Marijuana, also known as pot, weed, and a variety of other names, comes from the Cannabis sativa or Cannabis indica plant, and it’s the most commonly used illegal drug in the U.S., with over 22 million users each month.1
In recent years, discussions of federally legalizing marijuana for recreational and medical use have brought more attention to its potential risks and benefits. Often, these discussions point to the dangers of usage among adolescents—but teenagers aren’t the only demographic at risk.2
To understand the important facts about using marijuana, we need to consider a few factors like effects on the brain, changes in potency over time, the impact of usage among young people, the risk of addiction, and more.
How Marijuana Affects the Brain
Marijuana’s main psychoactive ingredient is delta-9-tetrahydrocannabinol or THC. THC binds to cannabinoid receptors in the brain and activates them, disrupting typical neurological functioning and causing a myriad of effects, including a high.3
Typically, these cannabinoid receptors react to a neurotransmitter called anandamide. Because THC is so chemically similar to this natural brain chemical, THC is able to bind to the cannabinoid receptors and change typical communication between neurons.3,4
When you smoke or consume marijuana, the THC in the marijuana activates the parts of the brain that contain the most cannabinoids receptors. This is what causes the desirable effects or high.4
The short-term effects of marijuana use include:4
- Mood changes
- Impaired coordination
- Altered senses
- Altered perception of time
- Impaired problem-solving
- Cognitive issues
- Memory problems
Hallucinations, delusions, and psychosis are typically only associated with extremely high doses or high potency marijuana.4
Long-term marijuana use affects the brain in a number of ways. Here are some facts about marijuana and its long-term effects:2,4,5
- Adolescent marijuana use is associated with impaired learning, memory, and cognition, and some of these disruptions may cause permanent changes.
- Teen marijuana use may cause a lower IQ in adulthood.
- THC exposure in the womb can result in permanent brain damage.
- Teen marijuana use could lead to impaired verbal memory later in life.
- Adolescent marijuana use may alter the reward system in the brain and increase the chance of using other drugs of abuse.
- Increased likelihood of dropping out of school
- Symptoms of chronic bronchitis
- Marijuana addiction
How Marijuana Use Affects Physical Health
Marijuana use can cause many deleterious effects on your physical health, including:2,4
- Inflammation of airways
- Increased chance of respiratory infections
- Increased risk of pneumonia
- Increased risk of heart attack and stroke
- Daily cough and phlegm
- Damage to a developing fetus
Long-term marijuana use can also cause Cannabinoid Hyperemesis Syndrome, which results in repeating the emergence of vomiting, nausea, and dehydration. Sometimes this syndrome is so severe it may require emergency medical treatment.4
Marijuana Use Can Cause Mental Health Problems
Chronic marijuana abuse can cause harmful mental health symptoms, such as:4
- Temporary paranoia
- Temporary hallucinations (seeing or hearing things that aren’t there)
- Exacerbation of symptoms in people with schizophrenia
Marijuana use is also associated with other mental illnesses, such as anxiety, depression, and suicidal ideation among adolescents. However, researchers have not determined direct causation—rather, they’ve established a correlation. It’s unclear whether people use marijuana to self-medicate these pre-existing mental health conditions or if marijuana use causes psychiatric illnesses.4 That said, if someone is predisposed to schizophrenia, chronic marijuana use may increase their risk of developing the mental health condition.2 The presence of addiction and co-occurring mental health conditions is known as a dual diagnosis and requires integrated treatment in order to recover from both.
