Oxycodone is used to relieve pain severe enough to require opioid treatment and when other pain medicines did not work well enough or cannot be tolerated. It belongs to the group of medicines called opioid analgesics (pain medicines). Oxycodone acts on the central nervous system (CNS) to relieve pain.Oxycodone is used to relieve pain severe enough to require opioid treatment and when other pain medicines did not work well enough or cannot be tolerated. It belongs to the group of medicines called opioid analgesics (pain medicines). Oxycodone acts on the central nervous system (CNS) to relieve pain.