Leflunomide: Uses, Side Effects

Leflunomide affects the immune system and reduces swelling and inflammation in the body.

Leflunomide is used to treat the symptoms of rheumatoid arthritis.

Leflunomide may also be used for purposes not listed in this medication guide.

Important Information

Do not use leflunomide if you are pregnant and stop taking leflunomide if you think you might be pregnant. Use birth control to prevent pregnancy while you are taking leflunomide, and until you complete a “drug elimination” procedure.

Leflunomide can cause severe or fatal liver damage. Tell your doctor if you have a history of liver disease or if you also use other medicines such as: pain or arthritis medicine (including aspirin, Tylenol, and Advil/Motrin), medicines to treat tuberculosis or other infections, seizure medication, hormonal birth control or hormone replacement therapy, chemotherapy, cholesterol-lowering medicine, heart medication, or blood pressure medicine.

Your liver function will need to be tested often, and you may need to stop taking leflunomide based on the results of these tests.

Before taking this medicine

You should not use this medicine if you are allergic to leflunomide or teriflunomide, or if:

  • you are pregnant (you will need to have a negative pregnancy test before starting this treatment);
  • you have severe liver disease; or
  • you are also using teriflunomide.

Do not use leflunomide if you are pregnant or may become pregnant. Avoid getting pregnant until after you stop taking leflunomide and undergo a “drug elimination” procedure to help rid your body of this medicine. Stop taking leflunomide and call your doctor right away if you miss a period or think you might be pregnant.

To make sure leflunomide is safe for you, tell your doctor if you have:

  • a history of liver disease or hepatitis (leflunomide can cause severe liver problems);
  • a severe or uncontrolled infection;
  • kidney disease;
  • nerve problems, such as neuropathy caused by diabetes;
  • a history of tuberculosis;
  • a weak immune system or bone marrow disorder; or
  • if you are using any drugs that weaken your immune system (such as cancer medicine or steroids).

Use birth control to prevent pregnancy while you are taking this medicine. After you stop taking leflunomide, continue using birth control until you have received blood tests to make sure the drug has been eliminated from your body.

Ask your doctor if you should use a barrier form of birth control (condom or diaphragm with spermicide). Using hormonal contraception (birth control pills, injections, implants, skin patches, and vaginal rings) may increase your risk of liver damage while taking leflunomide.

It is not known whether leflunomide passes into breast milk or if it could harm a nursing baby. You should not breast-feed while using this medicine.

Side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • signs of infection–sudden weakness or ill feeling, fever, chills, sore throat, mouth sores, red or swollen gums, trouble swallowing;
  • sudden chest pain or discomfort, wheezing, dry cough, feeling short of breath;
  • easy bruising, unusual bleeding (nose, mouth, vagina, or rectum), purple or red pinpoint spots under your skin;
  • numbness, tingling, or burning pain in your hands or feet;
  • liver problems–nausea, upper stomach pain, itching, tiredness, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes); or
  • severe skin reaction–fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain, followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.

Common side effects may include:

  • nausea, diarrhea, stomach pain;
  • headache;
  • abnormal liver function tests;
  • thinning hair;
  • back pain;
  • weakness;
  • rash; or
  • high blood pressure.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.

What other drugs will affect leflunomide?

Leflunomide can cause severe or fatal liver damage. This effect is increased when you also use certain other medicines, including:

  • acetaminophen (Tylenol), aspirin, gout or arthritis medication (including gold injections); an NSAID (non-steroidal anti-inflammatory drug) –ibuprofen (Advil, Motrin), naproxen (Aleve), celecoxib, diclofenac, indomethacin, meloxicam, and others;
  • an antibiotic, antifungal medicine, or sulfa drug; tuberculosis medicine; antiviral or HIV/AIDS medication; medicine to treat mental illness; seizure medication–carbamazepine, phenytoin, valproic acid, and others;
  • birth control pills or hormone replacement therapy; anabolic steroids–methyltestosterone, “performance-enhancing drugs”; cancer medication; or
  • cholesterol-lowering medication–Crestor, Lipitor, Vytorin, Zocor, and others; heart or blood pressure medication.

This list is not complete, and many other drugs can interact with leflunomide. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Give a list of all your medicines to any healthcare provider who treats you. Not all possible interactions are listed in this medication guide.


Keyword: leflunomide.

* The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.