Leflunomide: Side Effects, Uses & Monitoring
Leflunomide tablets are indicated in adults for the treatment of active rheumatoid arthritis (RA): to reduce signs and symptoms to inhibit structural damage as evidenced by X-ray erosions and joint space narrowing to imp
- Data source
- FDA labeling via NIH DailyMed (label 2fcef74c…)
- Label version
- current
- Last reviewed
- 2026
Reported adverse reactions
Reactions listed in current FDA labeling, with the highest frequency reported across summarized placebo-controlled trials.
| Adverse reaction (as reported in labeling) | Reported frequency* |
|---|---|
| Respiratory infection | 32% |
| Diarrhea | 27% |
| Headache | 21% |
| Nausea | 19% |
| Abnormal liver enzymes | 17% |
| Alopecia | 17% |
| Dyspepsia | 13% |
| Rash | 12% |
| Injury accident | 11% |
| Hypertension | 10% |
| Mouth ulcer | 10% |
| Sinusitis | 10% |
| Back pain | 9% |
| Arthralgia | 9% |
| Abdominal pain | 8% |
| Gl/abdominal pain | 8% |
| Joint disorder | 8% |
| Bronchitis | 8% |
| Flu syndrome | 7% |
| Dizziness | 7% |
*Highest percentage reported for the active moiety across placebo-controlled trial tables in current FDA labeling. Values reflect trial reporting, not your individual risk.
Labeled uses (from FDA prescribing information)
Leflunomide tablets are indicated in adults for the treatment of active rheumatoid arthritis (RA): to reduce signs and symptoms to inhibit structural damage as evidenced by X-ray erosions and joint space narrowing to improve physical function (see CLINICAL STUDIES ). Aspirin, nonsteroidal anti-inflammatory agents and/or low dose corticosteroids may be continued during treatment with leflunomide tablets (see PRECAUTIONS - Drug Interactions – NSAIDs ). The combined use of leflunomide tablets with antimalarials, intramuscular or oral gold, D penicillamine, azathioprine, or methotrexate has not been adequately studied. (See WARNINGS - Immunosuppression Potential/Bone Marrow Suppression ).
Conditions associated with Leflunomide in labeling
Frequently Asked Questions
What is Leflunomide used for?
FDA labeling lists the approved uses shown above under "Labeled uses." This summary is informational; only a qualified prescriber can determine whether a medication is appropriate for you.
What are the most commonly reported side effects of Leflunomide?
The table above shows adverse reactions and the highest frequencies reported in placebo-controlled trials summarized in current FDA labeling for Leflunomide. Individual risk varies.
Does Leflunomide require lab monitoring?
Monitoring needs vary. Ask your healthcare provider whether any lab tests apply while taking Leflunomide.
Where does this information come from?
All clinical facts on this page were extracted from the current FDA-registered product labeling for this ingredient, published by manufacturers through NIH DailyMed. See the source link below.
Medical disclaimer: Educational content extracted from public FDA labeling. Not medical advice. Always consult a qualified healthcare professional before starting, stopping, or changing any medication.