Key points

• Cannabis use may have a wide range of health effects on the body and brain.
• There are several risk factors and negative health outcomes associated with cannabis use.

How cannabis can affect your health

Cannabis is the most commonly used federally illegal drug in the United States, with an estimated 61.9 million people using it in 2022. Cannabis use may have a wide range of health effects on the body and brain.

Cannabis, which can also be called marijuana, weed, pot, or bud, refers to the dried flowers, leaves, stems, and seeds of the cannabis plant. The cannabis plant contains more than 100 compounds (or cannabinoids). These compounds include tetrahydrocannabinol (THC), which is impairing or mind-altering, as well as other active compounds, such as cannabidiol (CBD). CBD – by itself - is not impairing, meaning it does not cause a "high".

Types

Cannabis can be used in a number of ways.

The most common ways include:

• Smoked in joints (like a cigarette), in blunts (cigars or cigar wrappers that have been partly or completely refilled with cannabis) or in bongs (pipes or water pipes)
• Vaped using electronic vaporizing devices (like vape pens) or other vaporizers
• Mixed or infused into foods or drinks (called edibles) like cookies, cakes, or brownies, or tea, cola, or alcohol

Additionally, some people inhale the oil concentrates and other extracts from the cannabis plant—this is known as dabbing. THC oils and concentrates used in vaping and dabbing often involve using highly concentrated forms of THC and may contain additives or be contaminated with other substances that may be harmful.

How cannabis affects a person depends on several factors, including:

• Concentration of THC used
• Frequency of cannabis use
• Use of cannabis with other substances (e.g., alcohol or other drugs), which could increase risk of harm
• Mode of cannabis use (e.g., consuming edibles or products with high THC concentration can have delayed or unpredictable effects and increases the risk of overdose or poisoning)
• Previous experience with cannabis or other drugs
• Biology (e.g., genes, DNA)
• Sex (e.g., women may experience more dizziness after using cannabis compared to men)

Cannabis as medicine

The Food and Drug Administration (FDA) has approved one plant-based cannabis drug called Epidiolex, which contains a purified form of CBD. The prescription medication is approved for treating seizures associated with two rare and severe forms of epilepsy (Lennox-Gastaut syndrome and Dravet syndrome) as well as seizures associated with a rare genetic disorder called tuberous sclerosis complex.

The FDA has also approved two medicines (dronabinol [brand names: Marinol and Syndros] and nabilone [brand name: Cesamet]) that are made from a synthetic or lab-made chemical that mimics THC. These medicines are used to treat nausea in patients with cancer who are having chemotherapy treatment, and to increase appetite in individuals with AIDS who do not feel like eating (wasting syndrome).

These approved products are only available with a prescription from a licensed healthcare provider. There are currently no other FDA-approved uses for cannabis or its derivatives.

There are health risks associated with using cannabis regardless of how it is used. These include:

Cannabis Use Disorder

People who use cannabis can struggle with physical dependency and controlling their use. This is concerning as there is evidence suggesting the use of highly concentrated THC products is associated with more severe cannabis use disorder symptoms. While approximately 3 in 10 persons who report cannabis have a cannabis use disorder, this figure is rising. Some signs and symptoms of cannabis use disorder include trying but failing to quit using cannabis or giving up important activities with friends and family in favor of using cannabis. The risk of developing cannabis use disorder is stronger in people who start using cannabis during youth or adolescence and who use cannabis more frequently.

Brain Health

Cannabis use directly affects brain function—specifically the parts of the brain responsible for memory, learning, attention, decision making, coordination, emotions, and reaction time.

Heart Health

Cannabis can make the heart beat faster and raise blood pressure immediately after use. It could also lead to increased risk of stroke, heart disease, and other vascular diseases.

Driving

Cannabis, like alcohol, negatively affects several skills required for safe driving. You can choose not to drive—and remind your friends and family to do the same—after using cannabis.

