Clopidogrel vs Warfarin: side effects in FDA adverse event reports
At a glance
| Clopidogrel | Warfarin | |
|---|---|---|
| Drug class | – | – |
| Brand names | – | Warfarin Sodium |
| FAERS reports | 197,000 | 126,271 |
| Serious | 81% | 80% |
| Death outcome | 21,779 | 16,103 |
| Boxed warning | Yes DIMINISHED EFFECTIVENESS IN POOR METABOLIZERS The effectiveness of clopidogrel is dependent on its activation to an active metabolite by the cytochrome P450 (CY | Yes BLEEDING RISK Warfarin sodium can cause major or fatal bleeding [see Warnings and Precautions (5.1) ] . Perform regular monitoring of INR in all treated patient |
Signals both drugs share
| Reaction | Clopidogrel | Warfarin | Label screen (A / B) |
|---|---|---|---|
| Retroperitoneal haemorrhage | 253 · PRR 12.0 | 261 · PRR 19.5 | Labeled adverse reaction / Not in label — unassessed |
| Retroperitoneal haematoma | 229 · PRR 12.3 | 268 · PRR 23.0 | Labeled (related wording) / Not in label — unassessed |
| Spinal epidural haematoma | 123 · PRR 29.5 | 86 · PRR 29.7 | Not in label — unassessed / Not in label — unassessed |
Labeled signals distinctive to Clopidogrel
- Gastrointestinal haemorrhage — n=8,285, PRR 11.5 Labeled adverse reaction
- Upper gastrointestinal haemorrhage — n=1,605, PRR 11.1 Labeled (related wording)
- Ulcer haemorrhage — n=998, PRR 18.3 Labeled (related wording)
- Acute coronary syndrome — n=774, PRR 10.8 Labeled — boxed warning
- Thrombotic thrombocytopenic purpura — n=456, PRR 15.7 Labeled — boxed warning
- Diverticulum intestinal haemorrhagic — n=249, PRR 13.0 Labeled (related wording)
- Blood loss anaemia — n=216, PRR 11.3 Labeled (related wording)
Labeled signals distinctive to Warfarin
- Calciphylaxis — n=729, PRR 110.2 Labeled — boxed warning
- Vascular calcification — n=134, PRR 23.6 Labeled (related wording)
- Catheter site pruritus — n=84, PRR 17.5 Labeled (related wording)
Common questions
Which has more reported side effects, Clopidogrel or Warfarin?
Clopidogrel has 197,000 FAERS reports and Warfarin 126,271. 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 (81% vs 80%) is a better like-for-like signal of the kind of problems reported.
Which side effects do Clopidogrel and Warfarin share?
Both drugs carry disproportionality signals for retroperitoneal haemorrhage, retroperitoneal haematoma, spinal epidural haematoma. Shared signals often reflect a shared drug class or the condition both are used for.
Is Clopidogrel or Warfarin 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.