Olanzapine (Zyprexa^®) is a drug that is licensed to treat schizophrenia and bipolar disorder. This medication works by blocking or lessening the effects of several chemicals in the brain. However, olanzapine is not a cure for bipolar disorder or schizophrenia; it only controls the symptoms of these conditions. Olanzapine comes in tablet form and is usually taken once a day. As with any drug, there are possible side effects with olanzapine. Some of the more common side effects seen with this drug include dizziness, drowsiness, and constipation. A few of the factors that can affect the olanzapine dosage your doctor prescribes include the medical condition being treated, the severity of your condition, and other medical conditions you may have.