• It can slow reaction time and ability to make decisions.
• Cannabis can impair coordination and distort perception.
• The use of multiple substances (such as cannabis and alcohol) at the same time can increase impairment.
• Some studies have shown an association between cannabis use and car crashes; however, more research is needed.

Lung Health

Smoked cannabis, regardless of how it is smoked, can harm lung tissues and cause scarring and damage to small blood vessels.

Mental Health

Cannabis use has been linked to social anxiety, depression, and schizophrenia (a type of mental illness where people might see or hear things that aren't really there), but scientists don't yet fully understand the relationships between these mental health disorders and cannabis use.

Unintentional Poisoning

Edibles, or food and drink products infused with cannabis, have some different risks than smoked cannabis, including a greater risk of poisoning. 7 Some cannabis edibles have packaging designed to mimic the appearance of well-known branded snacks and candy that appeal to children, which increases the risk for unintentional ingestion. Children who consume THC-containing products can become very sick.

Fast Statistics

• Approximately 3 in 10 people who use cannabis have cannabis use disorder.
• It is estimated that people who use cannabis have about a 10% likelihood of becoming addicted.
• The risk of developing cannabis use disorder is greater in people who start using cannabis during youth or adolescence and who use cannabis more frequently.

The following are signs of cannabis use disorder:

• Using more cannabis than intended
• Trying but failing to quit using cannabis
• Spending a lot of time using cannabis
• Craving cannabis
• Using cannabis even though it causes problems at home, school, or work
• Continuing to use cannabis despite social or relationship problems
• Giving up important activities with friends and family in favor of using cannabis
• Using cannabis in high-risk situations, such as while driving a car
• Continuing to use cannabis despite physical or psychological problems
• Needing to use more cannabis to get the same high

People who have cannabis use disorder may also be at a higher risk of other negative consequences, such as problems with attention, memory, and learning.

Cannabis use disorder and increased THC concentration

Some people who have cannabis use disorder may need to use more and more cannabis or greater concentrations of cannabis over time to experience a "high." The greater the amount of tetrahydrocannabinol (THC) in cannabis (in other words, the concentration or strength), the stronger the effects the cannabis may have on the brain. The amount of THC in cannabis has increased over the past few decades.Products with high concentrations of THC can have greater intoxicating effects and increase the risk of overconsumption.

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 cannabis use, the average THC concentration was 22%, with a range of 0% to 45%. In addition, some methods of using cannabis (for example, dabbing and vaping concentrates) may deliver very high levels of THC to the user. 610 Cannabis concentrates come in many different forms and may be called extract, butane hash oil, wax, shatter, butane honey oil (BHO), budder, taffy, and live resin.

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 cannabis use disorder. There is moderate evidence that high THC concentration cannabis use by adolescents and young adults is associated with continued use and development of future mental health symptoms and disorders.

Key points

• Cannabis affects brain development.
• Cannabis use directly affects brain function — specifically the parts of the brain responsible for memory, learning, attention, decision-making, coordination, emotions, and reaction time.

Short and long-term effects of cannabis use on the brain

What are the short-term effects of cannabis use on the brain?

Recent cannabis use (defined as within 24 hours) in youth and adults has an immediate impact on thinking, attention, memory, coordination, movement, and time perception.

What are the long-term effects of cannabis use on the brain?

Cannabis affects brain development. Developing brains, such as those in babies, children, and teenagers, are especially susceptible to the harmful effects of cannabis and tetrahydrocannabinol (THC) because the brain is continuing to develop until around age 25. Although scientists are still learning about the effects of cannabis on developing brains, studies suggest that cannabis use by mothers during pregnancy could be linked to problems with attention, memory, problem-solving skills, and behavior in their children.

Using cannabis before age 18 may affect how the brain builds connections for functions like attention, memory, and learning. Cannabis's effects on attention, memory, and learning may last a long time or even be permanent, but more research is needed to fully understand these effects.

Youth who use cannabis may not do as well in school and may have trouble remembering things.

