Leflunomide treats rheumatoid arthritis. May increase your risk of developing an infection. Notify your doctor if you notice any signs/symptoms of an infection.

Leflunomide Overview

Reviewed: September 28, 2013

Leflunomide is a prescription medication used to treat rheumatoid arthritis. This medication belongs to a group of drugs called DMARDs (disease modifying antirheumatic drugs) which work by suppressing the excessive activity of the immune system.

Leflunomide comes in tablet form. It is usually taken once daily, with or without food. 

Common side effects include diarrhea, nausea, vomiting, and headache.

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Leflunomide Cautionary Labels


Uses of Leflunomide

Leflunomide is a prescription medication used to treat rheumatoid arthritis.

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

Leflunomide Brand Names

Leflunomide may be found in some form under the following brand names:

Leflunomide Drug Class

Leflunomide is part of the drug class:

Side Effects of Leflunomide

Common side effects include:

  • diarrhea
  • vomiting
  • heartburn
  • headache
  • dizziness
  • weight loss
  • back pain
  • muscle pain or weakness
  • pain, burning, numbness, or tingling in the hands or feet
  • hair loss
  • mouth sores

Tell your doctor if you have any side effect that bothers you or does not go away.

These are not all the possible side effects of leflunomide. For more information, ask your doctor or pharmacist.

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Leflunomide Interactions

Tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements. Especially tell your doctor if you take:

  • acetaminophen (Tylenol)
  • anticoagulants ('blood thinners') such as warfarin (Coumadin, Jantoven)
  • aspirin and other nonsteroidal anti-inflammatory medications (NSAIDs such as ibuprofen [Advil, Motrin] and naproxen [Aleve, Naprosyn]
  • cholesterol-lowering medications (statins)
  • cholestyramine (Prevalite, Questran)
  • colestipol (Colestid)
  • etanercept (Enbrel)
  • gold compounds such as auranofin (Ridaura) and aurothioglucose (Aurolate, Solganol)
  • hydroxychloroquine
  • iron products
  • isoniazid (INH, Nydrazid, in Rifamate)
  • medications to treat cancer
  • methotrexate (Rheumatrex, Trexall)
  • niacin (nicotinic acid)
  • other medications that suppress the immune system such as azathioprine (Imuran), cyclosporine (Neoral, Sandimmune), sirolimus (Rapamune), and tacrolimus (Prograf)
  • rifampin (Rifadin, Rimactane, in Rifamate, in Rifater)

 This is not a complete list of leflunomide drug interactions. Ask your doctor or pharmacist for more information.

Leflunomide Precautions

Serious side effects have been reported.
  • Taking leflunomide may increase your risk of developing an infection. If you experience any of the following symptoms during your treatment with leflunomide, call your doctor: fever; sore throat; cough; flu-like symptoms; area of warm, red, swollen, or painful skin; painful, difficult, or frequent urination; or other signs of infection. Your treatment with leflunomide may need to be interrupted if you have an infection.
  • If you are already infected with tuberculosis (TB) leflunomide may make your infection more serious and cause you to develop symptoms, if you don't already have any. If you do have TB, your doctor will treat this infection with antibiotics before you begin taking leflunomide.
  • Do not have any vaccinations without talking to your doctor.
  • Severe liver damage, including fatal liver failure, has been reported in some patients treated with leflunomide. Tell your doctor if you experience any signs of liver problems, including:
    • extreme tiredness
    • stomach pain
    • yellowing of the whites of the eyes or skin (jaundice)
  • Leflunomide may cause high blood pressure. You should have your blood pressure checked before starting treatment and regularly while you are taking this medication.
  • Leflunomide may cause low blood cell counts and anemia.
  • Rare cases of severe skin reactions have been reported. Tell your doctor if you experience a skin rash during your treatment.
  • Ask your doctor about the safe use of alcoholic beverages while you are taking leflunomide.

