What is marijuana? How is it used?

Marijuana – also called pot, weed, grass, reefer, Mary Jane – is a greenish-gray mixture of dried, shredded flowers, stems, seeds, and leaves derived from the Cannabis or hemp plant. The most common varieties are Cannabis sativa and Cannabis indica. The main psychoactive chemical in marijuana, responsible for most of the intoxicating effects, is delta-9-tetrahydro-cannabinol (THC).

The vast majority of marijuana users smoke cannabis using hand-rolled cigarettes (joints), pipes, bongs,  and marijuana cigars (blunts). When marijuana is sold or consumed for medicinal purposes, it is often mixed into a variety of foods (edibles) including chocolate, brownies, cookies, or candies. These items can be especially problematic since there is no regulation on the amount of THC contained and no way to regulate the amount consumed.

The Effects of Marijuana Use

When marijuana is smoked, THC and other chemicals in the plant pass from the lungs into the bloodstream, which rapidly carries them throughout the body to the brain. This process produces mood-altering effects as well as other mental and physical disruptions. The effects or results of smoking marijuana are not universal. Many people who choose to smoke marijuana may have an unpleasant experience. For some users, marijuana intoxication can cause anxiety, fear, paranoia, or panic. Excessive marijuana use (in one sitting or over a long duration of time) can also cause acute psychosis, which includes hallucinations, delusions, and a loss of the sense of personal marijuana use at USD identity. This type of reaction is frightening and often leads to hospitalization.

Implications for Long-Term Memory

Despite common belief, there can be long-term consequences of marijuana use. Research indicates that regular marijuana use among adolescents can lead to impaired neural connectivity in areas of the brain that control the “executive functions” such as memory, learning, and impulse control. A recent New Zealand study, found that frequent and persistent marijuana use starting in adolescence was associated with a loss of an average of 8 IQ points measured in mid-adulthood.

Several studies have linked marijuana use to increased risk for mental illness including psychosis/schizophrenia, anxiety, and depression. The amount of drug used, the age of first use, and genetic vulnerability have all been shown to influence this relationship.

Marijuana: Myths and Facts

Myth: Marijuana use increases quality of sleep. Marijuana usage can inhibit your sleep quality.

Fact: THC ingestion decreases both SWS (Slow Wave sleep) and REM (Rapid Eye Movement) sleep. Research indicates that it can take at least one week for the normal sleep cycle to return after last use.

Myth: Marijuana use is a cure for anxiety.

Fact: The most commonly reported side effects of smoking marijuana are intense anxiety and panic attacks. Studies report that about 20-30% of recreational users experience such problems after smoking marijuana. The people most vulnerable are those who have never used marijuana before. (Harvard Mental Health Letter, April 2010)

Myth: Smoking marijuana is a safe alternative to smoking tobacco.

Fact: Marijuana smoke contains 50-70% more carcinogenic hydrocarbons than tobacco smoke. Marijuana users usually inhale more deeply and hold their breath longer than tobacco smokers do, which further increases the lungs’ exposure to carcinogenic smoke. (NIDA, 2010)

Marijuana and…


  • Marijuana can be addictive. The risk of becoming addicted to marijuana is based on a variety of factors including what age a person began using, frequency of use, and a family history of addiction.
  • For marijuana dependent users, quitting can cause mild to moderate withdrawal symptoms including irritability, restlessness, decreased appetite, sleep difficulties, and cravings.
Driving (a.k.a. Drugging and Driving)

  • Driving a motorized vehicle while intoxicated on marijuana is dangerous and illegal.
  • The risk of being involved in an accident doubles after marijuana use.
  • Marijuana significantly disrupts parts of the brain that control judgment, motor coordination, and reaction time.
The Academic Experience

  • Students who choose to smoke marijuana during college can experience significant academic challenges.
  • Smoking marijuana significantly impairs short-term memory (STM) functioning, which vital to learning new information.
  • Students who use marijuana are also more likely to experience “a-motivational syndrome.” This is a diminished or absent drive to engage in typically rewarding activities. Turning in assignments late, missing class lectures, and lack of preparation for exams all lead to negative academic outcomes.
Medical Uses

  • Currently, there are two FDA-approved, THC-based medications (Marinol and Cesamet) in pill form that are prescribed for the treatment of nausea in patients undergoing chemotherapy and to stimulate appetite in patients with wasting syndrome due to AIDS.
  • The possession, use, and sale/dissemination of marijuana (even medical marijuana marijuana for students who possess a cannabis card) is prohibited on USD’s campus. For further information, please reference USD’s Code of Conduct or “The Code” at The Office of Ethical Development and Restorative Practices

If you are concerned about your marijuana use or a friend’s marijuana use, or simply want to learn more, we can help!

Use the brief and confidential marijuana-specific assessment and feedback tool: Marijuana E-Checkup TO GO to explore how your use of marijuana might be impacting your health and college experience.

Contact the Center for Health and Wellness Promotion at (619) 260-4618 for resources and support!