Pentostatin is used to treat a certain type of cancer (hairy cell leukemia). It works by slowing or stopping the growth of cancer cells.

This section contains uses of this drug that are not listed in the approved professional labeling for the drug but that may be prescribed by your health care professional. Use this drug for a condition that is listed in this section only if it has been so prescribed by your health care professional.

This drug may also be used for other types of cancer (such as chronic lymphocytic leukemia).

This medication is given by injection into a vein by a health care professional as directed by your doctor, usually every other week. The dosage is based on your medical condition, body size, and response to treatment.

To help reduce side effects to the kidneys, your doctor may prescribe IV fluids before and after you receive pentostatin.

Mild rash/itching may occur. Tell your doctor or pharmacist promptly if any of these effects occur. Nausea, vomiting, diarrhea, loss of appetite, increased sweating, or mouth sores may also 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:

• signs of kidney problems (such as change in the amount of urine)
• dark urine
• yellowing eyes/skin
• severe stomach/abdominal pain
• dizziness
• drowsiness
• headache
• trouble sleeping
• shortness of breath
• cough
• unusual weakness/tiredness
• swelling ankles/feet
• muscle/joint pain
• muscle spasm
• mental/mood changes (such as depression, anxiety)
• numbness/tingling of the skin
• decreased sexual ability/interest
• fainting
• fast/slow/irregular heartbeat
• vision/hearing changes
• pain/redness/swelling of arms or legs

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

• seizures
• chest pain

This medication may cause very serious blood disorders (decreased bone marrow function leading to low number of blood cells such as red cells, white cells, and platelets). This effect can cause anemia, decrease your body's ability to fight an infection, or cause your body to bruise or bleed more easily. Tell your doctor right away if you develop any of the following symptoms: signs of infection (such as sore throat that doesn't go away, fever), easy bruising/bleeding, unusual tiredness, fast/pounding heartbeat.

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.

Before using pentostatin, 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:

• kidney disease
• liver disease
• recent/current infections
• blood/bone marrow disorder

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

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

Pentostatin 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.

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

Tell your doctor if you are pregnant or plan to become pregnant. You should not become pregnant while using pentostatin. Pentostatin may harm an unborn baby. Ask about reliable forms of birth control while using this medication. If you become 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. 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:

• fludarabine
• vidarabine

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. Symptoms of overdose may include: trouble breathing, seizures, fainting, change in the amount of urine, severe stomach/abdominal pain.

Lab and/or medical tests (such as blood count, kidney/liver function) should be done while you are using this medication. Keep all medical and lab appointments. Consult your doctor for more details.

It is important to get each dose of this medication as scheduled. If you miss a dose, ask your doctor or pharmacist right away for a new dosing schedule.

Not applicable. This medication is given in a clinic and will not be stored at home.

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).