SIDE EFFECTS: See also Warning section. Nausea, vomiting, diarrhea, headache, muscle aches, tiredness, loss of appetite, and pain/redness at the injection site may occur. Nausea and vomiting can be severe. In some cases, your doctor may prescribe medication to prevent or relieve nausea and vomiting. Eating several small meals, not eating before treatment, or limiting activity may help lessen some of these effects. If these effects persist or worsen, tell your doctor or pharmacist promptly. Many people using this medication may have serious side effects. However, your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. To lower your risk of serious side effects, your doctor will follow your condition closely and order lab tests. Pain or sores in the mouth and throat may occur. Brush your teeth gently/carefully, avoid using mouthwash that contains alcohol, and rinse your mouth frequently with cool water mixed with baking soda or salt. It may also be best to eat soft, moist foods. Tell your doctor right away if you have any serious side effects, including: fast/irregular heartbeat, swelling ankles/feet. This medication affects your blood cells, reducing your ability to fight infections. Although fever and chills are common side effects of fludarabine, they may also be signs of an infection. Tell your doctor if you develop chills or fever. Fludarabine 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. Get medical help right away if any of these rare but very serious side effects occur: bloody/black/tarry stool, persistent cough, coughing up blood, painful/difficult breathing, chest pain, seizures. A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any of the following symptoms of a serious allergic reaction: 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.

PRECAUTIONS: Before using fludarabine, 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. Tell your doctor your medical history, especially of: current infections, certain virus illnesses (herpes, chickenpox), blood disorders (e.g., anemia, clotting problems), kidney problems. Do not have immunizations/vaccinations without the consent of your doctor, and avoid contact with people who have recently received oral polio vaccine or flu vaccine inhaled through the nose. Wash your hands well to prevent the spread of infections. Avoid contact with people who have illnesses that may spread to others (e.g., flu, chickenpox). To lower your chance of getting cut, bruised, or injured, use caution with sharp objects like razors and nail cutters, and avoid activities such as contact sports. Kidney function declines as you grow older. This medication is removed by the kidneys. Therefore, elderly people may be at greater risk for side effects (e.g., infection, bleeding) while using this drug. This drug is not recommended for use during pregnancy. It may harm the unborn baby. If you become pregnant or think you may be pregnant, tell your doctor right away. To avoid pregnancy, both males and females using this drug should use reliable form(s) of birth control (e.g., birth control pills, condoms) during treatment and for 6 months after treatment has ended. Consult your doctor for details and to discuss effective forms of birth control. It is not known whether this medication passes into breast milk. However, it may have undesirable effects on a nursing infant. Therefore, breast-feeding while using this medication is not recommended. Consult your doctor before breast-feeding.

DRUG INTERACTIONS: 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: "blood thinners" (e.g., warfarin, enoxaparin), live vaccines (e.g., flu vaccine inhaled through the nose, typhoid/polio vaccine taken by mouth), pentostatin, other drugs that weaken the immune system/increase the risk of infection (such as natalizumab, rituximab), salicylates/NSAIDs (e.g., aspirin, ibuprofen, naproxen). Check all prescription and nonprescription medicine labels carefully since many contain pain relievers/fever reducers (NSAIDs such as ibuprofen, naproxen, and aspirin) that can increase your risk of bleeding. Low-dose aspirin should be continued if prescribed by your doctor for heart attack or stroke prevention (usually at dosages of 81-325 milligrams a day). Consult your doctor or pharmacist for more details.

OVERDOSE: 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 their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center.