A case of diphenhydramine intoxication showing prolonged false positive tricyclic antidepressant in the urine assay

Abstract Background The urine immunochromatographic assay is a useful screening tool for patients suspected of acute drug intoxication in emergency conditions. Diphenhydramine shows symptoms similar to those tricyclic antidepressant (TCA) intoxication. Case presentation We examined case diphenhydramine showing cerebellar ataxia and prolonged false positive results TCA the urine. test showed persistently even 60 h after patient's initial screening. observed negative conversion 90 Discussion Considering similarities clinical between intoxication, physicians should consider possibility cross-reactivity diagnosis patient with unknown Conclusion present suggests that overdose may cause show as