Tylenol PM Extra Strength Caplets contain 500mg of acetaminophen and 25mg of diphenhydramine hydrocholoride in each caplet. The acetaminophen acts as a pain reliever and fever reducer, and is used to treat headaches, muscle aches, arthritis, colds, fevers, toothaches and backaches while the diphenhydramine hydrochloride helps treat sleeplessness and provides effective treatment for short-term treatment of insomnia or acute insomnia. Tylenol PM Extra Strength is non-habit forming when used as directed.