Leflunomide (LEF)

Drug Name
Leflunomide (LEF)

Brand Name(s)
Arava®, generics

Drug Class
Disease-Modifying Anti-Rheumatic Drug (DMARD)

LEF is a DMARD used to treat inflammatory types of arthritis, such as rheumatoid and psoriatic arthritis.

  • What types of arthritis is LEF used for?

    LEF is a DMARD used to treat inflammatory types of arthritis, such as rheumatoid and psoriatic arthritis.

    LEF is commonly used as an alternative to methotrexate (MTX) for people who do not adequately respond to MTX or are intolerant to MTX. LEF may also be used in combination with MTX or as an alternative to MTX in combination therapy.

  • How is LEF administered?

    LEF is taken orally in pill form.

  • What is the typical dose and when do I take it?

    LEF is usually taken as a 10 mg or 20 mg tablet once a day. In some cases, it may be prescribed every other day.

  • How long will it take to work?

    Like with many DMARDs, you will not feel the effects of LEF right away. Most people start noticing the effects about six to eight weeks after they start to take the medication, but its full benefit may not be apparent for up to three months. It is important to be patient and continue taking your medication.

    To provide symptom relief while you are waiting for LEF to work, your prescriber may recommend you take a steroid (such as prednisone) or a non-steroidal anti-inflammatory drug (NSAID).

  • When should I not take LEF and call my doctor?

    You may not be able to take LEF if you have any blood disorders (e.g., anemia, low platelets), an active infection, severe kidney or liver disorders, problems with your immune system or if you suffer from alcoholism or alcoholic liver disease. If you have any of these conditions, please discuss the situation with your prescriber. (LEF has the potential to harm your liver so your alcohol use must be restricted while taking LEF).

    Taking LEF can make it harder for you to fight infections. If you have a fever or think you may have an infection, contact your health-care provider. You may need to stop taking LEF if you are having surgery until you are healed and there is no sign of infection. Please discuss this with your prescriber.

    Taking LEF before or during pregnancy can cause birth defects or even a miscarriage. If you are pregnant or trying to get pregnant, both partners (man and woman) should refrain from taking this drug. LEF can remain in the body for a long time. Typically, it is recommended that LEF is discontinued for women and men for two years prior to getting pregnant. You may be able to take another medication that will help eliminate LEF from your body more quickly if you are planning to get pregnant sooner. If you and your partner are planning to get pregnant, please discuss this with your health-care provider. 

    Any woman who is breastfeeding should also avoid LEF.

    Anyone who has had a previous allergic reaction to LEF should avoid the medication.

  • What are the side effects of LEF?

    Like all medications, taking LEF carries some risk of side effects, which must be balanced with the potential benefits. Overall, the risk of joint damage and permanent disability (resulting from arthritis) is much greater than the risks of side effects from LEF. When monitored properly the vast majority of side effects are rare, generally improve over time and are reversible.

    The most common side effects of LEF is nausea. This usually gets better over time as you get used to taking the medication. LEF can also cause diarrhea, which can be severe. If you develop diarrhea contact your health-care provider. Some people may notice a decreased appetite and weight loss while taking LEF. Let your health-care provider know if you are losing weight while taking LEF.

    In some rare cases, people experience a skin rash, thinning of the hair and the feeling of “pins and needles” or tingling in the hands and feet. Talk to your health-care provider if you experience any of these effects.

    Also, in rare occurrences, LEF can cause an increase in blood pressure. If you already have high blood pressure, please discuss this with your health-care provider before starting LEF.

    LEF may affect your liver and blood counts. This should be closely monitored with routine blood work.

    Lastly, LEF may cause lung problems in rare circumstances. Please contact your health-care provider if you develop new shortness of breath or a new, prolonged cough while taking LEF.

  • What helps to reduce side effects?


    Take LEF as prescribed and contact your health-care provider if you have any concerns while taking the medication.

    Your health-care provider may recommend a lower dose to help reduce some side effects (i.e., stomach upset, hair loss).

    Taking LEF before going to bed can sometimes help you to sleep through any unpleasantness, such as nausea.

    Restricting your intake of alcohol can help avoid potential liver problems.

  • Do I need any monitoring while taking LEF?

    You will need regular blood tests to monitor your liver and blood counts for side effects. When beginning to take LEF, your prescriber may request blood work more frequently (every two weeks) for a period of time. If you have no issues with the medication during this time, blood tests will be required less frequently (every four to 12 weeks).

    Your health-care provider may meet with you regularly to ensure that LEF is adequately controlling your inflammatory arthritis and not causing adverse effects.


This information was last updated November 2017, with expert advice from:

Jason Kielly, B.Sc. (pharm.), Pharm.D.
Assistant Professor, School of Pharmacy, Memorial University of Newfoundland
Clinical Pharmacist, Rheumatic Health Program, Eastern Health

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