Sertraline hydrochloride (trademark names Zoloft and Lustral) is an antidepressant of the selective serotonin reuptake inhibitor (SSRI) class. It was introduced to the market by Pfizer in 1991. Sertraline is primarily used to treat major depression in adult outpatients as well as obsessive–compulsive, panic, and social anxiety disorders in both adults and children. In 2007, it was the most prescribed antidepressant on the U.S. retail market, with 29,652,000 prescriptions.

The efficacy of sertraline for depression is similar to that of older tricyclic antidepressants, but its side effects are much less pronounced. Differences with newer antidepressants are subtler and also mostly confined to side effects. Evidence suggests that sertraline may work better than fluoxetine (Prozac) for some subtypes of depression. Sertraline is highly effective for the treatment of panic disorder, but cognitive behavioral therapy in combination with sertraline is a better treatment for obsessive-compulsive disorder than sertraline alone. Although approved for social phobia and posttraumatic stress disorder, sertraline leads to only modest improvement in these conditions. Sertraline also alleviates the symptoms of premenstrual dysphoric disorder and can be used in sub-therapeutic doses or intermittently for its treatment.