Neuroleptic Malignant Syndrome with Low-dose Quetiapine After Venlafaxine Withdrawal: A Case Report

Neuroleptic Malignant Syndrome (NMS) is an idiosyncratic and potentially life-threatening drug reaction. Although uncommon, NMS cases induced by oral quetiapine have been reported. Most reports have predisposing risk factors such as an organic brain disorder, concomitant use of other antipsychotics or lithium, overdose or rapid titration. NMS with low doses of quetiapine is a much rarer clinical picture. Venlafaxine is commonly associated with withdrawal upon discontinuation sometimes as soon as the next day. In this case report, a 40-year-old man treated with venlafaxine for generalized anxiety disorder with symptoms of full-blown NMS after venlafaxine withdrawal, induced by low-dose quetiapine (50 mg), is presented. In accordance with the previous reports, we speculate that venlafaxine withdrawal was a predisposing factor in our case however we also discussed other possible explanations for NMS. Acknowledging the risk of NMS, even with low doses of quetiapine in patients devoid of known risk factors, is of paramount importance for prompt diagnosis and mitigating morbidity and mortality. To our knowledge, this is the first case of NMS with such a low dose of quetiapine without any other known risk factors or substances.