Oxycontin 20mg er is a brand name for a prescription medication containing oxycodone, which is a powerful opioid analgesic used to manage severe pain. It's typically prescribed for the treatment of chronic pain conditions that require around-the-clock pain relief when other medications are not sufficient. However, Oxycontin, like other opioids, carries a risk of dependence, addiction, and overdose, especially when used improperly or for extended periods. It's classified as a Schedule II controlled substance in the United States due to its high potential for abuse.