Paracetamol and salicylate testing: routinely required for all overdose patients?

To determine whether it is necessary to routinely measure serum salicylate levels in addition to serum paracetamol levels in alert overdose patients who deny ingestion of that substance.

Prospective observational study of overdose patients attending an urban emergency department.

A total of 171 patients attended with an alleged overdose. Thirty-seven patients were excluded; 24 patients had a reduced conscious level (Glasgow Coma Scale <15), nine patients could not recall the time of overdose and four patients had a staggered overdose. In all, 47.0% (63/134) claimed to have taken paracetamol and 5.2% (7/134) claimed to have taken salicylate. No patient who denied taking paracetamol or salicylate subsequently tested positive for them. In all, 51.5% (69/134) of patients reported that they had taken alcohol at the time of their overdose.

Given the relatively low clinical risk and evident symptoms and signs from salicylate overdose, routine testing may not be required for fully conscious asymptomatic patients who deny taking it. The risks of delayed toxicity and lack of initial symptoms in those ingesting paracetamol suggests that continued routine testing is necessary.