Zyprexa^® (olanzapine) is a drug that is licensed to treat schizophrenia and bipolar disorder. In clinical studies of Zyprexa for schizophrenia, people taking Zyprexa experienced improvements in their schizophrenia symptoms (including hallucinations and suspiciousness), compared to those not taking Zyprexa. In previous studies, Zyprexa was also shown to be effective for bipolar disorder treatment. In these studies, Zyprexa was shown to be effective when used alone or with other bipolar disorder medications. As with any drug, there are possible side effects with Zyprexa. Some of the more common side effects seen with this drug include dizziness, drowsiness, and constipation.