Over the years, it has been shown that various psychopharmaceuticals cause alterations on thyroid function. The objective of this review is to summarize the most important thyroid side effects associated with them. Special attention is paid to antidepressants, which are widely used and whose side effects are not receiving the attention they deserve.This review presents three cases of patients who were undergoing treatment with venlafaxine. Before the start of treatment, we asked for an analytical with thyroid profile in which no change was observed. After establishing treatment, a decrease in total T4 and free T4 was observed, TSH remained unchanged.It is important to note the need for systematic evaluation of thyroid function at the beginning of an antidepressant treatment, and perform their monitoring controls. We cannot forget that the clinical of hypothyroidism sometimes presents with depressive symptoms, which could mask the effectiveness of treatment.