Do not take leflunomide if you:

  • are allergic to leflunomide or any of its ingredients
  • are pregnant
  • have liver disease

Leflunomide Food Interactions

Medications can interact with certain foods. In some cases, this may be harmful and your doctor may advise you to avoid certain foods. In the case of leflunomide, there are no specific foods that you must exclude from your diet when receiving this medication.


Inform MD

Before receiving this medication tell your doctor about all of your medical conditions including if you:

  • have an infection now or if you have any signs of infection such as fever, cough, or flu-like symptoms
  • have a weakened immune system
  • have liver or kidney disease
  • have high blood pressure
  • have anemia
  • have cancer
  • are pregnant or plan to become pregnant
  • are breastfeeding or plan to breastfeed
  • drink large amounts of alcohol

Tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements.


Leflunomide and Pregnancy

Tell your doctor if you are pregnant or plan to become pregnant.

The FDA categorizes medications based on safety for use during pregnancy. Five categories - A, B, C, D, and X, are used to classify the possible risks to an unborn baby when a medication is taken during pregnancy.

Leflunomide falls into category X. 

Do not take leflunomide if you are pregnant or plan to become pregnant. Leflunomide may harm the fetus. You should not begin taking leflunomide until you have taken a pregnancy test with negative results and your doctor tells you that you are not pregnant. You must use an effective method of birth control before you begin taking leflunomide, during your treatment with leflunomide, and for 2 years after treatment. If your period is late or you miss a period during treatment with leflunomide, call your doctor immediately. Talk to your doctor if you plan to become pregnant within 2 years after stopping treatment with leflunomide. Your doctor can prescribe a treatment that will help to remove this medication more quickly from your body.

See FDA Warning.

Leflunomide and Lactation

Leflunomide should not be used by nursing mothers. It is not known whether leflunomide is excreted in human milk. Many drugs are excreted in human milk, and there is a potential for serious adverse reactions in nursing infants from leflunomide. Therefore, a decision should be made whether to proceed with nursing or to initiate treatment with leflunomide, taking into account the importance of the drug to the mother.

Leflunomide Usage

  • Take leflunomide exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.
  • Leflunomide comes in tablet form.
  • It is usually taken once daily.
  • For the first 3 days of treatment, your doctor may tell you to take a larger dose of leflunomide.


Leflunomide Dosage

Take this medication exactly as prescribed by your doctor. Follow the directions on your prescription label carefully.

The dose your doctor recommends may be based on the following:

The recommended dose of leflunomide is 100 mg tablet per day for 3 days.

The recommended dose of leflunomide is 20 mg/day, thereafter.

If dosing at 20 mg/day is not well tolerated, your doctor may decrease your dose to 10 mg/day.

Leflunomide Overdose

If you take too much leflunomide call your local Poison Control center or seek emergency medical attention right away.

Other Requirements

  • Store at room temperature between 15–30°C (59–86°F).
  • Keep this and all medications out of the reach of children.

Leflunomide FDA Warning



Pregnancy must be excluded before the start of treatment with leflunomide. Leflunomide is contraindicated in pregnant women, or women of childbearing potential who are not using reliable contraception. Pregnancy must be avoided during leflunomide treatment or prior to the completion of the drug elimination procedure after leflunomide treatment.


Severe liver injury, including fatal liver failure, has been reported in some patients treated with leflunomide. Patients with pre-existing acute or chronic liver disease, or those with serum alanine aminotransferase (ALT) >2×ULN before initiating treatment, should not be treated with leflunomide. Use caution when leflunomide is given with other potentially hepatotoxic drugs.

Monitoring of ALT levels is recommended at least monthly for six months after starting leflunomide, and thereafter every 6-8 weeks. If ALT elevation > 3 fold ULN occurs, interrupt leflunomide therapy while investigating the probable cause of the ALT elevation by close observation and additional tests. If likely leflunomide-induced, start cholestyramine washout and monitor liver tests weekly until normalized. If leflunomide-induced liver injury is unlikely because some other probable cause has been found, resumption of leflunomide therapy may be considered.