This is a list of adverse effects of the antipsychotic olanzapine, sorted by frequency of occurrence. Very common Very common adverse effects of olanzapine, occurring more than 10%, include: Weight gain (dose-dependent). Weight gain of over 7% of a person's initial body weight prior to treatment is in this category of very common too with some estimates of its incidence putting it at around 40.6%. This adverse effect is most likely the result of its potent 5-HT2C receptor and H1 receptor blockade (or more specifically inverse agonism). Somnolence (dose-dependent). Tends to produce a moderate amount of sedation, less than clozapine and chlorpromazine but more than aripiprazole, amisulpride, paliperidone and sertindole and approximately that of quetiapine and risperidone. Hyperprolactinemia elevated blood levels of the hormone, prolactin. Prolactin is one of the hormones that plays a key role in lactation. Long-term uncontrolled hyperprolactinaemia can lead to bone demineralisation (osteoporosis) and an increased risk of fractures (breaks). It tends to produce hyperolactinaemia less often than risperidone, paliperidone and the typical antipsychotics but more often than quetiapine and clozapine. Hypertriglyceridaemia (elevated blood triglycerides) Hypercholesterolaemia (elevated blood cholesterol levels) Hyperglycaemia (elevated blood glucose levels). This may be the result of olanzapine's inhibitory effects on the M3 receptor which regulates the release of insulin from the pancreas. Brain shrinkage (dose dependent) Common Common adverse effects of olanzapine, occurring from 1-10%, include: Gynecomastia Extrapyramidal symptoms (EPS) (dose-dependent). Tends to produce less extrapyramidal side effects than typical antipsychotics but more extrapyramidal side effects than sertindole, clozapine and quetiapine. Mild and transient constipation and xerostomia (dry mouth) Dizziness Weight gain of over 15% of one's initial body weight. Is reported to occur in approximately 7.1% of patients. Glucosuria (glucose in the urine. This is a consequence of hyperglycaemia) Accidental injury Insomnia Orthostatic hypotension (a drop in blood pressure that occurs upon standing up) Transient, asymptomatic elevations of hepatic aminotransferases (ALT, AST), especially in early treatment. ALT & AST are liver enzymes which are often tested for as a measure of liver function. Dyspepsia (indigestion) Erectile dysfunction. This is most likely the result of hyperprolactinaemia. Decreased libido. This is most likely the result of hyperprolactinaemia. Rash Asthenia (weakness) Fatigue Oedema the accumulation of fluid in the tissues of the body leading to swelling Akathisia an inner sense of restlessness that presents itself with the inability to stay still Parkinsonism tremor, muscle rigidity, reduced ability to move and being unstable on