The effects of acute toxicity from ACTIFED Syrup may include drowsiness, incoordination, weakness, irritability, palpitations, hypertension, convulsions and difficulty with micturition.
Overdosage may result in nausea, vomiting, sympathomimetic symptoms including central nervous system stimulation, insomnia, tremor, mydriasis, anxiety, agitation, hallucinations, seizures, palpitations, tachycardia, hypertension and reflex bradycardia. Other effects may include dysrhythmias, hypertensive crisis, intracerebral haemorrhage, myocardial infarction, psychoses, rhabdomyolysis, hypokalaemia, and ischemic bowel infarction. Drowsiness has been reported with overdose in children.
Overdosage of an H1 receptor antagonist may result in CNS depression, hyperthermia, anticholinergic syndrome (mydriasis, flushing, fever, dry mouth, urinary retention, decreased bowel sounds), tachycardia, hypotension, hypertension, nausea, vomiting, agitation, confusion, hallucinations, psychosis, seizures, or dysrhythmias. Rhabdomyolysis and renal failure may rarely develop in patients with prolonged agitation, coma or seizures.
The treatment of overdosage is likely to be symptomatic and supportive. Necessary measures should be taken to maintain and support respiration and control convulsions. Gastric lavage should be performed if indicated. Catheterisation of the bladder may be necessary. Alpha-adrenergic blockade may be required to treat hypertensive crises and beta-adrenergic blockade for the control of supra-ventricular dysrhythmias. If desired, the elimination of pseudoephedrine can be accelerated by acid diuresis or by dialysis.