A patient diagnosed with major depressive disorder who has a history of non-adherence to medications presents to the outpatient clinic with complaints of feeling lightheaded, nausea, irritability and anxiety. Nurse Practitioner suspects that the patient is experiencing which of the following syndromes?

A. Serotonin Syndrome: Serotonin syndrome typically presents with agitation, hyperreflexia, tremor, diaphoresis, hyperthermia, and autonomic instability. While nausea can occur, lightheadedness and irritability alone are not hallmark features, and this syndrome usually results from excessive serotonergic activity rather than abrupt discontinuation. B. Discontinuation syndrome: Antidepressant discontinuation syndrome occurs when SSRIs or SNRIs are stopped abruptly or doses are missed. Symptoms include lightheadedness, nausea, irritability, anxiety, flu-like sensations, and sleep disturbances. The patient’s history of non-adherence and these symptoms are consistent with this syndrome. C. Parasympathetic syndrome: There is no recognized clinical condition called “parasympathetic syndrome.” Autonomic dysfunction in discontinuation syndrome is not classified under this term. D. Neuroleptic malignant syndrome: NMS is a rare, life-threatening reaction to antipsychotics, presenting with hyperthermia, muscle rigidity, autonomic instability, and altered mental status. The patient’s symptoms do not match this severe presentation.