Tylenol PM is a painkiller, sleep aid and a fever reducer. It contains acetaminophen and an antihistamine called diphenhydramine, which reduces the production of histamine, notes Drugs.com.
The combination drug helps treat runny nose, headache, watery eyes, sneezing, and fever or pain from an allergic reaction and the common cold. An overdose of acetaminophen can damage the liver and even lead to death. Although it is rare, Tylenol PM can cause serious skin irritation. If a patient experiences skin redness or a rash that causes peeling and blistering, he should stop using the drug and seek urgent medical attention, states Drug.com.