Order m366 online now from curedog.com , Hydrocodone is used to relieve severe and persistent pain in people who are expected to need an opioid pain medication around the clock for a long time and who cannot be treated with other pain medications.Hydrocodone is in a class of medications called opiate (narcotic) analgesics. It works by changing the way the brain and nervous system respond to pain.pain severe enough to require an opioid analgesic and for which alternative treatments are inadequate