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Causality: well established
Causality assessment · Causality: well established
Phenytoin and Gingival hypertrophy: is the FAERS signal real?
A written Bradford Hill assessment of one drug–event pair. The grade is a judgement about the signal, not a statement that this drug causes this event in any one person; FAERS counts are reports, not rates.
Phenytoin ↔ Gingival hypertrophy
n=85 co-reports · PRR 60.6 · ROR 60.9
Phenytoin causes fibrous gingival overgrowth in a substantial minority of long-term users, related to concentration, oral hygiene and age; 85 co-reports give an extreme PRR of 60.6. The label lists gingival hyperplasia and advises good dental hygiene and monitoring.
Regulatory basis: phenytoin (Dilantin) prescribing information — gingival hyperplasia.
| Bradford Hill viewpoint | Status | Note |
|---|---|---|
| Temporality (necessary) | met | Months of therapy |
| Strength | met | PRR 60.6, an extreme signal |
| Consistency | met | Reproduced across cohorts |
| Specificity | met | Fairly specific to phenytoin |
| Biological gradient | met | Concentration-related |
| Plausibility | met | Known fibroblast-proliferation mechanism |
| Coherence | met | Fits phenytoin's connective-tissue effect |
| Experiment | n/a | Not a short-term trial endpoint |
| Analogy | met | Analogous to cyclosporine gingival overgrowth |
This table is this page's own qualitative read of the literature cited above, not an automated or citation-gated assessment — see the note at the bottom of this page.
✗ No ClinicalTrials.gov results-posting trial in the top search hits for phenytoin captured gingival hypertrophy as a tracked adverse event in a usable structure. Epilepsy trials were too short and did not code gingival changes as adverse events.