Answer: Tylenol PM is the trademark for a mixture of paracetamol(acetaminophen) and diphenhydramine, distributed by Johnson & Johnson. It is marketed as a combined analgesic and sedative, or more simply, pain reliever and sleep aid, intended to treat occasional headaches and minor aches and pains with accompanying sleeplessness.Acetaminophen alone is sold as simply Tylenol, while diphenhydramine alone is marketed at Simply Sleep.This medication, in general, does not seem to be having any adverse side-effects but should be taken occassionally or regularly only doctor's advise and should not exceed the limit. THIS IS VERY IMPORTANT.