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 how to order valtrex online combat these affilictions is still not completely understood, however what researchers have noticed is that Zoloft affects the way that serotonin is managed by the human body. Serotonin is part of a drug family known as selective serotonin re-uptake inhibitors (or how to order valtrex online SSRI's). SSRI's increase the level of serotonin in the brain by inhibiting (not preventing) its breakdown.