Zoloft (or sertraline HCL) is used for the treatment of depression, obsessive compulsive disorder and excessive anxiety. It affects the way that serotonin is managed by the body; serotonin being a chemical that is part of an important drug family known as selective serotonin re-uptake inhibitors (or SSRI's). By modifying the levels of serotonin in the brain, SSRI's help to combat certain afflictions such as depression, excessive anxiety and obsessive compulsive disorder.In a professional tone: The exact mechanism that allows Zoloft to combat these affilictions is still not completely understood, however what researchers have noticed is that Zoloft affects the way that serotonin is singulair a presecription managed by the human body. Serotonin is part of a drug family known as selective serotonin re-uptake inhibitors (or SSRI's). SSRI's increase the level of serotonin in the brain by inhibiting (not preventing) its breakdown.