this double-blind randomized clinical trial is performed on adults who are referred to the psychiatry outpatient clinics of Shahid Sadughi University of Medical Science. A convenience sample of 50 patients of both genders aged 18-54 years is entered in this study. Participants are included in this study if they fulfill the criteria of major depressive disorder according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR).,
and we use the 17-item Hamilton Depression Rating Scale (HDRS).
Patients with other mental illnesses, such as severe major depression, , bipolar disorder or anxiety-, alcoholic or drug abuse patients,patients with other significant medical diseases ,psychotic patients, pregnant women and breastfeeding mothers,and patients who had been treated with any antidepressants within 4 weeks before the study are excluded.
the patients should be medically stable. Using simple randomization, patients who meet all criteria for enrollment are randomly allocate into 2 treatment groups. Both patients and psychiatrist are blinded to the type of treatment.citalopram is commenced with the initial dose of 10 mg daily,and gradually increases to 40 mg daily.venlafaxine ER starting dose is 37.5 mg daily,then gradually increases to 150 mg a day.f0llow up visits is every a 2 weeks for 8 weeks.we ask patients about any possible side effects, and calculated a HDRS total score.