How would i know if my son is on cocaine?

Change in behavior: You might notice changes in behavior -- could be irritable and agitated when using, rushed, and intense. When coming down (or crashing) he could sleep for long periods, and be very depressed. Unexplained absences from school, slacking off in studies, spending more money than usual, perhaps stealing from you. Drug testing too. Please talk w/your doctor about all this.