marijuanaMarijuana is at the center of a passionate debate, and there are often exaggerated, or even false claims made by those on each of the opposing sides. What matters is knowing the facts, and they can be difficult to find in the middle of so much hype. Regardless of changing laws, or its potential role in developing new medical treatments, marijuana use has risks, especially if you are a teen.


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What is it?

A green and brown mix of dried flowers, stems, seeds and leaves from the hemp plant Cannabis sativa. The main active chemical is THC (tetrahydrocannabinol), which moves quickly through the bloodstream to the brain and other organs throughout the body.39

The Risks

THC acts on specific targets in the brain, called cannabinoid receptors. Ordinarily, these receptors are activated by brain chemicals similar to THC that are part of a neural communication system, and play an important role in brain development and function. Marijuana over activates this system, causing impaired coordination, difficulty with thinking and problem solving, and disrupted learning and memory.

Because it impairs coordination and judgment, marijuana use can more than double a driver’s risk of being in an accident. And when used in conjunction with alcohol, the combined result is worse than either substance alone.

Your brain goes through significant development during your teen and young adult years, and marijuana’s effects on the developing brain create risks unique to that time period. Following marijuana use, a teen’s decrease in cognitive abilities can last much longer than an adult’s, as long as several weeks since last use. With regular use (daily or nearly daily), the alterations to the brain caused by marijuana can become chronic, and lead to weakened verbal communication skills, lowered learning capabilities and a shortened attention span.40

There is also an association between chronic marijuana use and mental illness. A link has been demonstrated with later development of psychosis, and the risk increases for those who start young. Associations have also been found with other mental health problems such as depression, anxiety, and suicidal thoughts among adolescents, although more research is needed to better understand these connections.


Marijuana can be addictive – it affects the brain’s reward centers in similar ways as all other addictive substances – and the likelihood of addiction increases considerably for those who start young. When marijuana use becomes daily, or nearly daily, alterations to the brain can lead to an inability to perceive any negative impact.

In addition to the possible effects on your cognitive development and mental health, marijuana smoke is an irritant to the lungs, and frequent marijuana smokers can develop many of the same respiratory problems as tobacco smokers, such as daily cough and phlegm production, more frequent acute chest illness, and a greater risk of chest infections.


Marijuana has the potential to cause problems in your daily life, or make existing problems worse. It limits your brain’s effectiveness, slows down thinking, and impairs coordination and judgment. And while you’re young and still maturing, marijuana can have a long-lasting, negative impact on your developing brain.