Factors that determine impact

The impact of cannabis use on the brain depends on many factors, including:

• Amount of tetrahydrocannabinol (THC) in cannabis (in other words, the concentration or strength),
• How often it is used,
• Age of first use, and
• Whether other substances (for example, tobacco and alcohol) are used at the same time.

Long-term impacts on the brain may also be caused by something other than cannabis, such as genetics, the home environment, or other unknown factors. 12 The National Institute on Drug Abuse is conducting a large long-term study (the Adolescent Brain Cognitive Development study, or ABCD study) to better understand the role cannabis and other substances play in adolescent brain development.

Key points

• Cannabis and individual cannabinoids (compounds in the plant like tetrahydrocannabinol [THC] or cannabidiol [CBD]) have been studied to manage the side effects of cancer and cancer therapies (like chemotherapy).
• Findings suggest that certain cannabinoids can help relieve some side effects.

Cannabis use and cancer

Cannabis and individual cannabinoids (compounds in the plant like tetrahydrocannabinol [THC] or cannabidiol [CBD]) have been studied to manage the side effects of cancer and cancer therapies (like chemotherapy). Findings suggest that certain cannabinoids can help relieve some of those side effects. However, studies have not shown that cannabis or individual cannabinoids can cure cancer. Like many other drugs, cannabis can cause side effects and complications. Avoiding or delaying conventional medical care for cancer or relying on cannabis alone to treat or manage the effects of cancer may have serious health consequences.

Frequently Asked Questions

How can cannabis affect symptoms or side effects of cancer or cancer therapy?

Studies of the chemicals (or cannabinoids) found in the cannabis plant suggest that certain cannabinoids can be helpful in treating nausea and vomiting from cancer chemotherapy,as well as in treating neuropathic pain (pain caused by damaged nerves). The U.S Food and Drug Administration (FDA) has approved two specific drugs (dronabinol [name brands Marinol and Syndros] and nabilone [name brand Cesamet]) that are synthetic (man-made) forms of specific cannabinoids for use in cancer patients with chemotherapy-associated nausea and vomiting. More research is needed to understand the effects of cannabis as a treatment for cancer-related symptoms or side effects of cancer therapy.

Is there a link between cannabis and cancer?

Smoked cannabis delivers THC and other cannabinoids to the body, but it also delivers harmful substances, including many of the same toxins and carcinogens (cancer-causing chemicals) found in tobacco smoke, which are harmful to the lungs and cardiovascular system. 4 More research is needed to understand the effects cannabis might have on lung and other respiratory cancers. However, limited evidence of an association between current, frequent, or chronic cannabis smoking and testicular cancer (non-seminoma-type) has been documented.

Because cannabis can be used in different ways, with different levels of active compounds, it can affect each person differently. More research is needed to understand the full impact of cannabis use on cancer.

Key points

• Driving under the influence (DUI) laws are not just for alcohol. Driving under the influence of drugs, including cannabis, is also dangerous and illegal.
• Driving is a complex task that requires your full attention to stay safe and alert.

What you need to know about cannabis use and driving

Cannabis affects areas of the brain that control your body's movements, balance, coordination, memory, and judgment. Cannabis use can impair important skills required for safe driving by:

• slowing your reaction time and ability to make decisions,
• impairing coordination, and
• distorting perception.

Studies have shown an association between acute cannabis use and car crashes, but more research is needed. It is difficult to connect the presence of cannabis or concentration of tetrahydrocannabinol (THC), the compound responsible for cannabis's psychoactive properties (the "high"), to impairment in driving performance for an individual person. Studies have shown that the use of multiple substances (such as cannabis and alcohol) at the same time can increase impairment.

Fast facts

• Cannabis is the most commonly used drug that is illegal at the federal level in the United States.
• In 2021, an estimated 52.5 million people used cannabis in the past year.
• After alcohol, cannabis is the substance most often associated with impaired driving.
• In 2017, about 1 in 8 high school drivers reported driving after using cannabis at least once during the past month.

