This page presents data from the FDA Adverse Event Reporting System (FAERS) and the FDA-approved drug label. A report submitted to FAERS does not prove a drug caused the reported event. Always consult a healthcare provider about medications.

Leflunomide

antirheumatic agent

Last updated: August 27, 2026

Preview tracking

Leflunomide is a medication, a antirheumatic agent. According to the FDA-approved label, Leflunomide Tablets, USP are indicated for the treatment of adults with active rheumatoid arthritis (RA). Leflunomide tablets are a pyrimidine synthesis inhibitor indicated for the treatment of adults with active rheumatoid arthritis. ( 1 ). FAERS contains 104,033 submissions naming this drug from 2004 through 2026; the top three reactions cited are drug ineffective, rheumatoid arthritis, and pain.

Most-Reported Reactions

Counts of the reactions most often cited in FAERS submissions that named Leflunomide. Inclusion here does not establish causation - submitters describe what was observed, not what was confirmed. One submission can list several reactions, so the totals exceed the report count.

Patient Demographics

Patient sex and age across the FAERS submissions that named Leflunomide. Percentages here are computed only from submissions where these fields were filled in - many leave them blank.

By Sex

By Age Group

Severity Outcomes

Severity flags recorded across the 104,033 FAERS submissions that named Leflunomide. Each bar shows the count of those reports carrying that flag. A single case can carry more than one (a hospitalization that became life-threatening, for example), so these bars are independent rates - they don't sum to 100%. Inclusion of a case under any flag does not establish that the drug caused the outcome.

Submissions Per Quarter

Quarterly count of FAERS submissions that named Leflunomide. Ups and downs on this chart can track prescribing volume, news cycles, or shifts in how reports get filed, rather than the drug becoming safer or more dangerous.

From the FDA-Approved Label

Excerpts from the official FDA-approved prescribing information for Leflunomide. This is the authoritative source on indications, warnings, and known adverse reactions.

Indications

1 INDICATIONS AND USAGE Leflunomide Tablets, USP are indicated for the treatment of adults with active rheumatoid arthritis (RA). Leflunomide tablets are a pyrimidine synthesis inhibitor indicated for the treatment of adults with active rheumatoid arthritis. ( 1 )

Adverse Reactions (from label)

6 ADVERSE REACTIONS The following serious adverse reactions are described elsewhere in the labeling: Hepatotoxicity [see Warnings and Precautions (5.2) ] Immunosuppression [see Warnings and Precautions (5.4) ] Bone marrow suppression [see Warnings and Precautions (5.4) ] Stevens-Johnson syndrome and toxic epidermal necrolysis [see Warnings and Precautions (5.5) ] Peripheral neuropathy [see Warnings and Precautions (5.7) ] Interstitial lung disease [see Warnings and Precautions (5.8) ] The most commonly reported adverse reactions (≥10%) regardless of relation to leflunomide treatment were diarrhea, respiratory infection, nausea, headache, rash, abnormal liver enzymes, dyspepsia. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Chartwell RX, LLC. at 1-845-232-1683 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch 6.1 Clinical Trials Experience Because clinical studies are conducted under widely varying conditions, adverse reaction rates observed in the clinical studies of a drug cannot be directly compared to rates in the clinical studies of another drug and may not reflect the rates observed in practice. (continues in label)

FDA label effective date: 2025-12-17

Disclaimer

AdverseEvent.ai is not affiliated with the FDA. Adverse-event counts come from the FDA Adverse Event Reporting System (FAERS). Drug labels come from the FDA drug label dataset. A report submitted to FAERS does not prove a drug caused the reported event — always consult a healthcare provider about medications. This site is for informational purposes only and is not medical advice.