Acetaminophen is a medication used to relieve mild to moderate pain and reduce fever. It is classified as an analgesic (pain reliever) and antipyretic (fever reducer) . Acetaminophen is commonly used to treat headaches, menstrual periods, toothaches, backaches, osteoarthritis, or cold/flu aches and pains. It can also be used to relieve the pain of arthritis caused by the breakdown of the lining of the joints. Acetaminophen works by changing the way the body senses pain and by cooling the body. It is available in various forms such as tablets, chewable tablets, capsules, suspension or solution (liquid), extended-release (long-acting) tablet, and orally disintegrating tablet. Acetaminophen is available without a prescription, but it is important to follow the directions on the prescription or package label carefully, and not to take more than one product that contains acetaminophen. It is also important to check the labels on all your medicines to see if they contain acetaminophen, and ask your pharmacist if you are unsure. Acetaminophen can cause serious liver damage if more than directed is used, and caution is necessary for patients with renal or hepatic impairment or patients with alcoholic liver disease, glucose 6-phosphate dehydrogenase deficiency, or severe hypovolemia.