Buy vicodin online Vicodin is a prescription pain reliever that combines hydrocodone, an opioid, and acetaminophen, a non-opioid analgesic. It is used to treat moderate to severe pain that doesn't respond to non-opioid treatments. Vicodin works by blocking pain signals in the brain while reducing fever and discomfort. Due to its opioid content, it carries a risk of dependence and abuse, and should only be taken under medical supervision.