<p><strong>Symptoms</strong>: Antihistamine drugs in toxic doses produce a complex of CNS excitatory and depressant effects. Accidental ingestion in small children has resulted in convulsions and sometimes death.<br />
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<strong>Management</strong>: As there is no specific antidote, treatment should be symptomatic and supportive. Induction of vomiting should only be used immediately after ingestion as the sedative action of any absorbed antihistamine can lead to life-threatening pulmonary aspiration during emesis. Gastric lavage with a cuffed endotracheal tube in situ may be useful for some time after ingestion of antihistamines as their anticholinergic action slows down gastric emptying. Stimulants should not be used as they may precipitate convulsions. Diazepam or short-acting barbiturates may be used to control convulsions. Vasopressors may be used to treat hypotension. Mechanical support of respiration may be required if respiration is seriously depressed. Continuous ECG monitoring is recommended if cardiac toxicity develops, which can be treated with centrally-acting anticholinesterases such as physostigmine.</p>