Some people who use marijuana will develop marijuana use disorder, meaning that they are unable to stop using marijuana even though it’s causing health and social problems in their lives.
- One study estimated that approximately 3 in 10 people who use marijuana have marijuana use disorder.
- Another study estimated that people who use cannabis have about a 10% likelihood of becoming addicted.
- The risk of developing marijuana use disorder is greater in people who start using marijuana during youth or adolescence and who use marijuana more frequently.
The following are signs of marijuana use disorder:
- Using more marijuana than intended
- Trying but failing to quit using marijuana
- Spending a lot of time using marijuana
- Craving marijuana
- Using marijuana even though it causes problems at home, school, or
work
- Continuing to use marijuana despite social or relationship problems.
- Giving up important activities with friends and family in favor of using
marijuana.
- Using marijuana in high-risk situations, such as while driving a car.
- Continuing to use marijuana despite physical or psychological
problems.
- Needing to use more marijuana to get the same high.
- Experiencing withdrawal symptoms when stopping marijuana use.
People who have marijuana use disorder may also be at a higher risk of other negative consequences, such as problems with attention, memory, and learning.
Some people who have marijuana use disorder may need to use more and more marijuana or greater concentrations of marijuana over time to experience a “high.” The greater the amount of tetrahydrocannabinol (THC) in marijuana (in other words, the concentration or strength), the stronger the effects the marijuana may have on the brain. The amount of THC in marijuana has increased over the past few decades.
In a study of cannabis research samples over time, the average delta-9 THC (the main form of THC in the cannabis plant) concentration almost doubled, from 9% in 2008 to 17% in 2017. Products from dispensaries often offer much higher concentrations than seen in this study. In a study of products available in online dispensaries in 3 states with legal non-medical adult marijuana use, the average THC concentration was 22%, with a range of 0% to 45%. In addition, some methods of using marijuana (for example, dabbing and vaping concentrates) may deliver very high levels of THC to the user.
Researchers do not yet know the full extent of the consequences when the body and brain are exposed to high concentrations of THC or how recent increases in concentrations affect the risk of someone developing marijuana use disorder.
What is marijuana?
Marijuana refers to the dried leaves, flowers, stems, and seeds from the Cannabis sativa or Cannabis indica plant. The plant contains the mind-altering chemical THC and other similar compounds. Extracts can also be made from the cannabis plant (see "
Marijuana Extracts").
According to the
National Survey on Drug Use and Health, cannabis (marijuana) is one of the most used drugs in the United States, and its use is widespread among young people. In 2021, 35.4% of young adults aged 18 to 25 (11.8 million people) reported using marijuana in the past year. According to the
Monitoring the Future survey, rates of past year marijuana use among middle and high school students have remained relatively steady since the late 1990s. In 2022, 30.7% of 12th graders reported using marijuana in the past year and 6.3% reported using marijuana daily. In addition, many young people also use vaping devices to consume cannabis products. In 2022, nearly 20.6% of 12th graders reported that they
vaped marijuana in the past year and 2.1% reported that they did so daily.
Legalization of marijuana for medical use or adult recreational use in a growing number of states may affect these views.
How do people use marijuana?
People smoke marijuana in hand-rolled cigarettes (joints) or in pipes or water pipes (bongs). They also smoke it in blunts—emptied cigars that have been partly or completely refilled with marijuana. To avoid inhaling smoke, some people are using vaporizers. These devices pull the active ingredients (including THC) from the marijuana and collect their vapor in a storage unit. A person then inhales the vapor, not the smoke. Some vaporizers use a liquid marijuana extract.
People can mix marijuana in food (edibles), such as brownies, cookies, or candy, or brew it as a tea. A newly popular method of use is smoking or eating different forms of THC-rich resins.
Marijuana Extracts
Smoking THC-rich resins extracted from the marijuana plant is on the rise. People call this practice dabbing. These extracts come in various forms, such as:
hash oil or honey oil—a gooey liquid
wax or budder—a soft solid with a texture like lip balm
shatter—a hard, amber-colored solid
These extracts can deliver extremely large amounts of THC to the body, and their use has sent some people to the emergency room. Another danger is in preparing these extracts, which usually involves butane (lighter fluid). A number of people have caused fires and explosions and have been seriously burned from using butane to make extracts at home.
How does marijuana affect the brain?
Marijuana has both short-and long-term effects on the brain.
Short-Term Effects
When a person smokes marijuana, THC quickly passes from the lungs into the bloodstream. The blood carries the chemical to the brain and other organs throughout the body. The body absorbs THC more slowly when the person eats or drinks it. In that case, they generally feel the effects after 30 minutes to 1 hour.
