Fluoxetine is an antidepressant in a group of drugs called selective serotonin reuptake inhibitors (SSRIs). Fluoxetine affects chemicals in the brain that may become unbalanced and cause depression, panic, anxiety, or obsessive-compulsive symptoms. It is used to treat major depressive disorder, bulimia nervosa (an eating disorder) obsessive-compulsive disorder, panic disorder, and premenstrual dysphoric disorder (PMDD). It may also be used for purposes other than those listed in this medication guide. Despite the availability of newer agents, it remains extremely popular. Over 22.2 million prescriptions for generic formulations of fluoxetine were filled in the United States in 2007, making it the third most prescribed antidepressant. One should not take fluoxetine together with pimozide (Orap), thioridazine (Mellaril), or a monoamine oxidase inhibitor (MAOI) such as isocarboxazid (Marplan), phenelzine (Nardil), rasagiline (Azilect), selegiline (Eldepryl, Emsam), or tranylcypromine (Parnate). As there one may have thoughts about suicide when first start taking an antidepressant, especially if someone is younger than 24 years old. The doctor will need to check at regular visits for at least the first 12 weeks of treatment. SSRI antidepressants may cause serious or life-threatening lung problems in newborn babies whose mothers take the medication during pregnancy. However, one may have a relapse of depression if someone stops taking the antidepressant during pregnancy. If you woman planning a pregnancy, or if she becomes pregnant while taking fluoxetine, she does not stop taking the medication without first talking to the doctor.