Can you mix benadryl and oxycodone?

As a healthcare professional, I would not recommend it. Although Benadryl does not have any adverse effects when taken with oxycodone it can add to the effects of drowsiness and sleepiness which in turn affects your breathing. As you already know, one side effect of Oxycodone is in fact drowsiness, although some people do not actually experience this particular side effect while taking oxycodone, and one of Benadryl's major side effects is also drowsiness, therefore in laimens terms, the combination of the two would probably knock you out. Yet, if you are one of those that does not get sleepy when taking Oxycodone then I don't see why not, because as I stated earlier, there are no known adverse affects between the two. I wouldn't work, drive, or do anything that requires activity until you know for sure how the meds work together should you take them together. It won't hurt you, just be cautious. I hope this helps!!