Can benadryl and zantac and Zyrtec all be taken at the same time?

I asked my doctor this same question. She says it's not advisable, but if your Allergies are very bad, you can take Zyrtec in the morning, and then Benadryl before bed. Zyrtec makes some people drowsy (although not me) and Benadryl makes most people drowsy, so mixing them can put you to sleep. Zyrtec dries out your system, as well, so drink extra water. Don't do this too often. Too much antihistamine can be bad for you, but doing this occasionally is okay.