Teaching your teenager to avoid drugs starts with straightforward discussion about the consequences of taking mind-altering substances. The U.S. Department of Education recommends the following guidelines. Talk about the immediate and long-term effects of consuming drugs, tobacco or alcohol: bad breath, stained teeth, increased risk of cancer and liver disease. Discuss impaired judgment and related risks of mind altering substances such as driving under the influence or getting into dangerous sexual situations. Mention the role of drugs in interfering with a student's future plans, such as going to college and eventually starting a family. Point out the dangers of alcohol, tobacco and other drug use in relation to pregnancy, including birth defects in newborns. Warn your teen about the hazards of combining drugs. Discuss medical marijuana and the debate over legalization of marijuana. Explain that the component of marijuana with medicinal value is delta-9-terhydrocannabinol (THC). It can be prescribed by doctors in pill form, which lacks the cancer-causing chemicals of smoked marijuana. Praise and encourage your teen when he or she makes good decisions and achieves long-worked-for goals.