Is Tylenol Safe During Pregnancy? Understanding Risk Factors Seeking Health USMLE Step 2 CK Question of the Day: Altered Mental State After Over the counter pain reliever and Prescription Hydrocodone acetaminophen Osmosis Blog Acetaminophen, also known as Tylenol, is used to help with pain & to reduce fever. However, taking too much acetaminophen can be harmful to the liver which filters out toxins & N acetylcysteine (NAC)