Oxycodone 40mg is the best opioid drug that is used to relieve extreme pain. Oxy 40mg has two formulations, i.e., immediate-release and extended-release formulations. Oxycodone 40 mg may not work as well if used for more than one or two months. The patient should take Oxycodone 40 mg a day by mouth with a glass of water as prescribed by their doctor. Take Oxycodone 40 mg old or new with or without food according to the prescription. You can also take it with food if you have nausea.