Long term diphenhydramine use has been linked to dementia.
A family member alerted me to this a couple years ago.
https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2091745
OH OH OH!!!
I learned something the other day about Benadryl (diphenhydramine!)
It turns out that if a person is subject to restless leg syndrome, the Benadryl will exacerbate it.
I have a family member who they tried it, and it is true. They were taking it at night to get drowsy, and developed RLS. Then stopped the benedryl No RLS.