

• vitamin E
• non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin, ibuprofen (Advil, Motrin), naproxen (Aleve, Naprosyn), and many others
• warfarin (Coumadin)
• ticlopidine (Ticlid)
• clopidogrel (Plavix)

Note that many cold, flu, fever, and headache remedies contain aspirin or ibuprofen. Ask your pharmacist if you aren't sure what is in the medicines you take.

Studies of drug interactions have not been completed. Check with your doctor, nurse, or pharmacist about your other medicines, herbs, and supplements, and whether alcohol can cause problems with this medicine.

This drug can cause the rapid killing of tumor cells, which in some cases has led to serious kidney damage within the first 24 hours of treatment (a condition known as tumor lysis syndrome). This is more likely if you have a very large number of cancer cells in the body. If your doctor feels you might be at risk, he or she will give you medicines and/or fluids to help prevent this.

While taking this medicine, and for a few days afterward, there is a slight chance of a serious skin reaction. Symptoms often start as a skin rash with redness, peeling, blisters, or sores. You can also get redness and sores in the mouth, nose, or eyes, along with fever and body aches. If this starts to happen, call your doctor right away.

Your doctor will likely test your blood throughout your treatment, looking for possible effects of the drug on blood counts (described below) or on other body organs. Based on the test results, you may be given medicines to help treat any effects. Your doctor may also need to reduce or delay your next dose of this drug, or even stop it completely.

This drug can lower your white blood cell count, especially in the weeks after the drug is given. This can increase your chance of getting an infection. Be sure to let your doctor or nurse know right away if you have any signs of infection, such as fever (100.5° or higher), chills, pain when passing urine, new onset of cough, or bringing up sputum.

This drug may lower your platelet count in the weeks after it is given, which can increase your risk of bleeding. Speak with your doctor before taking any drugs or supplements that might affect your body’s ability to stop bleeding, such as aspirin or aspirin-containing medicines, warfarin (Coumadin), or vitamin E. Tell your doctor right away if you have unusual bruising, or bleeding such as nosebleeds, vomit that looks like coffee grounds, bleeding gums when you brush your teeth, or black, tarry stools.

This drug may lower your red blood cell count. If this occurs, it is usually a few weeks after starting treatment. A low red blood cell count (known as anemia) can cause shortness of breath, or make you to feel weak or tired all the time. Your doctor may give you medicines to help prevent or treat this condition, or you may need to get blood transfusions.

Do not get any immunizations (vaccines), either during or after treatment with this drug, without your doctor's OK. Rituximab may affect your immune system. This could make vaccinations ineffective, or even lead to serious infections if you get live vaccines during treatment or for some time afterward. Try to avoid contact with people who have recently received a live virus vaccine, such as the oral polio vaccine or smallpox vaccine. Check with your doctor about this.

If you are planning surgery, tell the doctor or dentist that you are taking this drug.

• mild allergic reaction with first infusion (may include fever, headache, chills, itching, hives, nausea, shortness of breath)*

• allergic reaction with second and later infusions (same symptoms as above)
• low white blood cell count with increased risk of infection*
• cough
• rash, itching
• nausea
• vomiting
• diarrhea
• muscle aches
• runny nose
• sinus infection

• serious allergic reaction, with hives, trouble breathing, tightness in the chest or throat, heart attack, or shock*
• serious skin reaction*
• kidney damage*
• low platelet count with increased risk of bleeding*
• blockage or hole in the bowel, with abdominal (belly) pain
• low red blood cell count (anemia) with tiredness and weakness*
• death due to allergic reaction, infection, lung damage, tumor lysis syndrome, serious skin rash, bowel obstruction, and other causes

*See the "Precautions" section for more detailed information.