The most readily abused substance among US teens is marijuana. The high availability, perception of less harm, media and peer influences are a few of the reasons that marijuana use is rising among youth and teens. In fact, over 45% of U.S. teens will have tried marijuana at least one in their lifetime by the time they finish high school. 
Parents play an influencing role in a teen’s decision to use marijuana and other substances. Talking openly with your children and staying actively engaged in their lives will help prevent underage marijuana use. Help your child/youth sort out fact from myth will help them make the soundest decision on whether or not they use marijuana.
The following are tips on for how to discuss marijuana with your child: 
If you suspect your child may be using marijuana, some common signs of marijuana use are:
A common misconception among teenagers is that marijuana is safer to use than alcohol or other drugs. When discussing marijuana with your child/teen, knowing the consequences of underage marijuana use is a helpful prevention tool.
1 US Department of Health and Human Services NIH Publication 13-40362
2 American Academy of Child and Adolescent Psychiatry, http://www.aacap.org/AACAP/Families_and_Youth/Facts_for_Families/Facts_f...