particularly those of the head and neck Patients may develop torticollis, bruxism, tongue protrusion, or oculogyric crisis Dystonic reactions are unrelated to the amount of ingested phenothiazine They may or may not occur after the first dose Their onset is to 40 hours after ingestion of a single dose of phenothiazine This marked delay between ingestion and clinical manifestations often interferes with obtaining an accurate history of ingestion Fortunately, although painful and distressing, dystonic reactions are rarely life threatening and usually resolve quickly after administration of anticholinergics The clinical chemistry of the newer antipsychotic agents is varied and complex CNS depression, seizures, prolongation of the QT interval, and α-adrenergic blockade–mediated hypotension are common Treatment of acute phenothiazine intoxication depends on the severity of ingestion The autonomic signs are most often transient and require no treatment In patients with moderate or severe overdoses, the potential for life-threatening manifestations requires prompt evaluation of vital signs, GI decontamination (if ingestion was within an hour of ED arrival), vascular access, and cardiac monitoring Pressors such as norepinephrine (see Chapter 10 Shock ) may be used to correct the hypotension In those rare instances of hypertension, the use of nitroprusside (see Chapter 37 Hypertension ) may be indicated Severe arrhythmias should be treated aggressively Attention should be directed to the treatment of temperature instability and other autonomic disturbances Dystonic reactions are effectively controlled by the IM or IV administration of diphenhydramine in a dose of to mg/kg (max 50 mg/dose) Repeat this dose in 15 to 20 minutes if no effect is noted An alternative agent is benztropine mesylate (1 to mg for an older child/adolescent) This agent reportedly causes less sedation than diphenhydramine Another potential alternative, especially in younger children, is diazepam (0.1 to 0.2 mg/kg) After resolution of the dystonic reaction, continue oral treatment for an additional 24 to 72 hours to prevent recurrences Salicylates CLINICAL PEARLS