What you can do to prevent impaired driving

If you intend to drive, the safest option is not to use any alcohol or drugs, including cannabis. Here are steps you can take to help prevent impaired driving if you plan to use, are using, or have used alcohol or drugs, including cannabis:

• Choose not to drive and remind your friends and family to do the same.
• Assign a trusted designated driver who will not drink or use drugs when you are going out with a group of people you know.
• Plan on getting a ride home from someone who has not been drinking alcohol and/or using drugs, using a rideshare service, or calling a taxi.

Key points

• Cannabis can make the heart beat faster and can raise blood pressure immediately after use.
• More research is needed to understand the full impact of cannabis use on the cardiovascular system to determine if cannabis use leads to higher risk of death.

Cannabis use and heart health

Cannabis can make the heart beat faster and can raise blood pressure immediately after use. It could also increase risk of stroke, heart disease, and other vascular diseases. Most of the scientific studies linking cannabis to heart attacks and strokes are based on reports from people who smoked cannabis (as opposed to other methods of administration). Cannabis smoke contains many of the same substances researchers have found in tobacco smoke, which are harmful to the lungs and cardiovascular system.

It is hard to separate the effects of cannabis chemicals like tetrahydrocannabinol (THC) and other cannabinoids on the cardiovascular system from those caused by the irritants and other chemicals present in the smoke. More research is needed to understand the full impact of cannabis use on the cardiovascular system to determine if cannabis use leads to higher risk of death.

Key points

• Smoked cannabis, regardless of how it is smoked, can harm lung tissues and cause scarring and damage to small blood vessels.
• More research is needed to understand the specific effects cannabis smoking may have on lung cancer and other respiratory diseases.

Lung health and smoking cannabis

In general, cannabis is smoked using:

• joints (hand-rolled cigarettes),
• bongs (pipes or water pipes),
• bowls, or
• blunts (cigars or cigar wrappers that have been partly or completely refilled with cannabis).

Smoked cannabis, regardless of how it is smoked, can harm lung tissues and cause scarring and damage to small blood vessels.

Smoke from cannabis has many of the same toxins, irritants, and carcinogens (cancer-causing chemicals) as tobacco smoke. Smoking cannabis can also lead to a greater risk of bronchitis, cough, and mucus production, though these symptoms generally improve when people who smoke cannabis quit.

More research is needed to understand the specific effects cannabis smoking may have on lung cancer and other respiratory diseases like emphysema (lung condition that causes shortness of breath) and chronic obstructive pulmonary disease (COPD).

Cannabis use can cause disorientation and sometimes unpleasant thoughts or feelings of anxiety and paranoia.

People who use cannabis are more likely to develop psychosis (not knowing what is real, hallucinations, and paranoia) and long-lasting mental disorders, including schizophrenia (a type of mental illness where people might hear or see things that are not really there). The association between cannabis and schizophrenia is stronger in people who start using cannabis at an earlier age and use cannabis more frequently.

Cannabis use is also associated with depression; social anxiety; and thoughts of suicide, suicide attempts, and suicide.

Key points

• There is limited evidence that cannabis works to treat most types of acute or chronic pain.
• More research is needed to know whether cannabis works better than other options to manage pain.

Cannabis and pain

Even though pain management is one of the most common reasons people report for using medical cannabis in the United States, there is limited evidence that cannabis works to treat most type of acute or chronic pain.

A few studies have found that cannabis can be helpful in treating neuropathic pain (a specific type of chronic pain caused by damaged nerves). However, more research is needed to know whether cannabis works better than other options to manage pain.

Key points

• Edibles, or food and drink products infused with cannabis, have some different risks than smoked cannabis.
• The amount of tetrahydrocannabinol (THC), or the concentration or strength, is difficult to measure and often unknown or inaccurate as labeled on edible products.

