leflunomide Side Effects
Also known as: Arava
Analysis of 102,095 adverse event reports submitted to the FDA from 2004 to 2025.
Total Reports
102,095
Death-Related
8,456
8.3% of reports
Hospitalizations
27,652
27.1% of reports
Top Indication
Rheumatoid Arthritis
Most Reported Adverse Reactions
Who Reports Side Effects
Gender Distribution
Age Distribution
Reporting Trend by Year
Reactions in Death Reports
Top reactions reported in 8,456 reports where death was an outcome. These are voluntarily reported and do not establish causation.
| Reaction | Reports |
|---|---|
| OFF LABEL USE | 2,411 |
| RHEUMATOID ARTHRITIS | 2,231 |
| SYSTEMIC LUPUS ERYTHEMATOSUS | 2,196 |
| GENERAL PHYSICAL HEALTH DETERIORATION | 2,146 |
| GLOSSODYNIA | 2,120 |
| TYPE 2 DIABETES MELLITUS | 2,093 |
| RASH | 2,072 |
| JOINT SWELLING | 2,064 |
| HAND DEFORMITY | 2,063 |
| FATIGUE | 2,058 |
| PSORIATIC ARTHROPATHY | 2,051 |
| SYNOVITIS | 2,040 |
| DUODENAL ULCER PERFORATION | 2,017 |
| HYPOAESTHESIA | 2,017 |
| FIBROMYALGIA | 2,013 |
| INFUSION RELATED REACTION | 1,993 |
| HEPATIC ENZYME INCREASED | 1,990 |
| HYPERTENSION | 1,985 |
| SWELLING | 1,983 |
| HELICOBACTER INFECTION | 1,976 |
Reactions in Hospitalization Reports
Top reactions in 27,652 reports where hospitalization was an outcome.
| Reaction | Reports |
|---|---|
| DRUG INEFFECTIVE | 6,726 |
| RHEUMATOID ARTHRITIS | 6,005 |
| PAIN | 5,662 |
| ARTHRALGIA | 5,457 |
| FATIGUE | 4,987 |
| OFF LABEL USE | 4,890 |
| RASH | 4,745 |
| JOINT SWELLING | 4,576 |
| ARTHROPATHY | 4,339 |
| DRUG HYPERSENSITIVITY | 4,027 |
| SYNOVITIS | 3,959 |
| CONDITION AGGRAVATED | 3,941 |
| DRUG INTOLERANCE | 3,900 |
| NAUSEA | 3,826 |
| ABDOMINAL DISCOMFORT | 3,823 |
| DIARRHOEA | 3,729 |
| HEADACHE | 3,715 |
| HYPERSENSITIVITY | 3,657 |
| INFUSION RELATED REACTION | 3,604 |
| VOMITING | 3,534 |
Nearby — Related Medications
What the FAERS Data Reveals About leflunomide Side Effects
The FDA Adverse Event Reporting System (FAERS) contains 102,095 voluntary reports linked to leflunomide and its brand equivalents (Arava), spanning 2004 through 2025. Of those, 8,456 (8.3%) listed death as an outcome and 27,652 (27.1%) involved hospitalization. The most common indication reported alongside adverse events was Rheumatoid Arthritis.
Demographic breakdowns help contextualize who is being exposed to the drug. Of reports with known sex, 82% were female and 18% male; age distribution skews toward 45-64, with 29,335 reports in that bracket. The single most reported reaction is drug ineffective with 36,983 submissions, followed by rheumatoid arthritis and pain.
FAERS is a signal-detection tool, not a scorecard. Reports are voluntary, and a single case may list multiple suspect drugs, so numbers above should not be read as incidence rates or per-patient risk. Widely prescribed drugs naturally accumulate more reports than niche therapies even when individual risk is low. These aggregates are useful for spotting patterns that merit further pharmacovigilance, not for choosing between medications. This page is for educational reference only and is not medical advice — speak with a licensed clinician about any side-effect concerns.
Read our methodology — how this data is sourced, computed, and verified.