Risperidone and Weight gain: is the FAERS signal real?
Risperidone ↔ Weight gain
Reporting over time (stimulated-reporting check)
No reporting spike: the pair's share of the drug's reports is fairly stable over time (busiest two years hold 26% of 9,059 reports), so stimulated reporting is unlikely to explain the signal.
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.
Risperidone, like quetiapine, is a second-generation antipsychotic whose metabolic effects include substantial weight gain — a labeled, dose- and duration-related consequence of the class, with the risk varying meaningfully between agents. In a randomized head-to-head trial of risperidone versus quetiapine XR, "weight increased" was recorded in roughly 6% versus 5% of patients. The very high FAERS PRR reflects that weight gain is both common and reliably reported, but the effect itself is well established, not a statistical curiosity.
Regulatory basis: risperidone prescribing information (weight gain among the most common adverse reactions); FDA class metabolic warning for atypical antipsychotics.
| Bradford Hill viewpoint | Status | Note |
|---|---|---|
| Temporality (necessary) | met | Weight rises after treatment begins, over weeks to months |
| Strength | met | PRR 513 here; a consistent effect in trials and cohorts |
| Consistency | met | Reproduced across studies and across the antipsychotic class |
| Specificity | partial | Class effect, with real differences between individual agents |
| Biological gradient | met | Weight change tracks with dose and duration |
| Plausibility | met | Receptor-mediated appetite/metabolic effects are well described |
| Coherence | met | Coheres with the antipsychotic metabolic-syndrome literature |
| Experiment | partial | Weight loss on switching or withdrawal supports causality |
| Analogy | met | Shared with olanzapine, quetiapine, and other atypicals |
This page's own qualitative read, not an automated/citation-gated assessment.
✓ Trial evidence found — risperidone vs quetiapine XR in schizophrenia (NCT00600756)
| Term (as recorded) | Risperidone (n=402) | Quetiapine XR (n=391) |
|---|---|---|
| Weight increased (other events) | 25 | 18 |
Roughly 6% of risperidone patients and 5% of quetiapine XR patients had weight gain recorded — a clean, randomized confirmation of the expected class effect, with risperidone slightly ahead in this trial. View on ClinicalTrials.gov →