Tylenol PM is a compound medication that consists of acetaminophen (paracetamol) and diphenhydramine. The presence of the latter substance is the feature that makes that brand distributed by Johnson & Johnson unique in the Tylenol row. "PM" in the drug's name refers to the recommended usage of the medication. It means "post meridiem", i.e. this version of Tylenol is usually taken in the evening before going to bed. Diphenhydramine included in the formula together with acetaminophen prevents sneezing, itchying, running nose and other symptoms of the common cold, allergies and hay fever, helping the patient sleep well. So, Tylenol PM is not a sleeping pill, as some people believe. It just spares you breathing, etc difficulties and is conductive to the feeling of calmness, so important for everyone to have a good rest.