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DMARD (pyrimidine synthesis inhibitor)

Leflunomide

Brand names: Arava

Leflunomide is a disease-modifying antirheumatic drug (DMARD) used in rheumatoid and psoriatic arthritis.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

Loading dosage for patients at low risk for leflunomide -associated hepatotoxicity and leflunomide -associated myelosuppression: 100 mg daily for 3 days. ( 2.1 ) Maintenance dosage: 20 mg daily. ( 2.1 ) Maximum recommended daily dosage: 20 mg once daily. ( 2.1 ) If 20 mg once daily is not tolerated, may decrease dosage to 10 mg once daily. ( 2.1 ) Screen patients for active and latent tuberculosis, pregnancy test (females), blood pressure, and laboratory tests before starting leflunomide tablets.( 2.2 ) 2.1 Recommended Dosage The recommended dosage of Leflunomide is 20 mg once daily. Treatment may be initiated with or without a loading dose, depending upon the patient's risk of leflunomide …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2025-12-17. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Clinical monograph

How it works

Its active metabolite inhibits dihydro-orotate dehydrogenase, reducing pyrimidine synthesis and lymphocyte proliferation.

Prescribing in practice

  • It has a very long half-life — adverse effects can persist for weeks, and an active washout (with colestyramine or activated charcoal) is used for serious toxicity or planned pregnancy.
  • Hepatotoxicity, hypertension, bone-marrow suppression and diarrhoea/weight loss occur; monitor accordingly.
  • It is teratogenic — effective contraception and washout before conception are required (for women and relevant advice for men).

Monitoring

Monitor FBC, liver function and blood pressure regularly, especially early in treatment.

Counselling the patient

  • Report sore throat, fever, bruising, or yellowing of the skin/eyes.
  • Use effective contraception; a washout is needed before pregnancy.
  • Your blood pressure and blood tests will be monitored.

Evidence & guidelines

A conventional DMARD for rheumatoid and psoriatic arthritis, with monitoring and a washout procedure for its long half-life.

Reference: BSR/BHPR RA Guidelines; NICE NG100; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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