I'm surprised that so many people don't know this.

@stonykark
The ingredients change between countries.

@lowqualityfacts

@stonykark @lowqualityfacts

The wiki article has references... 🤷

"In the United States and Canada, the active ingredient is diphenhydramine. In the United Kingdom, the active ingredients of Benadryl are the second-generation antihistamines acrivastine[3] or cetirizine.[4] Benadryl is also sold as a cough medicine in Australia, India and New Zealand containing diphenhydramine, as well as the antitussive dextromethorphan or the expectorant guaifenesin.[5]"

https://en.wikipedia.org/wiki/Benadryl

@stonykark @dgar @lowqualityfacts It actually does happen sometimes even in some cases different across US states. Due to meth users, sudafed notoriously switched from pseudoephedrine to using phenylephrine, which has little effect beyond placebo but the product name remained the same.