The Corps will DEFINITELY know about it. They don't play around. First and foremost, you are a trained killer. They can't take chances like that in the field, especially when they are giving you all crazy types of vaccines that could interact w/the meds you are taking. Hence, they are anal about medical records. . . . . come to think of it. . . . they are anal about EVERYTHING!!!!!!!!!!!!!!!!!!!!!
Finally, they take blood samples multiple times! Shit stays in your blood a LOT longer than it does in urine. I advise against it. If they find out your were lying, you could get discharged and lose your bennies. The Corps is like no other branch of service.
Be up front about it.