Because of its effects on serotonin and norepinephrine, Zoloft is more effective than other antidepressants for some patients. Zoloft works for the majority of patients with major Flagyl medication depression, panic disorder and Flagyl medication obsessive compulsive disorder (OCD). It may also be prescribed off-label for bulimia nervosa, post-traumatic stress disorder, premenstrual dysphoric disorder, and social anxiety disorder.