Vicodin is a prescription medication combining two active ingredients: hydrocodone bitartrate (5 mg) and acetaminophen (500 mg). Hydrocodone is an opioid analgesic that alters the perception and response to pain in the brain, while acetaminophen is a non-opioid pain reliever and fever reducer that enhances the effects of hydrocodone. This combination is used to relieve moderate to severe pain.