Olanzapine is an atypical antipsychotic. Olanzapine is structurally similar to clozapine and quetiapine, but is classified as a thienobenzodiazepine. The benefits of olanzapine in schizophrenia are difficult to determine as more than half of people in trials quit before the six week completion date. In light of this, the positive effects of olanzapine appear equivalent to typical antipsychotics with fewer extrapyramidal side effects but greater weight gain. When compared to other atypical antipsychotics, the available data suggests that olanzapine may be slightly more effective; however, it produced more weight gain and other metabolic problems. Evidence does not support the use of atypical antipsychotics including olanzapine in eating disorders. Olanzapine is no less effective than lithium or valproate, and more effective than placebo in treating bipolar disorder.