Buy Oxycodone Online the Best Painkiller [How long does it take for Oxycodone to work], Oxycodone is an opiate prescribed for moderate to severe pain and may be prescribed for an injury, post-surgery pain relief, or other kinds of severe pain. The regular forms of oxycodone are taken every four to six hours while the extended-release forms are taken every 12 hours. The onset of pain relief action occurs 10 to 15 minutes after taking a single oral dose of medication. For most people, peak pain-relieving effects can be felt between 30 and 60 minutes after taking a dose.