Olanzapine (antipsychotics) and Weight gain / metabolic syndrome: is the FAERS signal real?
Olanzapine (antipsychotics) ↔ Weight gain / metabolic syndrome
Olanzapine is among the antipsychotics most strongly associated with weight gain and metabolic disturbance — effects that follow from its pharmacology (notably histamine and serotonin-receptor blockade) and that, over time, contribute to diabetes and cardiovascular risk. The weight gain occurs during treatment, is broadly dose-related, and is a leading reason patients stop the drug. The 6,832 co-reports (PRR 6.2) reflect both the real effect and the very large number of people taking atypical antipsychotics.
Regulatory basis: olanzapine prescribing information (weight gain, hyperglycaemia, and metabolic monitoring). Established antipsychotic metabolic-effects literature.
| Bradford Hill viewpoint | Status | Note |
|---|---|---|
| Temporality (necessary) | met | Weight rises during treatment and can partly regress after switching or withdrawal |
| Strength | met | PRR 6 on a very large co-report count |
| Consistency | met | Reproduced across antipsychotic trials and observational studies |
| Specificity | partial | A class effect, strongest for olanzapine and clozapine |
| Biological gradient | partial | Broadly dose-related |
| Plausibility | met | Appetite/histamine and serotonin-receptor effects shift energy balance |
| Coherence | met | Coheres with the labelled metabolic monitoring guidance |
| Experiment | met | A comparative study recorded weight gain several-fold more often on olanzapine |
| Analogy | met | Analogous to weight gain with clozapine and other atypical antipsychotics |
This page's own qualitative read, not an automated/citation-gated assessment.
✓ Trial evidence found — An Observational Study On Metabolic Syndrome Parameters In Schizophrenia Patients Treated With Atypical Antipsychotics (NCT00448630), N=328
| Term (as recorded) | Ziprasidone (n=57) | Risperidone (n=64) | Quetiapine (n=23) | Olanzipine (n=60) | Aripiprazole (n=50) | Amisulpride (n=41) | Other (n=33) |
|---|---|---|---|---|---|---|---|
| Weight gain — General disorders | 2 | 2 | 1 | 12 | 6 | 1 | 0 |
In this observational metabolic-syndrome study, weight gain was reported about six times more often on olanzapine (12 of 60 patients) than on any comparator antipsychotic (2/57 ziprasidone, 2/64 risperidone, 1/23 quetiapine) — a direct comparative confirmation of olanzapine's leading weight-gain liability. View on ClinicalTrials.gov →