Fluoxetine is used to treat depression, obsessive-compulsive disorder (bothersome thoughts that won’t go away and the need to perform certain actions over and over), some eating disorders, and panic attacks (sudden, unexpected attacks of extreme fear and worry about these attacks). Fluoxetine is also used to relieve the symptoms of premenstrual dysphoric disorder, including mood swings, irritability, bloating, and breast tenderness. It is also used along with olanzapine (Zyprexa) to treat depression that did not respond to other medications and episodes of depression in people with bipolar I disorder (manic-depressive disorder; a disease that causes episodes of depression, episodes of mania, and other abnormal moods). Fluoxetine is in a class of medications called selective serotonin reuptake inhibitors (SSRIs). It works by increasing the amount of serotonin, a natural substance in the brain that helps maintain mental balance.
Fluoxetine comes as a capsule, a tablet, a delayed-release (releases the medication in the intestine) capsule, and a solution (liquid) to take by mouth. Fluoxetine may be taken with or without food. Fluoxetine capsules, tablets, and liquid are usually taken once a day in the morning or twice a day in the morning and at noon. Fluoxetine delayed-released capsules are usually taken once a week. Take fluoxetine at around the same time(s) every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take fluoxetine exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.
Summary from MedlinePlus.gov, click for more information.