Fluoxetine is a class of antidepressants, belonging to the SSRI class of antidepressants, whose main effect is to block the reuptake of 5-hydroxytryptamine by central 5-hydroxytryptamine receptors and to elevate the level of 5-hydroxytryptamine in the brain to improve depressive symptoms, mainly used to treat depression and obsessive-compulsive disorder, but also to treat bulimia nervosa. Some people with antidepressants experience weight changes after use, but fluoxetine has less effect on weight, so it can treat bulimia nervosa. Fluoxetine is an antidepressant and its main therapeutic effects are to improve depression, improve anxiety, and improve bulimia nervosa symptoms. Fluoxetine has a slow onset of action. Therefore, at the beginning of early treatment, patients do not feel the therapeutic effects of the drug, and what occurs are adverse drug reactions, such as gastrointestinal adverse reactions. At this time, patients will have mild nausea or diarrhea, and they need to continue to take the drug, and the adverse reactions will be tolerated gradually in about 1 week, and the effects of the drug will appear in about 4 weeks. Therefore, in the early stage, the drug should never be discontinued at will, but should be adhered to, and the symptoms, reactions, and changes should be observed when the therapeutic effect appears.