FDA has approved Prozac as the treatment of major depression (MDD), obsessive compulsive disorder (OCD), bulimia nervosa and panic disorder. Prozac proved its efficacy for depression in 6-week long double-blind controlled trials where it also relieved anxiety and improved sleep. Prozac was more effective against placebo for the prevention of depression relapse when the patients, who originally responded to Prozac, were treated for a further 38 weeks. It was found out in placebo-controlled trials that Prozac therapy is effective both in geriatric and pediatric depression.

Physicians can prescribe Prozac for treatment OCD both in adults and children. As against to depression treatment higher doses of Prozac have been more effective in treatment of Obsessive–compulsive disorder. Prozac approved itself as perfect drug in treatment of patients suffering from panic disorder. Using Prozac therapy in such patients leads to exceeding reduction of frequency of panic attacks. Quantity of binge-eating and purging episodes of bulimia nervosa can be significantly decreased if Prosac is taken. It was proved that using placebo for the prevention of bulimia nervosa is not nearly as good as long-termed (year-long) Prozac treatment.