Metoclopramide and Tardive dyskinesia: is the FAERS signal real?
Metoclopramide ↔ Tardive dyskinesia
Reporting over time (stimulated-reporting check)
Reporting spiked in 2010, 2011, 2012, 2013 — 91% of all 13,205 reports arrived in two years (2011–2012). 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: 2009 — FDA boxed warning for tardive dyskinesia
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 single largest PRR among the pairs on this page, and the underlying mechanism is textbook: metoclopramide is a dopamine D2-receptor antagonist, the same pharmacological class responsible for antipsychotic-induced tardive dyskinesia. FDA's 2009 boxed-warning decision followed continued spontaneous reports concentrated in patients who had taken the drug for more than 3 months, and published analyses since have identified metoclopramide as the single most common cause of drug-induced movement disorders overall — not just among gastric-motility agents, but across all drug classes. Risk rises sharply with treatment duration and cumulative dose, which is why the boxed warning specifically limits use beyond 12 weeks except in rare cases. This is one of the best mechanistically-understood adverse drug reactions in this dataset — a predictable, class-wide, dose/duration-dependent effect, not merely a statistical coincidence.
Regulatory basis: FDA boxed warning (2009), metoclopramide prescribing information.
| Bradford Hill viewpoint | Status | Note |
|---|---|---|
| Temporality (necessary) | met | Onset after months–years of cumulative dosing, consistent with the mechanism |
| Strength | met | PRR 335, one of the largest on this page |
| Consistency | met | Replicated across decades, same pattern as other D2 antagonists |
| Specificity | partial | Not unique to metoclopramide — shared across the D2-antagonist class |
| Biological gradient | met | Risk rises with treatment duration/cumulative dose |
| Plausibility | met | D2 receptor antagonism — same mechanism as antipsychotic-induced TD |
| Coherence | met | Fits established class pharmacology |
| Experiment | partial | 12-week duration limit (boxed warning) functions as a real-world exposure-reduction intervention; not an RCT |
| Analogy | met | Direct analogy to antipsychotic-induced tardive dyskinesia |
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.