During the use of antidepressants, mania/hypomania can be seen and be associated with mood disorders. Although they are less frequent, hypomanic or manic situations associated with discontinuation or reduced dosage of antidepressants have also been reported. The presented case is about the phenomenon of exacerbation during a manic episode while reducing the dose of venlafaxine, which has been used for a year. A 25-year-old female patient diagnosed as depression, has been followed regularly in the clinic for 18 months. The dose of venlafaxine was reduced to 75 mg/day from 150 mg/day, which she has been using for a year without psychiatric symptoms. After five days, she applied to the clinic with manic symptoms including irritability, grandiosity, insomnia and an increase in goal-directed activities, and she was placed under psychiatric and organic evaluations for diagnostic differential. There was no organic pathology that could be associated with mania, and family history was also negative. It was thought to be a mania that was induced by antidepressant discontinuation. Venlafaxine was discontinued and olanzapine of 10 mg/day and lorazepam of 3 mg/day were started and she was followed by our clinic. Exacerbation of the disease related to discontinuation of psychotropics and symptoms related with discontinuation of the medication should be carefully monitored. The emergence of withdrawal symptoms or the exacerbation of depressive symptoms, related to the discontinuation of antidepressants is common. Withdrawal symptoms related to discontinuation of antidepressants occur within hours or days. Symptoms like restlessness, headache, nausea and anxiety are observed and the patient becomes normal shortly after s/he starts taking the drug. In our case, five days after the dose reduction, mood symptoms were more dominant than withdrawal symptoms. The manic/hypomanic shift while taking antidepressants is a common; they are frequently expected within the first 4-8 weeks of the first usage of the medication. As our case used this medication for 18-weeks with no mood elevation during this period, this suggests that we do not think the diagnosis is not a drug-induced manic episode. In their research, where manic states depending on antidepressant discontinuation was studied, Narayan et al. used four criteria: a manic state that starts after stopping or reducing the dose of an antidepressant, no pharmacological confounders are present that could account for the manic state, e.g., stimulant misuse or stoppage of an antimanic drug prior to the onset of the manic state. Continuous antidepressant treatment should have been administered for at least four weeks before the manic state begins. Symptoms begin within one week of antidepressant stoppage or dose reduction. Our case meets all the criteria mentioned above. Decisions of discontinuation of antidepressant medication and follow-up of this process must be done carefully. It should be considered that manic symptoms that were developed in this process could be related with mood episodes due to discontinuation of the medication. In our case, Venlafaxine was regularly used for 18-months. It was used at a dose of 150 mg/day for one year; when it was reduced to 75 mg/day, the manic symptoms began.