THC acts on specific brain cell receptors that ordinarily react to natural THC-like chemicals. These natural chemicals play a role in normal brain development and function.
Marijuana over activates parts of the brain that contain the highest number of these receptors. This causes the "high" that people feel. Other effects include:
- altered senses (for example, seeing brighter colors)
- altered sense of time
- changes in mood
- impaired body movement
- difficulty with thinking and problem-solving
- impaired memory
- hallucinations (when taken in high doses)
- delusions (when taken in high doses)
- psychosis (risk is highest with regular use of high potency
marijuana)
Long-Term Effects
Marijuana also affects brain development. When people begin using marijuana as teenagers, the drug may impair thinking, memory, and learning functions and affect how the brain builds connections between the areas necessary for these functions. Researchers are still studying how long marijuana's effects last and whether some changes may be permanent.
For example, a study from New Zealand conducted in part by researchers at Duke University showed that people who started smoking marijuana heavily in their teens and had an ongoing marijuana use disorder lost an average of 8 IQ points between ages 13 and 38. The lost mental abilities didn't fully return in those who quit marijuana as adults. Those who started smoking marijuana as adults didn't show notable IQ declines.
In another recent study on twins, those who used marijuana showed a significant decline in general knowledge and in verbal ability (equivalent to 4 IQ points) between the preteen years and early adulthood, but no predictable difference was found between twins when one used marijuana and the other didn't. This suggests that the IQ decline in marijuana users may be caused by something other than marijuana, such as shared familial factors (e.g., genetics, family environment). NIDA’s Adolescent Brain Cognitive Development (ABCD) study, a major longitudinal study, is tracking a large sample of young Americans from late childhood to early adulthood to help clarify how and to what extent marijuana and other substances, alone and in combination, affect adolescent brain development.
A Rise in Marijuana’s THC Levels
The amount of THC in marijuana has been increasing steadily over the past few decades. For a person who's new to marijuana use, this may mean exposure to higher THC levels with a greater chance of a harmful reaction. Higher THC levels may explain the rise in emergency room visits involving marijuana use.
The popularity of edibles also increases the chance of harmful reactions. Edibles take longer to digest and produce a high. Therefore, people may consume more to feel the effects faster, leading to dangerous results.
Higher THC levels may also mean a greater risk for addiction if people are regularly exposing themselves to high doses.
What are the other health effects of marijuana?
Marijuana use may have a wide range of effects, both physical and
mental.
Physical Effects
Breathing problems. Marijuana smoke irritates the lungs, and people who smoke marijuana frequently can have the same breathing problems as those who smoke tobacco. These problems include daily cough and phlegm, more frequent lung illness, and a higher risk of lung infections. Researchers so far haven't found a higher risk for lung cancer in people who smoke marijuana.
Increased heart rate. Marijuana raises heart rate for up to 3 hours after smoking. This effect may increase the chance of heart attack. Older people and those with heart problems may be at higher risk.
Problems with child development during and after pregnancy. One study found that about 20% of pregnant women 24-years-old and younger screened positive for marijuana. However, this study also found that women were about twice as likely to screen positive for marijuana use via a drug test than they state in self-reported measures.
This suggests that self-reported rates of marijuana use in pregnant females is not an accurate measure of marijuana use and may be underreporting their use. Additionally, in one study of dispensaries, nonmedical personnel at marijuana dispensaries were recommending marijuana to pregnant women for nausea, but medical experts warn against it.
This concerns medical experts because marijuana use during pregnancy is linked to lower birth weight and increased risk of both brain and behavioral problems in babies. If a pregnant woman uses marijuana, the drug may affect certain developing parts of the fetus's brain. Children exposed to marijuana in the womb have an increased risk of problems with attention, memory, and problem-solving compared to unexposed children.
Some research also suggests that moderate amounts of THC are excreted into the breast milk of nursing mothers. With regular use, THC can reach amounts in breast milk that could affect the baby's developing brain. Other recent research suggests an increased risk of preterm births.
Intense nausea and vomiting. Regular, long-term marijuana use can lead to some people to develop Cannabinoid Hyperemesis Syndrome. This causes users to experience regular cycles of severe nausea, vomiting, and dehydration, sometimes requiring emergency medical attention.
Reports of Deaths Related to Vaping
The Food and Drug Administration has alerted the public to hundreds of reports of serious lung illnesses associated with vaping, including several deaths. They are working with the Centers for Disease Control and Prevention (CDC) to investigate the cause of these illnesses. Many of the suspect products tested by the states or federal health officials have been identified as vaping products containing THC, the main psychotropic ingredient in marijuana. Some of the patients reported a mixture of THC and nicotine; and some reported vaping nicotine alone. No one substance has been identified in all of the samples tested, and it is unclear if the illnesses are related to one single compound. Until more details are known, FDA officials have warned people not to use any vaping products bought on the street, and they warn against modifying any products purchased in stores. They are also asking people and health professionals to
report any adverse effects. The CDC has posted an
information page for consumers.
