Carbamazepine overdose recognized by a tricyclic antidepressant assay

Altered mental status in an adolescent presents a diagnostic challenge, and the clinician depends on clinical evaluation and laboratory studies to determine therapy and prognosis. We report the case of an adolescent with altered consciousness caused by carbamazepine overdose with a positive tricyclic antidepressant level to alert clinicians to the cross-reactivity of carbamazepine with a toxicology screen for tricyclic antidepressants.