The 750 mg refers to the Tylenol portion. Hydrocodone goes up to 10 mg, and it is how it is dosed. 200 mg Fentanyl would stop your breathing rather quickly. Hopefully, it was mcg.
But, Ruben and gliderdad are right. You do build up a resistance, but if 2 mg of Dilaudid doesn't work, then 8 mg likely would, etc.