Mental Effects
Long-term marijuana use has been linked to mental illness in some people, such as:
- temporary hallucinations
- temporary paranoia
- worsening symptoms in patients with schizophrenia—a severe mental disorder with symptoms such as hallucinations, paranoia, and disorganized thinking
Marijuana use has also been linked to other mental health problems, such as depression, anxiety, and suicidal thoughts among teens. However, study findings have been mixed. children or people with asthma.
How Does Marijuana Affect a Person's Life?
Compared to those who don't use marijuana, those who frequently use large amounts report the following:
more relationship problems
People also report less academic and career success. For example, marijuana use is linked to a higher likelihood of dropping out of school. It's also linked to more job absences, accidents, and injuries.
Is marijuana a gateway drug?
Use of alcohol, tobacco, and marijuana are likely to come before use of other drugs. Animal studies have shown that early exposure to addictive substances, including THC, may change how the brain responds to other drugs. For example, when rodents are repeatedly exposed to THC when they're young, they later show an enhanced response to other addictive substances—such as morphine or nicotine—in the areas of the brain that control reward, and they're more likely to show addiction-like behaviors.
Although these findings support the idea of marijuana as a "gateway drug," the majority of people who use marijuana don't go on to use other "harder" drugs. It's also important to note that other factors besides biological mechanisms, such as a person’s social environment, are also critical in a person’s risk for drug use and addiction.
Can a person overdose on marijuana?
An
overdose occurs when a person uses enough of the drug to produce life-threatening symptoms or death. There are no reports of teens or adults dying from marijuana alone. However, some people who use marijuana can feel some very uncomfortable side effects, especially when using marijuana products with high THC levels. People have reported symptoms such as anxiety and paranoia, and in rare cases, an extreme psychotic reaction (which can include delusions and hallucinations) that can lead them to seek treatment in an emergency room.
While a psychotic reaction can occur following any method of use, emergency room responders have seen an increasing number of cases involving marijuana edibles. Some people (especially preteens and teens) who know very little about edibles don't realize that it takes longer for the body to feel marijuana’s effects when eaten rather than smoked. So they consume more of the edible, trying to get high faster or thinking they haven't taken enough. In addition, some babies and toddlers have been seriously ill after ingesting marijuana or marijuana edibles left around the house.
Is marijuana addictive?
Marijuana use can lead to the development of a substance use disorder, a medical illness in which the person is unable to stop using even though it's causing health and social problems in their life. Severe substance use disorders are also known as addiction. Research suggests that between 9 and 30 percent of those who use marijuana may develop some degree of marijuana use disorder. People who begin using marijuana before age 18 are four to seven times more likely than adults to develop a marijuana use disorder.
Many people who use marijuana long term and are trying to quit report mild withdrawal symptoms that make quitting difficult. These include:
- grouchiness
- sleeplessness
- decreased appetite
- anxiety
- cravings
What treatments are available for marijuana use disorder?
No medications are currently available to treat marijuana use disorder, but behavioral support has been shown to be effective. Examples include therapy and motivational incentives (providing rewards to patients who remain drug-free). Continuing research may lead to new medications that help ease withdrawal symptoms, block the effects of marijuana, and prevent relapse.
Points to Remember
- Marijuana refers to the dried leaves, flowers, stems, and seeds from the Cannabis sativa or Cannabis indica plant.
- The plant contains the mind-altering chemical THC and other related compounds.
- People use marijuana by smoking, eating, drinking, or inhaling it.
- Smoking and vaping THC-rich extracts from the marijuana plant (a practice called dabbing) is on the rise.
- THC overactivates certain brain cell receptors, resulting in effects such as:
- altered senses
- changes in mood
- impaired body movement
- difficulty with thinking and problem-solving
- impaired memory and learning
- Marijuana use can have a wide range of health effects, including:
- hallucinations and paranoia
- breathing problems
- possible harm to a fetus's brain in pregnant women
- The amount of THC in marijuana has been increasing steadily in recent decades, creating more harmful effects in some people.
- It's unlikely that a person will fail a drug test or get high from passive exposure by inhaling secondhand marijuana smoke.
- There aren’t any reports of teens and adults dying from using marijuana alone, but marijuana use can cause some very uncomfortable side effects, such as anxiety and paranoia and, in rare cases, extreme psychotic reactions.
- Marijuana use can lead to a substance use disorder, which can develop into an addiction in severe cases.
- No medications are currently available to treat marijuana use disorder, but behavioral support can be effective.
