Tylenol PM is an over-the-counter medication that is used as a pain reliever, fever reducer and sleep inducer. It's made of acetaminophen and diphenhydramine HCl.
According to Drugs.com, side effects of Tylenol PM include drowsiness, blurred vision, dry eyes and stomach pain. Allergic reactions can also occur. Tylenol PM should be taken as directed on the label to lessen complications.
Acetaminophen
Acetaminophen is a pain reliever known as a nonopioid analgesic. It's also a fever reducer. According to Medicine Net, it removes pain by elevating the pain threshold, more pain is needed before a person will actually feel it. Acetaminophen reduces fever by instructing the body to lower its temperature. In an April 2008 Tufts Journal article, Ewan McNicol, assistant professor of anesthesiology, says non-opioid analgesics work by "inhibiting an enzyme known as cyclooxygenase (COX). COX is a catalyst for the conversion of a fatty acid contained in cell walls--arachidonic acid--to substances known as prostaglandins."
Acetaminophen comes in many forms, including liquid, gel caps and chewable caplets, in different dosages. It's effective in relieving pain, but it doesn't work on swelling and inflammation.
Liver damage can occur in those who take large amounts of acetaminophen.
Diphenhydramine HCl
Diphenhydramine HCl is also found in Tyelnol PM. It's a sedative that helps the body fall asleep by encouraging the body to produce melatonin. Melatonin is a hormone produced by the pineal gland, which helps regulate sleep cycles.
Diphenhydramine HCl is also an antihistamine. It helps the body counteract allergic reactions.
