What health effects does getting high on oxycodone and then smoking marijuana cause?

Does one exacerbate the effects of the other?

Oxycodone is also percocets, "oxy", "percs" etc

Has anyone tried this combination?

I'm concerned about a friend. I know the weed can affect short-term memory and stuff, but does the oxycodone do anything bad to the brain too?

: http://alcoholdrugstreatment.info/what-health-effects-does-getting-high-on-oxycodone-and-then-smoking-marijuana-cause