Diphenhydramine/lorazepamAnticholinergic toxidrome secondary to drug overdose and lack of efficacy: case reports A 14-year-old girl developed anticholinergic toxidrome due to diphenhydramine overdose. In addition, she exhibited lack of efficacy during treatment with lorazepam for anticholinergic toxidrome [not all dosages and routes stated].The girl admitted to the emergency department after an ingestion of 100 tablets of diphenhydramine. She received treatment with lorazepam 10mg prior to arrival and another dose of 6mg in the emergency department due to persistent agitation, tachycardia and hypertension; however, no improvement was noted. Her symptoms were consistent with anticholinergic toxidrome. Thus, she was transferred to the PICU, and started receiving treatment with dexmedetomidine drip. Within 13 hours, her anticholinergic symptoms resolved.