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Expected pharmacological effect
Causality assessment · Expected pharmacological effect
Olanzapine and Weight gain: is the FAERS signal real?
A written Bradford Hill assessment of one drug–event pair. The grade is a judgement about the signal, not a statement that this drug causes this event in any one person; FAERS counts are reports, not rates.
Olanzapine ↔ Weight gain
n=6,832 co-reports · PRR 6.2 · ROR 6.5
Olanzapine produces marked weight gain, among the largest of the atypical antipsychotics, through appetite and metabolic effects; 6,832 co-reports give PRR 6.2. The label advises baseline weight monitoring and counselling.
Regulatory basis: olanzapine prescribing information — weight gain; metabolic monitoring.
| Bradford Hill viewpoint | Status | Note |
|---|---|---|
| Temporality (necessary) | met | Weeks to months |
| Strength | met | PRR 6.2 with 6,832 co-reports |
| Consistency | met | Consistent across cohorts |
| Specificity | not established | Weight gain is common |
| Biological gradient | met | Dose/duration-related |
| Plausibility | met | Known appetite/metabolic mechanism |
| Coherence | met | Fits olanzapine's metabolic profile |
| Experiment | n/a | Often a coded trial endpoint |
| Analogy | met | Analogous to clozapine weight gain |
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.
✗ No ClinicalTrials.gov results-posting trial in the top search hits for olanzapine captured weight gain as a tracked adverse event in a usable structure. Weight gain is well captured in trials, though background diet and lifestyle confound comparison.