Allopurinol and DRESS syndrome (drug reaction with eosinophilia and systemic symptoms): is the FAERS signal real?
Allopurinol ↔ DRESS syndrome (drug reaction with eosinophilia and systemic symptoms)
Allopurinol is one of the leading causes of severe cutaneous adverse reactions worldwide — a spectrum that includes DRESS (a systemic hypersensitivity reaction with rash, fever, eosinophilia, and organ involvement), Stevens–Johnson syndrome, and toxic epidermal necrolysis. The risk is strongly genetically determined: the HLA-B*5801 allele confers a markedly elevated risk (especially in Han Chinese, Thai, and Korean populations), and screening is recommended before starting the drug in high-risk groups. The reaction is delayed (typically 2–8 weeks after initiation), immune-mediated, and can be fatal, particularly in patients with chronic kidney disease or in elderly patients. It is one of the best-documented pharmacogenomic adverse reactions in medicine.
Regulatory basis: allopurinol prescribing information (severe skin reactions); HLA-B*5801 screening recommendation (ACR/CPIC). Established DRESS/SJS/TEN pharmacogenomics literature.
| Bradford Hill viewpoint | Status | Note |
|---|---|---|
| Temporality (necessary) | met | Reaction is delayed but consistently follows initiation by 2–8 weeks |
| Strength | met | PRR 18 for DRESS and 11 for TEN, both large |
| Consistency | met | Replicated across registries and pharmacogenomic studies worldwide |
| Specificity | met | Allopurinol is a leading cause of severe cutaneous adverse reactions |
| Biological gradient | met | Risk rises with dose and with renal impairment (higher oxypurinol levels) |
| Plausibility | met | HLA-restricted T-cell activation of oxypurinol-specific clones is well described |
| Coherence | met | Coheres with the broader DRESS/SJS/TEN immunogenetics literature |
| Experiment | met | HLA-B*5801 screening and renal dose-adjustment reduce risk in practice |
| Analogy | met | Analogous to carbamazepine/abacavir HLA-linked hypersensitivity syndromes |
This page's own qualitative read, not an automated/citation-gated assessment.
✓ Trial evidence found — allopurinol vs placebo in heart failure with hyperuricaemia (NCT00987415), N=253
| Term (as recorded) | Allopurinol (n=128) | Placebo (n=125) |
|---|---|---|
| Rash (serious) | 2 | 0 |
| Rash (non-serious) | 11 | 3 |
Rash appears more often on allopurinol, consistent with its well-known cutaneous propensity — but this small trial tracked only generic “rash,” not DRESS or SJS/TEN, which are rare enough to be invisible at this size. The severe-reaction risk is established from pharmacovigilance and HLA-stratified studies, not from trial AE tables. View on ClinicalTrials.gov →