Acyclovir
FDA Adverse Event Reporting System · 2025 window
Rank #65 by volume
2025 report counts
- Total adverse-event reports
- 8,028
- Classified as serious
- 5,890
- Reports with fatal outcome
- 1,023
- Fatality share of serious reports
- 17.4%
- Rank in window (by total report volume)
- #65 of 500
Top reported reactions (serious-only)
| Reaction (MedDRA PT) | 2025 reports |
|---|---|
| Off Label Use | 557 |
| Drug Ineffective | 438 |
| Death | 388 |
| Pneumonia | 303 |
| Fatigue | 292 |
| Diarrhoea | 260 |
| Pyrexia | 249 |
| Acute Kidney Injury | 248 |
| Neutropenia | 237 |
| Nausea | 208 |
Important caveats
FAERS report counts are a reporting signal, not a clinical assertion of causation. Higher report volumes correlate with: larger treated populations, established manufacturer pharmacovigilance infrastructure, sicker patient populations (specialty biologics for serious disease will always attract more reports than common over-the-counter agents), and reporter familiarity with the reporting workflow.
The paid FAERS Signal Surveillance product adds the disproportionality analysis (Information Component, Empirical Bayes Geometric Mean, Proportional Reporting Ratio) that normalizes these confounders and surfaces emerging signal against the FAERS baseline. See the product page.
For the canonical FDA record, see the FAERS Public Dashboard.