Zoloft is a brand name for sertraline HCL and is used in the treatment of depression, excessive anxiety, and obsessive compulsive disorder. Launched in 1992 it has since been used in over 10.2 billion patient days of therapy. The exact mechanism that allows Zoloft to combat these affilictions is still not completely understood but what researchers have noticed is that Zoloft affects the way that serotonin is managed by the human body, Doxycycline pil which then regulates moods and emotions.