Impacts of a six-month venlafaxine intake on serum prolactin levels in patients with major depressive disorder

Objective: Antidepressants may increase serum prolactin levels. The purpose of the study is to explore the effects of six months of venlafaxine intake on the serum prolactin level of patients with major depressive disorders.

Methods: Seventy-eight patients with major depressive disorders, who had applied to the psychiatry clinics consecutively, participated in the study. Structured Clinical Interview for DSM-IV Axis I Disorders and the Hamilton Depression Rating Scale were administered to all participants. Levels of serum prolactin, FT3, FT4 and TSH of each participant were measured before the venlafaxine treatment. After one month and sixth month of the venlafaxine treatment, levels were remeasured. The study was completed with sixty-five cases.

Results: There is no significant difference between serum prolactin levels measured at the beginning and in the first month of the treatment. Serum prolactin level measured at the beginning of the treatment had increased significantly by the sixth month of the treatment. Serum prolactin levels measured in the first month of the treatment had increased significantly by the sixth month of the treatment. Galactorrhea did not occur in any cases. 

Conclusion: Even though galactorrhea did not occur in any case despite the long-time use of venlafaxine, the serum prolactin levels increased within the normal limits. Therefore, clinicians should monitor the serum prolactin levels of the patients during the venlafaxine treatment without waiting for galactorrhea symptoms.