BMC Med 15 (1): 95, 2017. doi: 10.1186 / s12916 - 017 - 0845 - 1 Symptoms and Signs of Sedative Toxicity Acute toxicity or overdose The signs of sedative intoxication are depression of deep tendon reflexes, fine lateral-gaze nystagmus, slightly decreased alertness with coarse or rapid nystagmus, ataxia, slurred speech, and postural unsteadiness.