Zoloft is an antidepressant that is used to treat depression, anxiety and Zithromax brand name obsessive compulsive disorder. It is a selective serotonin reuptake inhibitor Zithromax brand name (SSRI) which help to increase the amount of serotonin available in the brain. Zoloft produces fewer side effects than older antidepressants called tricyclics, such as Elavil and Tofranil.