Most parents assume that if their children are not "acting" high and they don't find drugs in their belongings, that they're not using illegal substances. But the truth is, many teenage drug users are quite adept at hiding their habit from their parents. Classic "high" symptoms like red eyes and grogginess may be the last thing you notice -- and they probably have some super creative places to stash their addictive substances. So, as a parent, it's important to be aware of these more subtle signs that your teen may be using drugs.

A change in friend groups.

If your child suddenly stops spending time with his or her old friends and seems to have adopted a new friend group, this could be a sign that he or she is using. You should be especially concerned if your teen refuses to bring these new friends by the house and instead insists on spending time with them only outside of the home -- where parents are not present.

A sudden loss of interest in favorite activities.

Often times, when teens first start doing drugs, the drugs become the activity in which they are most interested. They may lose interest in other activities they once loved, like playing instruments, participating in sports, or attending community events. Your teen may make excuses for this loss of interest, such as "I've just moved on" or "I never really liked that anyways." 

Missing money.

Keep an eye on your teen's spending habits. If they seem to be going through a lot of money but you don't notice any new toys, games, or other items that they could have purchased with that cash, then you have to wonder where the money is really going. Frequently asking you for money with no explanation as to what it's needed for -- or an excuse that you can see right through -- is also a sign of substance use. Some teens may even steal from their parents' wallets and purses.

Demanding privacy.

If your teen always used to welcome you into their life and space but suddenly seems more private and withdrawn, this could be a sign of substance use. They may be seeking to hide the drugs themselves, or they could be trying to stay away when they fear they're displaying behavior that would out them as high.

If you suspect your teen may be using drugs, approach them calmly in a non-confrontational manner. Let them know they are not in trouble, but that you just want to help. Then, seek guidance from an addiction recovery specialist, or a company like Lifeline, who has experience working with teenagers.