Benadryl Side Effects on Brain Health and Dementia Risk First-generation antihistamines like diphenhydramine (Benadryl) block histamine but also strongly block acetylcholine, a neurotransmitter essential for attention and memory. That anticholinergic effect explains many of the cognitive risks. 🧠 Memory problems and slower thinking Diphenhydramine crosses the blood–brain barrier and impairs attention, working memory, and reaction time. Controlled studies show worse vigilance and cognitive perfo

Why it is important to understand the risks of diphenhydramine (Benadryl). #medication #sideeffects #doctor | Zachary Rubin, MD