Leflunomide vs Hydroxychloroquine: side effects in FDA adverse event reports
At a glance
| Leflunomide | Hydroxychloroquine | |
|---|---|---|
| Drug class | Antirheumatic Agent | – |
| Brand names | – | – |
| FAERS reports | 104,025 | 90,536 |
| Serious | 82% | 75% |
| Death outcome | 9,331 | 6,265 |
| Boxed warning | Yes EMBRYO-FETAL TOXICITY and HEPATOTOXICITY WARNING: EMBRYO-FETAL TOXICITY and HEPATOTOXICITY Embryo-Fetal Toxicity Leflunomide is contraindicated for use in pregn | No |
Signals both drugs share
| Reaction | Leflunomide | Hydroxychloroquine | Label screen (A / B) |
|---|---|---|---|
| Synovitis | 10,363 · PRR 275.3 | 8,328 · PRR 199.7 | Labeled adverse reaction / Not in label — unassessed |
| Glossodynia | 8,702 · PRR 128.9 | 6,867 · PRR 102.8 | Labeled (related wording) / Labeled (related wording) |
| Muscle injury | 4,227 · PRR 215.9 | 3,019 · PRR 135.1 | Not in label — unassessed / Labeled (related wording) |
| Rheumatic fever | 3,226 · PRR 587.9 | 2,381 · PRR 280.5 | Labeled (related wording) / Likely indication confounding |
| Sleep disorder due to general medical condition, insomnia type | 3,116 · PRR 190.4 | 2,401 · PRR 138.1 | Not in label — unassessed / Labeled (related wording) |
| Hepatic enzyme | 85 · PRR 317.4 | 72 · PRR 248.1 | Labeled (related wording) / Not in label — unassessed |
| Pemphigus | 9,382 · PRR 642.9 | 7,446 · PRR 351.1 | Not in label — unassessed / Not in label — unassessed |
| Hand deformity | 8,389 · PRR 367.0 | 6,673 · PRR 243.2 | Not in label — unassessed / Not in label — unassessed |
| Pericarditis | 6,347 · PRR 124.4 | 5,077 · PRR 101.6 | Not in label — unassessed / Not in label — unassessed |
| Helicobacter infection | 5,181 · PRR 210.1 | 3,923 · PRR 145.4 | Not in label — unassessed / Not in label — unassessed |
| Duodenal ulcer perforation | 5,149 · PRR 485.9 | 3,870 · PRR 260.7 | Not in label — unassessed / Not in label — unassessed |
| Folliculitis | 4,922 · PRR 184.7 | 3,344 · PRR 111.0 | Not in label — unassessed / Not in label — unassessed |
| Facet joint syndrome | 2,008 · PRR 360.0 | 1,242 · PRR 151.1 | Not in label — unassessed / Not in label — unassessed |
| Bone erosion | 1,595 · PRR 166.0 | 1,129 · PRR 108.4 | Not in label — unassessed / Not in label — unassessed |
| Deep vein thrombosis postoperative | 1,325 · PRR 429.2 | 1,022 · PRR 254.3 | Not in label — unassessed / Not in label — unassessed |
| Dislocation of vertebra | 1,106 · PRR 200.8 | 854 · PRR 144.7 | Not in label — unassessed / Not in label — unassessed |
| Adjustment disorder with depressed mood | 1,042 · PRR 217.5 | 787 · PRR 148.8 | Not in label — unassessed / Not in label — unassessed |
| Lupus vulgaris | 781 · PRR 392.3 | 626 · PRR 259.4 | Not in label — unassessed / Not in label — unassessed |
| Retinitis | 683 · PRR 140.1 | 537 · PRR 109.9 | Not in label — unassessed / Not in label — unassessed |
| Granuloma skin | 496 · PRR 304.8 | 364 · PRR 182.4 | Not in label — unassessed / Not in label — unassessed |
Labeled signals distinctive to Leflunomide
- Peripheral venous disease — n=1,527, PRR 125.1 Labeled (related wording)
Labeled signals distinctive to Hydroxychloroquine
- None stood out among the strongest labeled signals.
Common questions
Which has more reported side effects, Leflunomide or Hydroxychloroquine?
Leflunomide has 104,025 FAERS reports and Hydroxychloroquine 90,536. More reports does not mean more dangerous: volume follows how widely and how long a drug has been used, prescription vs over-the-counter status, and publicity. The seriousness share (82% vs 75%) is a better like-for-like signal of the kind of problems reported.
Which side effects do Leflunomide and Hydroxychloroquine share?
Both drugs carry disproportionality signals for synovitis, glossodynia, muscle injury, rheumatic fever, sleep disorder due to general medical condition, insomnia type. Shared signals often reflect a shared drug class or the condition both are used for.
Is Leflunomide or Hydroxychloroquine safer?
FAERS cannot answer that: it has no denominator and no comparator. Use this page to see which risks are already on each label and which signals are unlabeled, then check the prescribing information and your clinician for your situation.
Sources: openFDA FAERS pair statistics (OpenPV build 2026-09-14), FDA labels via openFDA, openFDA count queries for seriousness and deaths. Pair chosen because it is a commonly searched comparison. Generated 2026-10-08.