Zoloft (sertraline) is used for the treatment of depression, anxiety, and obsessive-compulsive disorder. Launched in 1992, it has been used in over 10 billion patient days Side effects of doxycycline hyclate therapy. Zoloft is a SSRI drug that increases the level of serotonin in the brain by inhibiting its breakdown. So why take Zoloft? Because it's an SSRI drug and easier on your liver...