Can i take promethazine codeine syrup with benadryl (diphenhydramine)?

Why?: Promethazine and Benadryl (diphenhydramine) are both antihistamines. The combination of prometh. With Codeine should be used the treatment of uncontrolled coughing. Unfortunately, the purple syrup is frequently abused in a number of unusual ways. To add Benadryl (diphenhydramine) to the combination syrup doesn't make much sense in most circumstances and could lead to at least drowsiness or worse.