Effects of edible cannabis

Edibles, or food and drink products infused with cannabis, have some different risks than smoked cannabis, including a greater risk of poisoning. Unlike smoked cannabis, edibles can:

• Take from 30 minutes to 2 hours to feel intoxicating effects, so some people may eat too much, which can lead to poisoning and/or serious injury.
• Cause intoxicating effects that last longer than expected, depending on the amount ingested, whether they are eaten on an empty stomach, medications or alcohol used at the same time, and other factors.
• Be unpredictable. The amount of tetrahydrocannabinol (THC), or the concentration or strength, is difficult to measure and often unknown or inaccurate as labeled on edible products. Many people who use edibles can be caught off-guard by their strength and long-lasting effects.

Some cannabis edibles have packaging designed to mimic the appearance of well-known branded snacks and candy that appeal to children. Children who consume THC-containing products can become very sick. They may have problems walking or sitting up or may have a hard time breathing. Since adult cannabis use has been legalized in some states, unintentional cannabis poisonings in children have increased, sometimes requiring visits to the emergency room or hospitalization.

Key points

• Cannabis may be bad for your baby no matter how you use it—this includes smoking, vaping, dabbing, eating or drinking, and applying creams or lotions to the skin.
• If you are using cannabis and are pregnant, planning to become pregnant, or are breastfeeding, talk to your doctor.

Potential health effects of using cannabis during pregnancy

Using cannabis during pregnancy may affect your baby's development and put you at risk of pregnancy complications.

Cannabis use during pregnancy can be harmful to your baby's health. The chemicals in cannabis (in particular, tetrahydrocannabinol or THC) pass through your system to your baby and may harm your baby's development.

Although more research is needed to better understand how cannabis may affect you and your baby during pregnancy, it is recommended that pregnant persons do not use cannabis.

• Some research shows that using cannabis while you are pregnant can cause health problems in newborns, including lower birth weight and abnormal neurological development.
• Breathing cannabis smoke contains many of the toxic and cancer-causing chemicals found in tobacco smoke. THC, the psychoactive or mind-altering compound in cannabis, may also be passed to infants through secondhand smoke.
• The potential health effects of using cannabidiol (CBD) products during pregnancy are currently unknown.

Cannabis use while pregnant and breastfeeding

Can using cannabis during my pregnancy affect my baby's development after birth?

Although scientists are still learning about the effects of cannabis on developing brains, studies suggest that cannabis use by persons during pregnancy could be linked to problems with attention, memory, problem-solving skills, and behavior in their children later in life.

Does using cannabis affect breastfeeding?

The health effects of a breastfeeding person's use of cannabis on their infant or baby are not yet fully known. We do know that chemicals from cannabis can be passed to a baby through breastmilk. THC is stored in body fat and is slowly released over time, meaning a baby could still be exposed even after a person has stopped using cannabis. Thus, persons who are breastfeeding are encouraged to avoid all cannabis use.

Key points

• People of any age, sex, or economic status can develop a substance use disorder for cannabis or other drugs.
• There is limited evidence suggesting that using cannabis increases the risk of using other drugs.

What is known about the risk of using other drugs

Researchers disagree on whether cannabis is a "gateway drug" — the idea that cannabis use leads a person to use other more dangerous drugs, like cocaine or heroin. However, there is limited evidence suggesting that using cannabis increases the risk of using other drugs.

Most people who use cannabis do not go on to use other, "harder" drugs. People who use cannabis and do go on to use other drugs (including alcohol and tobacco) may have a higher risk of dependence or addiction to those drugs, especially if they started using cannabis at an early age and use it frequently.

People of any age, sex, or economic status can develop a substance use disorder for cannabis or other drugs. The following things can affect the likelihood of developing a substance use disorder:

• Family history
• Having another mental health illness (such as anxiety or depression)
• Having peers with substance use disorder
• Loneliness or social isolation
• Lack of family involvement
• Drug availability
• Socioeconomic status

Key points

• Secondhand cannabis smoke contains many of the same toxic and cancer-causing chemicals found in tobacco smoke and some in higher amounts.
• Secondhand cannabis smoke also contains tetrahydrocannabinol (THC), the compound responsible for most of cannabis's psychoactive effects (or the "high").