Marijuana Use is Associated with Lower Life Satisfaction
In addition to causing many harmful effects on your physical and mental health, long-term marijuana use can impact your daily living, quality of life, relationships, and more. Here’s how marijuana impacts your life:4
- More interpersonal and relationship problems
- Lower life satisfaction
- Less academic success
- Less career success
- Increased likelihood of dropping out of school
- Increased injuries and accidents
- Increased job absences
Vaping Can Be Deadly
It is a common misconception that vaping marijuana is safer than other smoking alternatives, such as bongs, joints, or blunts. In fact, an unknown fact about marijuana is that vaping THC-containing products has been associated with severe lung issues in over 1,000 consumers—and in extreme cases, even death.6 People who use marijuana vapes have complained of the following symptoms:6
- Shortness of breath
- Chest pain
The FDA is working with the Centers for Disease Control and Prevention (CDC) to investigate what compound is responsible for significant lung injury. So far, they have yet to identify a single compound. Until they know more information, they are recommending that people avoid vaping marijuana and nicotine products.6
Marijuana’s THC Levels Have Increased Over Time
The amount of THC in marijuana has been steadily rising over the past few decades. In the early 1990s, marijuana contained an average of 4% THC, which is extremely low compared to the THC levels of today. Depending on where you live, what type of marijuana you buy, and whether it’s legal or illegal, marijuana often contains 15% THC—oftentimes, much higher, particularly in oils and resins.7
These increasing THC levels may be responsible for more frequent emergency room visits associated with marijuana use—people seeking emergency care often experience distressing symptoms like psychosis, tremors, and extreme anxiety.7
The higher THC levels as well as the increased popularity of edibles also may be responsible for negative side effects. The effects of marijuana edibles take longer to kick in due to having to digest them first. As such, individuals may eat more than they need without realizing it. Lastly, more potent marijuana may increase the risk of marijuana addiction, especially if you use high doses over an extended period of time.4
Chronic Marijuana Use Can Lead to Addiction
There is a lot of controversy and discussion regarding the addictive potential of marijuana, but evidence indicates that chronic marijuana use and abuse can lead to the development of an addiction. In fact, about 9% of marijuana users develop an addiction to this substance. The rate of marijuana addiction nearly doubles (16.7%) in people who began smoking or consuming marijuana in adolescence. Moreover, the rate of addiction is as high as 50% in those who use marijuana on a daily basis.2
Although dependence and addiction are not synonymous, marijuana dependence often indicates the presence of an addiction. And with long-term use, it’s possible to develop a physiological dependence on cannabis as demonstrated by the following marijuana withdrawal symptoms:2
- Marijuana cravings
- Sleep difficulties
Compared to those who begin using marijuana in adulthood, people who start using marijuana in adolescence are between 2 and 4 times as likely to develop a dependence on the drug within 2 years after initiating use.2
Other Facts About Marijuana You Should Know
In addition to everything we covered in this article, here are some other interesting facts about marijuana you should know:4,8
- Inhaling secondhand smoke from marijuana rarely actually makes you high.
- You aren’t likely to fail a drug test after inhaling secondhand marijuana smoke.
- Serving sizes for marijuana vary considerably, and it can be easy to accidentally ingest far more than you intended to, leading to negative consequences.
- Marijuana use can negatively affect learning, memory, motivation, and attention.
- Heavy marijuana use over many years may lower your IQ.
- Marijuana doesn’t actually enhance your creativity—it simply makes you believe you are more creative.
- Spice and K2 are not fake marijuana drugs—they are synthetic cannabinoids that produce much more intense and severe side effects than marijuana.
- Driving while high doubles the risk of getting into an accident.
- The non-psychoactive ingredient of marijuana, cannabidiol or CBD, is being studied for its potential medical uses.
- Despite controversy, research suggests marijuana is a gateway drug, increasing your risk of using other substances.
- You can’t overdose on marijuana in the traditional sense, but people who have taken high doses may experience intensely unpleasant effects like delusions and hallucinations.
- No medications are currently approved for the treatment of marijuana addiction, but behavioral therapies like motivational incentives can help individuals obtain and maintain abstinence.
- Marijuana is currently legal for recreational use in 20 states, including California, Washington, Oregon, Alaska, Maine, Vermont, and more.
- Centers for Disease Control and Prevention. (2017, May 12). Fast Facts and Fact Sheets.
- Volkow ND, Baler RD, Compton WM, Weiss SRB. Adverse health effects of marijuana use. New England Journal of Medicine 370(23), 2219-2227.
- National Institute on Drug Abuse. (2020). How does marijuana produce its effects?
- National Institute on Drug Abuse. (2019). Marijuana DrugFacts.
- National Institute on Drug Abuse. (2020). What are marijuana’s long-term effects on the brain?
- U.S. Food and Drug Administration. (2019). Vaping Illness Update: FDA Warns Public to Stop Using Tetrahydrocannabinol (THC)-Containing Vaping Products and Any Vaping Products Obtained Off the Street.
- National Institute on Drug Abuse. (n.d.). Marijuana.
- National Institute on Drug Abuse. (2015). 10 Things You Can Learn About Marijuana on the Drugs & Health Blog.
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