Ranitidine (Zantac) and Cancer (breast, prostate, bladder, colorectal, renal): is the FAERS signal real?
Ranitidine (Zantac) ↔ Cancer (breast, prostate, bladder, colorectal, renal)
Reporting over time (stimulated-reporting check)
Reporting spiked in 2014, 2020, 2021, 2022, 2023 — 93% of all 47,105 reports arrived in two years (2021–2022). A burst like this usually follows a regulatory communication, media coverage or litigation advertising rather than a change in the drug's effect; it inflates disproportionality for those years.
Dashed lines: 2019 — FDA NDMA contamination alert; 2020 — FDA requests market withdrawal
Bars: reports per year as a share of all FAERS reports for this drug, 2004–2025; amber = spike year (>3× the median share, ≥50 reports). Source: openFDA count=receivedate, retrieved 2026-10-09.
This is the clearest "mechanism, not mystery" entry on this page. Ranitidine itself is not believed to cause cancer; the problem was contamination. In 2019–2020, independent and FDA laboratory testing found that ranitidine can degrade — especially under heat or over time in storage — into NDMA (N-nitrosodimethylamine), a compound classified as a probable human carcinogen based on animal studies. The elevated cancer signals across multiple unrelated organ systems in this dataset (breast, prostate, colorectal, bladder, renal all flagged independently) is exactly the pattern a systemic carcinogen contaminant would produce, rather than the organ-specific pattern a drug's own pharmacology usually leaves. FDA requested market withdrawal of all ranitidine products in the U.S. in April 2020. This is a textbook example of a real, serious, and ultimately regulatory-confirmed signal — but the causal agent was a manufacturing/stability impurity, not ranitidine's intended pharmacological action.
Regulatory basis: FDA market withdrawal request for all ranitidine products (April 2020), citing NDMA contamination.
| Bradford Hill viewpoint | Status | Note |
|---|---|---|
| Temporality (necessary) | met | Long-term use before diagnosis fits carcinogen-latency expectations |
| Strength | partial | Each organ-specific PRR (38–61) is moderate alone; the real strength is the cross-organ pattern |
| Consistency | met | Replicated across 5 independent organ sites in this dataset |
| Specificity | not established | Deliberately so: the carcinogen is a contaminant, not ranitidine's own pharmacology — a multi-organ pattern is the expected signature of a contaminant, not a specific drug effect |
| Biological gradient | met | FDA found contamination increased with storage time and heat |
| Plausibility | met | NDMA is an IARC/EPA-classified probable carcinogen; degradation chemistry independently confirmed |
| Coherence | met | Multi-organ pattern coheres with systemic contaminant exposure, not with H2-blocker pharmacology |
| Experiment | met | Market withdrawal (2020) is the real-world exposure-removal intervention |
| Analogy | met | Analogous to other nitrosamine-contamination recalls in the same period (valsartan, metformin ER) |
This page's own qualitative read, not an automated/citation-gated assessment.