Cladribine is used to treat relapsing forms of multiple sclerosis (MS). It is not a cure for MS but it is thought to help by preventing immune system cells (lymphocytes) from attacking the nerves in your brain and spinal cord. It may help to slow disease worsening and decrease flare-ups of symptoms.

Read the Medication Guide provided by your pharmacist before you start taking cladribine and each time you get a refill. If you have any questions, ask your doctor or pharmacist.

Take this medication by mouth with or without food as directed by your doctor. The dosage is based on your medical condition, weight, and response to treatment. You should usually only take this medication for 2 treatment weeks (with about a month separating each treatment week) each year for 2 years. After completing the 2-year treatment course, do not take cladribine during the next 2 years. Follow your doctor's instructions carefully.

Wash and dry your hands before handling this medication. Swallow the tablet(s) whole. Do not crush or chew the tablets. After taking the medication, wash your hands with soap and water.

Take this medication at least 3 hours before or after taking other medications.

If the tablet breaks, avoid inhaling the powder or dust, and avoid direct contact with the skin or eyes. If contact occurs, wash the affected skin well with soap and water or rinse your eyes with plain water. Consult your pharmacist for 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 tablets.

See also Warning section.

Nausea, headache, back pain, or stomach/abdominal pain may 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 liver problems (such as nausea/vomiting that doesn't stop, loss of appetite, severe stomach/abdominal pain, yellowing eyes/skin, dark urine)

This medication decreases bone marrow function, an effect that may lead to a 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 easy bruising/bleeding. Tell your doctor right away if you develop any of the following symptoms:

• unusual tiredness
• pale skin
• signs of infection (such as sore throat that doesn't go away, fever, chills, painful rash/sores, frequent/painful urination)
• easy bruising/bleeding

This medication may increase your risk of getting a rare but very serious (possibly fatal) brain infection (progressive multifocal leukoencephalopathy-PML). Get medical help right away if you have any of these side effects:

• clumsiness
• loss of coordination/balance
• weakness
• sudden change in your thinking (such as confusion, difficulty concentrating, memory loss)
• difficulty talking/walking
• seizure
• vision changes

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

• shortness of breath
• fast/irregular heartbeat
• swelling of the ankles/feet

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 taking cladribine, 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 (such as hepatitis B or C)
• nerve/muscle disorder
• blood/bone marrow disorder
• current/recent/returning infections (such as tuberculosis, herpes, shingles, HIV)
• cancer
• heart failure

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

Tell your doctor that you are taking cladribine before getting a blood transfusion.

Cladribine 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 cladribine 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.

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 tablets.

This medication must not be used during pregnancy. It may harm an unborn baby. It is important to prevent pregnancy while taking this medication and for at least 6 months after each treatment course. If you or your partner become pregnant or think you may be pregnant, tell your doctor right away. See also Warning section.

It is unknown if this drug passes into breast milk. Because of the possible risk to the infant, breastfeeding is not recommended while taking this drug and for 10 days after the last dose. 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 are:

• other drugs that weaken the immune system/increase the risk of infection (such as cyclosporine, natalizumab, rituximab, drugs to treat cancer like irinotecan)

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.

Lab and/or medical tests (such as complete blood count, TB test, HIV test, hepatitis B and C screening, liver function, MRI of the brain, cancer screening) should be done before you start taking this medication and while you are taking it. 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, take it as soon as you remember on the same day. If you miss a day, take the missed dose the next day and extend the treatment week. Do not take more than 1 dose each day. Do not double the dose to catch up.

Store in the original package 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).