Did you know that grapefruit juice can increase oxycodone’s peak plasma concentration levels by up to 50%? That’s because grapefruit juice interferes with how your body metabolizes oxycodone into noroxycodone and noroxymorphone (the weaker byproducts), so oxycodone remains in your system longer, while also shifting metabolism toward oxymorphone, which is a much stronger opioid. 20 milligrams of oxycodone with grapefruit juice is functionally equivalent to 30 milligrams of oxycodone without it. Crazy.

https://www.researchgate.net/publication/43226168_Grapefruit_Juice_Enhances_the_Exposure_to_Oral_Oxycodone