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).
Leflunomide must not be used during pregnancy because it may cause serious harm (possibly death) to an unborn baby. Women of childbearing age must have a negative pregnancy test before starting this medication. They must also use reliable forms of birth control during treatment and after stopping it until they have finished taking another drug that helps leflunomide leave the body and confirmed through 2 blood tests that the leflunomide levels are very low (see How to Use section). If you become pregnant or think you may be pregnant, tell your doctor right away (see also Precautions section).
This drug may rarely cause serious (possibly fatal) liver disease. Most cases occur within 6 months of taking this drug. If you already have liver disease (such as hepatitis B or C), leflunomide should not be used. Liver function (blood) tests must be performed periodically while taking leflunomide. Tell your doctor right away if you notice nausea/vomiting that doesn't stop, dark urine, light-colored stools, stomach/abdominal pain, yellowing eyes/skin. See Drug Interactions section.
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.
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.
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