As a parent, understand that your child goes through different phases while growing up. It doesn’t mean that you should never trust your child or he’ll keep drifting away from you; what you need to understand is the fact that your child will lie. You need to pretend to believe in him.
Occasionally raise topics as such when you’re gathered round in the family room and gain feedback from him on it. Indulge in playing “Truth and Dare” games and make your child confess. Well, you adopt whichever measure just to make him admit to his mistake but what you need to now is how to tackle the situation after that.
Will you let your wrath loose? If so, forget that your child will ever confess anything to you, ever. Sit down with him; counsel him. Bring to his notice the cons of using drugs. Don’t stop treating your child differently; treating him differently will only aggravate the pain within him and make him fear admitting his mistakes.
Do not even stop trusting your child; let him go out with his friends and have a good time but keep him in check my calling him up every thirty minutes for any reason. It could be a random “when will you return?” or “your sister needs to be picked, can you do it?” call or anything else. Give your child sufficient responsibilities so that he finds it difficult to resort to any such activities. Limit his social activities to weekends; he deserves the time off from school.