This medication is used to treat rheumatoid arthritis, a condition in which the body's defense system (immune system) fails to recognize the body as itself and attacks the healthy tissues around the joints. Leflunomide helps to reduce the joint damage/pain/swelling and helps you to move better. It works by weakening your immune system and decreasing swelling (inflammation).

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 psoriatic arthritis. It may also be used to reduce the risk of rejection of organ transplant.

Take this medication by mouth with or without food as directed by your doctor, usually once daily. Take this medication exactly as prescribed. You may be instructed to take a higher dose for the first 3 days of treatment.

The dosage is based on your medical condition and response to treatment.

Take this medication regularly in order to get the most benefit from it. To help you remember, take it at the same time each day.

After treatment is stopped, a different drug (cholestyramine) may be given as directed to help remove leflunomide from your body. This procedure is used if you need a rapid removal of the drug from your system (for example, if you are a female/male planning to have children, or suffering from severe side effects). Without the procedure, the drug may stay in your body for up to 2 years. Consult your doctor or pharmacist for more details.

Tell your doctor if your symptoms last or get worse.

Diarrhea, nausea, and dizziness may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor right away if you have any serious side effects, including:

• cough
• numbness/tingling of hands/feet
• hair loss
• chest pain
• fast/pounding heartbeat
• increased thirst/urination
• muscle cramp/pain
• mental/mood changes
• vision changes
• easy bruising/bleeding
• unusual growths/lumps
• unexplained weight loss
• unusual tiredness

This medication may raise your blood pressure. Check your blood pressure regularly and tell your doctor if the results are high.

This medication may lower your ability to fight infections. This may make you more likely to get a serious (rarely fatal) infection or make any infection you have worse. Get medical help right away if you have any signs of infection (such as sore throat that doesn't go away, fever, swollen lymph nodes, chills).

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

• skin sores

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

Leflunomide can commonly cause a mild rash that is usually not serious. However, you may not be able to tell it apart from a rare rash that could be a sign of a severe allergic reaction. Get medical help right away if you develop any rash.

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 leflunomide, tell your doctor or pharmacist if you are allergic to it; or to teriflunomide; 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:

• immune system disorder (such as HIV infection)
• current/recent infection (such as tuberculosis)
• cancer
• bone marrow/blood disorder
• kidney disease
• liver disease (such as hepatitis B or C)
• alcohol abuse
• heart disease (such as heart failure)
• high blood pressure
• lung disease

This drug may make you dizzy. Alcohol or marijuana (cannabis) can make you more dizzy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Avoid alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis). Alcohol may also cause liver disease.

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.

Leflunomide 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.

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

This medication must not be used during pregnancy. It may harm an unborn baby. Women of childbearing age must have a negative pregnancy test before starting this medication. Women using this medication should ask about reliable forms of birth control during treatment and for some time after the last dose. Men using this medication and their female partners should ask about reliable forms of birth control during treatment. If you or your partner becomes pregnant or may be pregnant, tell your doctor right away. (See also Warning section.)

It is not known whether this medication affects the sperm. To minimize any possible risk, the manufacturer recommends that men wishing to father a child should stop the medication and use another drug (cholestyramine) as directed to help this drug leave the body before attempting to father a child. (See How to Use section.) Consult your doctor for more details.

This drug may pass into breast milk and could have undesirable effects on a nursing infant. Breastfeeding is not recommended while using this drug. Consult your doctor before breastfeeding.

See also How to Use Section.

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:

• cholestyramine
• warfarin
• drugs affecting the liver (such as methotrexate)
• other drugs that weaken the immune system (such as cyclosporine, tacrolimus)

This medication can slow down the removal of other medications from your body, which may affect how they work. Examples of affected drugs include ketorolac, tovorafenib, among others.

This medication can speed up the removal of other medications from your body, which may affect how they work. Examples of affected drugs include vorasidenib, among others.

Because teriflunomide (used to treat multiple sclerosis) is very similar to this medication, do not take it while you are taking leflunomide.

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.

Do not share this medication with others.

A skin test to check for tuberculosis should be done before you start this medication. Lab and/or medical tests (such as liver function, blood counts, blood pressure) should be done while you are taking this medication. Keep all medical and lab appointments. Consult your doctor for more details.

If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

Store 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).