You may not be sure that your son or daughter has misused drugs. A recent study indicates that parents are often the last to know when their teen has a serious problem with substance abuse. So when a parent realizes that there's a problem, it's likely a big one. Act quickly. Before talking to your child consult a health care professional.
(1) Fisher, S.L., Bucholz, K.K., Reich, W., Fox, L., Kuperman, S., Kramer, J., Hesselbrock, V., Dick, D.M., Numberger, Jr., J.I., Edenberg, H.J., & Bierut, L.J. (2006). Teenagers are right: Parents do not know much: An analysis of adolescent-parent agreement on reports of adolescent substance use, abuse, and dependence. "Alcoholism: Clinical and Experimental Research", 30, 1699-1710.