Can you get in trouble for lying about previous medical history to receive narcotics?

I recently caught my cousin with a large amount of xanax and vicodin and asked where he got it from. We've been close for years and he knows anything he tells me is in confidence and it's totally between him and I. I asked him how he got all of it because I know he's never been prescribed any of these drugs before. He said he went to a doctor and claimed he was just put back on his parents insurance and that he had previously been prescribed 2mg xanax 4 times daily as well as 500mg vicodin 4 times daily and needed to get back on those meds now that he had insurance again. I'm amazed that the doctor went along with it and wrote him those prescriptions even though the doctor even said he couldn't find any medical history about that for my cousin. Here's my question: Will the doctor dig deeper to find out more information about his previous medical history, and if so, can my cousin get into any legal trouble for lying and receiving these narcotics? Or will the doctor just stop giving him the prescriptions? I just want to know so that if there are any legal ramifications I can intervene as soon as possible and hopefully get my cousin to fess up before it's too late for him. Thank you all for any help you can give