Warfarin vs Clopidogrel Bisulfate: side effects in FDA adverse event reports
At a glance
| Warfarin | Clopidogrel Bisulfate | |
|---|---|---|
| Drug class | – | – |
| Brand names | Warfarin Sodium | – |
| FAERS reports | 126,271 | 101,649 |
| Serious | 80% | 86% |
| Death outcome | 16,103 | 11,097 |
| Boxed warning | 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 | Yes DIMINISHED ANTIPLATELET EFFECT IN PATIENTS WITH TWO LOSS-OF-FUNCTION ALLELES OF THE CYP2C19 GENE See full prescribing information for complete boxed warning. Ef |
Signals both drugs share
| Reaction | Warfarin | Clopidogrel Bisulfate | Label screen (A / B) |
|---|---|---|---|
| Retroperitoneal haematoma | 268 · PRR 23.0 | 167 · PRR 16.9 | Not in label — unassessed / Not in label — unassessed |
| Retroperitoneal haemorrhage | 261 · PRR 19.5 | 161 · PRR 14.3 | Not in label — unassessed / Not in label — unassessed |
| Subdural haemorrhage | 237 · PRR 15.6 | 174 · PRR 13.8 | Not in label — unassessed / Not in label — unassessed |
| Abdominal wall haematoma | 285 · PRR 28.4 | 125 · PRR 14.1 | Not in label — unassessed / Not in label — unassessed |
| Spinal epidural haematoma | 86 · PRR 29.7 | 136 · PRR 65.4 | Not in label — unassessed / Not in label — unassessed |
| Haematoma muscle | 101 · PRR 15.5 | 95 · PRR 18.0 | Not in label — unassessed / Not in label — unassessed |
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)
Labeled signals distinctive to Clopidogrel Bisulfate
- Blood loss anaemia — n=187, PRR 18.8 Labeled (related wording)
- Respiratory tract haemorrhage — n=84, PRR 33.6 Labeled (related wording)
- Insulin autoimmune syndrome — n=82, PRR 64.6 Labeled adverse reaction
- Acquired haemophilia — n=78, PRR 17.6 Labeled adverse reaction
Common questions
Which has more reported side effects, Warfarin or Clopidogrel Bisulfate?
Warfarin has 126,271 FAERS reports and Clopidogrel Bisulfate 101,649. 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 (80% vs 86%) is a better like-for-like signal of the kind of problems reported.
Which side effects do Warfarin and Clopidogrel Bisulfate share?
Both drugs carry disproportionality signals for retroperitoneal haematoma, retroperitoneal haemorrhage, subdural haemorrhage, abdominal wall haematoma, spinal epidural haematoma. Shared signals often reflect a shared drug class or the condition both are used for.
Is Warfarin or Clopidogrel Bisulfate 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.