Lema GF, et al. - A double-blinded, randomized control trial is conducted to compare the effectiveness of intravenous (IV) ketamine with IV tramadol for the prevention of shivering in patients who underwent cesarean delivery under spinal anesthesia. According to the outcome obtained, the prophylactic administration of low-dose IV ketamine or IV tramadol is successful for decreasing the incidence and intensity of shivering. They suggest low-dose IV ketamine or tramadol prophylaxis for parturients undergoing cesarean section under spinal anesthesia.