Bipolar disorder is a severe mental illness and often occurs with comorbidities like anxiety or alcohol abuse. Thus pregabalin could be a promising drug. We present a case report of a 37-year-old woman with bipolar II disorder suffering from a depressive episode with features of anxiety and increased alcohol consumption. The patient was started on quetiapine as monotherapy. After a few days of add-on pregabalin, we observed suicidal ideations and self-harming behaviour, although expression of anxiety as well as alcohol consumption showed a decrease. When we stopped pregabalin and increased the dosage of quetiapine, suicidal behaviour almost disappeared. In the relevant literature, there is disagreement on the use of pregabalin. On the one hand, pregabalin is described as a safe and well-tolerated drug, and on the other hand, there are also concerns about the suicidal effect of anticonvulsants. In conclusion, we recommend the cautious use of pregabalin and other anticonvulsant drugs in patients with affective disorder. There could be a promising effect on the comorbidities but the effect on mood remains still unclear.