Exposure to cannabis smoke

The known risks of secondhand exposure to tobacco smoke—including risks to the heart and lungs—raise questions about whether secondhand exposure to cannabis smoke causes similar health risks. Secondhand cannabis smoke contains many of the same toxic and cancer-causing chemicals found in tobacco smoke and some in higher amounts.

Secondhand cannabis smoke also contains tetrahydrocannabinol (THC), the compound responsible for most of cannabis's psychoactive effects (or the "high"). THC can be passed to infants and children through secondhand smoke, and people exposed to secondhand cannabis smoke can experience psychoactive effects, such as feeling high. Recent studies have found strong associations between reports of having someone in the home who uses cannabis (e.g., a parent, relative, or caretaker) and the child having detectable levels of THC. Children exposed to THC are potentially at risk for negative health effects. More research is needed to understand how secondhand cannabis exposure may affect children. Other research shows that cannabis use during adolescence can impact the developing teenage brain and cause problems with attention, motivation, and memory.

More research about the effects of cannabis secondhand smoke is still needed.

Key points

• In 2022, 30.7% of 12^th graders reported using cannabis in the past year, and 6.3% reported using cannabis daily in the past 30 days.
• Cannabis use can have permanent effects on the developing brain when use begins in adolescence, especially with regular or heavy use.

What you need to know about cannabis use and teens

The teen years are a time of growth, exploration, and risk-taking. Some risk-taking may foster identity development and independence (e.g., running for student council, asking someone out on a date). However, some risk behaviors—such as using cannabis—can have adverse effects on a teen's health and well-being.

How many teens use cannabis?

In 2022, 30.7% of US high school 12th graders reported using cannabis in the past year, and 6.3% reported using cannabis daily in the past 30 days. Past-year vaping of cannabis declined from 2020 to 2021 and remained steady in 2022 following large increases in 2018 and 2019. However, many middle and high school students still reported past-year cannabis vaping in 2022—6% of eighth graders, 15% of 10th graders, and 21% of 12th graders.

Cannabis and the teen brain

The teen brain is actively developing and continues to develop until around age 25. Cannabis use during adolescence and young adulthood may harm the developing brain.

Compared with teens who do not use cannabis, teens who use cannabis are more likely to quit high school or not get a college degree.

Negative effects of teen cannabis use

Negative effects include:

• Difficulty thinking and problem-solving
• Problems with memory and learning
• Reduced coordination
• Difficulty maintaining attention
• Problems with school and social life

How can cannabis impact a teen's life:

• Increased risk of mental health issues. Cannabis use has been linked to a range of mental health problems, such as depression and social anxiety. People who use cannabis are more likely to develop temporary psychosis (not knowing what is real, hallucinations, and paranoia) and long-lasting mental disorders, including schizophrenia (a type of mental illness where people might see or hear things that aren't there). The association between cannabis and schizophrenia is stronger in people who start using cannabis at an earlier age and use cannabis more frequently.
• Impaired driving. Driving while impaired by any substance, including cannabis, is dangerous and illegal. Cannabis negatively affects several skills required for safe driving, such as reaction time, coordination, and concentration.
• Potential for addiction. Approximately 3 in 10 people who use cannabis have cannabis use disorder. Some signs and symptoms of cannabis use disorder include trying but failing to quit using cannabis or giving up important activities with friends and family in favor of using cannabis. The risk of developing cannabis use disorder is stronger in people who start using cannabis during youth or adolescence and who use cannabis more frequently.

How can you educate yourself and others?

What teens can do

• Learn the facts about cannabis use so that you can make informed decisions.
• Share information that you learn with friends, parents/guardians, teachers, and others.
• Choose not to drive if you are planning to use, are using, or have used cannabis.

What parents can do

• Talk with your children about the risks of using cannabis while their brains are still developing. Ask your children questions about their cannabis use.
• Know the facts about cannabis. People that begin using cannabis in their teens are more likely to have lasting brain developmental effects and a higher potential for cannabis use disorder.