[header] How to spot drug abuse [title] Keep an eye out for problems at work or school. [step] Typically, the first sign of a problem is a drastic drop in attendance or engagement at school or work. Maybe you learn that your teen has been skipping school. 
Or, you are asked to repeatedly lie to your roommate's boss about their " family emergency. " sudden changes in their functioning suggest that something else, possibly drugs, has become a priority for the person.