Cladribine is used to treat hairy cell leukemia (cancer of a certain type of white blood cell). Cladribine is in a class of medications known as purine analogs. It works by stopping or slowing the growth of cancer cells.

Cladribine injection must be given in a hospital or medical facility under the supervision of a doctor who is experienced in giving chemotherapy medications for cancer.

Cladribine may cause a severe decrease in the number of all types of blood cells in your blood. This may cause certain symptoms and may increase the risk that you will develop a serious infection or bleeding. If you experience any of the following symptoms, call your doctor immediately: fever, sore throat, chills, or other signs of infection; unusual bleeding or bruising; black and tarry stools; red blood in stools; bloody vomit; or vomited material that looks like coffee grounds.

Cladribine may cause severe nerve damage. Nerve damage may occur more than one month after cladribine injection is given. If you experience any of the following symptoms, call your doctor immediately: pain, burning, numbness, or tingling in the hands or feet; weakness in the arms or legs; or loss of ability to move your arms or legs.

Cladribine may cause serious kidney problems. Tell your doctor if you have or have ever had kidney disease. Tell your doctor and pharmacist if you are taking aminoglycoside antibiotics such as amikacin (Amikin), gentamicin (Garamycin), or tobramycin (Tobi, Nebcin); amphotericin B (Amphotec, Fungizone); angiotensin-converting enzyme (ACE) inhibitors such as benazepril (Lotensin), captopril (Capoten), enalapril (Vasotec), fosinopril (Monopril), lisinopril (Prinivil, Zestril), moexipril (Univasc), perindopril (Aceon), quinapril (Accupril), ramipril (Altace), and trandolapril (Mavik); or nonsteroidal anti-inflammatory medications such as diclofenac (Cataflam, Voltaren), naproxen (Aleve, Naprosyn), and sulindac (Clinoril). If you experience any of the following symptoms, call your doctor immediately: decreased urination; swelling of the face, arms, hands, feet, ankles, or lower legs; or unusual tiredness or weakness.

Keep all appointments with your doctor and the laboratory. Your doctor will order certain tests before, during, and after treatment to check your body's response to cladribine.

Cladribine injection comes as a solution (liquid) to be injected intravenously (into a vein) by a doctor or nurse in a medical facility. It is usually given slowly over 7 days as a continuous intravenous injection.

Before receiving cladribine,

• tell your doctor and pharmacist if you are allergic to cladribine, any other medications, or any of the ingredients in cladribine injection. Ask your pharmacist for a list of the ingredients.
• tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention the medications listed in the IMPORTANT WARNING section and any of the following: immunosuppressants such as azathioprine (Imuran), cyclosporine (Neoral, Sandimmune), methotrexate (Rheumatrex), sirolimus (Rapamune), and tacrolimus (Prograf). Your doctor will need to monitor you carefully for side effects. Many other medications may also interact with cladribine, so be sure to tell your doctor about all the medications you are taking, even those that do not appear on this list.
• tell your doctor if you have or have ever had liver disease.
• tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. You should not become pregnant while you are receiving cladribine. If you become pregnant while receiving cladribine, call your doctor. Cladribine may harm the fetus.

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.

Symptoms of overdose may include the following:

• decreased urination
• swelling of the face, arms, hands, feet, ankles, or lower legs
• unusual tiredness or weakness
• unusual bleeding or bruising
• black and tarry or bloody stools
• bloody vomit or vomited material that looks like coffee grounds
• fever, sore throat, chills, or other signs of infection
• pain, burning, numbness, or tingling in the hands or feet
• weakness in the arms or legs.
• loss of ability to move the arms or legs.

Unless your doctor tells you otherwise, continue your normal diet.

Cladribine may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• nausea
• vomiting
• diarrhea
• stomach pain
• constipation
• loss of appetite
• skin rash
• headache
• excessive sweating
• pain, redness, swelling, or sores in the place where the medication was injected

Some side effects can be serious. If you experience any of these symptoms or those listed in the IMPORTANT WARNING section, call your doctor immediately:

• pale skin
• excessive tiredness
• shortness of breath
• dizziness
• fast heartbeat

Cladribine may cause other side effects. Call your doctor if you have any unusual problems while using this medication.

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.