Transdermal rivastigmine as a therapeutic option in severe diphenhydramine-induced anticholinergic toxicity: A case report and literature review.

Diphenhydramine overdose is a common toxicological emergency characterized by anticholinergic symptoms such as delirium, hallucinations, and cardiovascular instability. Physostigmine, a centrally acting acetylcholinesterase inhibitor, is the standard antidote but is currently unavailable within the United States due to supply limitations. We present the case of a 21-year-old female with confirmed diphenhydramine overdose (3600 mg) who demonstrated rapid clinical improvement after administration of a 9.5 mg/24-h rivastigmine transdermal patch. This case supports growing evidence suggesting that rivastigmine may serve as a safe and effective alternative when physostigmine is not accessible.