Hydrocodone 5/325 mg is a prescription pain medication that combines hydrocodone, an opioid pain reliever, with acetaminophen (the "325 mg" part). This combination is used to relieve moderate to severe pain, such as pain from injury, surgery, or certain medical conditions. Hydrocodone works by changing the way the brain and nervous system respond to pain, while acetaminophen can help increase the effects of hydrocodone and also reduce fever.