Leflunomide (Arava)

Raw research findings for this medication. Mostly single studies, not curated or confirmed robust.

About Leflunomide

What it is

Leflunomide is a disease-modifying antirheumatic drug (DMARD): the body turns it into teriflunomide, which blocks DHODH, an enzyme activated lymphocytes need to make DNA building blocks. It is used for rheumatoid arthritis and psoriatic arthritis. Its active form stays in the body for months unless washed out with cholestyramine. It is sold as Arava.

How genes come into it

Leflunomide is converted to teriflunomide partly by CYP1A2 and CYP2C19, and teriflunomide is carried by ABCG2. Studies have looked at CYP1A2 for side effects, at DHODH, its target, and at ESR1, ESR2 and PTPN22 for response. The findings come from a few studies, and there is no CPIC or DPWG guideline.

What research found

Every published finding on gene variants and Leflunomide. Upload your DNA file to see which of these rows apply to you.

Rated evidence (4 rated variants)

PharmGKB weighs all studies of a variant and rates how strong the evidence is, from 1A (strongest) to 4.

ESR1 rs9340799: Level 3. Efficacy: Rheumatoid arthritis. 1.

DHODH rs3213422: Level 3. Efficacy: Rheumatoid arthritis. 1.

ESR1 rs2234693: Level 3. Efficacy: Rheumatoid arthritis. 1.

CYP1A2 rs762551: Level 4. Toxicity: Rheumatoid arthritis. 2.

Metabolism (3 findings)

Studies of how quickly the body processes this medication.

CYP1A2 rs12720461: Allele T is not associated with metabolism of leflunomide in people with Arthritis as compared to genotype CC.

CYP1A2 rs2069526: Allele G is not associated with metabolism of leflunomide in people with Arthritis as compared to genotype TT.

CYP1A2 rs762551: Allele A is not associated with metabolism of leflunomide in people with Arthritis as compared to genotype CC.

Response (9 findings)

Studies of how well it worked in people carrying a variant.

DHODH rs3213422: Genotype CC is associated with increased clinical benefit to leflunomide in people with Arthritis, Rheumatoid as compared to genotypes AA + AC.

ESR1 rs2234693: Genotype TT is associated with increased response to leflunomide in women with Arthritis, Rheumatoid as compared to genotype CC.

ESR1 rs9340799: Genotype AA is associated with increased response to leflunomide in women with Arthritis, Rheumatoid as compared to genotypes AG + GG.

PON1 rs705379: Genotype GG is associated with increased clinical benefit to leflunomide in people with Rheumatoid arthritis as compared to genotypes AA + AG.

Side effects (1 finding)

Studies of side effects in people carrying a variant.

PTPN22 rs2476601: Genotypes AA + AG is not associated with discontinuation of leflunomide in people with Arthritis, Rheumatoid as compared to genotype GG.

Study findings and evidence levels: PharmGKB (CC BY-SA 4.0). Guidelines: CPIC and DPWG, as bundled in PharmCAT. Most studies were done mainly in people of European ancestry.

Related Drugs

More drugs from the same category

Iguratimod (DMARDs)

Orencia (DMARDs)

Actemra (IL-6 Inhibitors)

Not a prescribing recommendation. This page is educational information about pharmacogenomic research and clinical guidelines - it is not medical or dosing advice, and not a prediction of how any medication will work for you. Never start, stop, or change a medication or dose based on it; talk to your doctor or pharmacist, who can order clinical-grade testing if appropriate.

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Content updated September 2026.

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