Zyprexa^® (olanzapine) is a drug that is licensed to treat schizophrenia and bipolar disorder. The prescription medication works by blocking or lessening the effects of several chemicals in the brain. Zyprexa comes in tablet form and is usually taken once a day. As with any drug, there are possible side effects with Zyprexa. A few of the more common side effects seen with this drug include dizziness, drowsiness, and constipation. Some of the factors that can affect the dose of Zyprexa that your healthcare provider prescribes include the medical condition being treated, the severity of your condition, other medical conditions you may have, and other medications you may be currently taking.