Toladryl is a derivative of Diphenhydramine that can cross the blood-brain barrier and exhibits oral activity, with antihistamine and anticholinergic properties. Its anticholinergic effects are approximately a tenth of those seen with Diphenhydramine, yet it offers 2-4 times the protection against lethal doses of histamine in guinea pigs. The side effects of Toladryl are fewer and milder compared to Diphenhydramine; however, at higher doses, it may cause symptoms such as insomnia, agitation, and disorientation related to the central nervous system. Toladryl is utilized in the research of allergic diseases.