Skip navigation

Marijuana and your health

Information on how marijuana can alter brain chemistry and other associated risks

Contact: Erick Fredendall

Medical information in this article was reviewed by Dr. Juliette Perzhinsky​, a CMU Health physician and associate professor of medicine in the CMU College of Medicine.

Following the passage of the statewide legalization of recreational marijuana officially becoming law on Dec. 6, 2018, you may find yourself with questions: How does it affect me? What are the risks?

The public's perception of harm associated with marijuana has drastically declined over the last decade; however, numerous bodies of research have revealed medical risks associated with marijuana use, including — but not limited to — addiction, risk of psychotic episodes, hindered brain development and more.

To learn about CMU's policy prohibiting marijuana on university property and during events, visit the CMU News FAQ. For information on the drug, the health risks and campus resources available to members of the CMU community, read on.

What is marijuana and how does it work?

Marijuana is the common name for the hemp plant, Cannabis sativa. Marijuana contains a mind-altering chemical called delta-9-tetrahydrocannabinol, or THC. The plant's leaves, flowers, seeds and stems are consumed in a variety of methods to induce mind-altering effects. 

The similarity in structure to naturally occurring brain chemicals allows THC to attach itself to parts of the brain that influence pleasure, memory, thinking, concentration, movement, coordination, and sensory and time perception. These disruptions of mental and physical processes induce a state of euphoria that users commonly refer to as getting high.

To learn more about the various chemical changes that occur in the brain when using marijuana, visit the National Institute on Drug Abuse webpage.

What are the short-term effects of marijuana use?

Although it isn't possible to have a fatal overdose of THC one might experience with binge-drinking behavior associated with alcohol use, short-term consumption is not without risk. Recent studies have found marijuana, particularly the high-potency kind available today, can trigger first-episode psychosis in previously unaffected individuals, thereby posing a possible danger to the user or to others. This is especially a risk for people who are susceptible including those with a family history of psychiatric conditions.

Other short-term problems associated with marijuana use include:

  • Motor impairment.
  • Impaired thinking, problem-solving and memory.
  • Nausea and vomiting.
  • Increased heart rate.
  • Extreme paranoia, depressive behavior and hallucinations.
  • Breathing problems due to lung irritation if smoked or inhaled.
  • Limited motivation or energy to participate in day-to-day functions.

While the risks remain present, occasional marijuana users are less likely to experience ongoing problems as a result of consumption in comparison to those who use the substance frequently.

What are the long-term effects of marijuana use?

Numerous studies on marijuana have found heavy and prolonged use can lead to a number of long-lasting, adverse side effects. These range from lung damage to physical and psychological dependency on marijuana.

  • Respiratory problems: Marijuana smoke has been shown to contain many of the carcinogens, toxins and irritants found in tobacco smoke. These harmful agents can lead to conditions including chronic cough, respiratory illness and infection.
  • Memory: Marijuana alters the region in the brain responsible for memory formation, which can lead to problems with specific learning and memory tasks later in life.
  • IQ loss: Heavy use among teenagers and young adults correlated to stunted brain development, with potential loss of IQ* and verbal ability.
  • Lifestyle disruption: Frequent use has been correlated to lower educational attainment, reduced class attendance, poorer academic performance and lower workplace productivity.
  • Mental health disorders: Regular use has been linked to the worsening of symptoms in mental health disorders including schizophrenia, depression and anxiety.
  • Cannabinoid hyperemesis syndrome (CHS): A condition characterized by intense bouts of nausea, vomiting and stomach cramps, is another symptom sometimes experienced by long-term users of marijuana. Learn more about CHS and the research being done to understand how it affects users.
  • Pregnancy complications: Based on current data, marijuana use during pregnancy or while breastfeeding can result in negative effects in the brain development of babies.

Additional research into the long-term effects of marijuana are ongoing, occasionally conflicting with some previous studies, and could change as more rigorous studies are conducted.

*Loss of intellectual quotient (IQ) among individuals with persistent marijuana use disorder who began using heavily during adolescence.


Despite the common perception that marijuana is not addictive, the truth is more complicated. Although marijuana does not share the addictive capacity of alcohol or heroin, research points to a physical and psychological dependency.

As frequent users adapt to the large amount of TCH interacting with neurotransmitters in the brain, a sudden stop can leave people irritable, restless and craving the drug. The National Institute on Drug Abuse defines addiction as when a person cannot stop using the drug even when it interferes with aspects of his or her life.

Where can I go to learn more or get help?

For support, contact any of the following resources:

CMU Student Health Services
Foust Hall 200

CMCREW (independent recovery resource)

CMU Counseling Center
Foust Hall 102

An updated version of the CMU Code of Conduct can be found here.

Photo Associator

Article Photo Title

Photo Title required.

Photo for News Home

Select File
Use This One

Photo for News Feeds

Select File
Use This One