Cannabis

Cannabis, which some people call marijuana, refers to the dried leaves, flowers, stems, and seeds of the Cannabis sativa L plant. The plant contains at least 125 different cannabinoids,¹ including delta-9 tetrahydrocannabinol (THC). Delta-9 THC is the most abundant form of THC in the cannabis plant. It has intoxicating effects, meaning it can temporarily alter a person’s mood, thoughts, and perceptions.

The Cannabis sativa L plant also contains non-intoxicating cannabinoid compounds like cannabidiol (CBD). CBD products are marketed for a variety of uses. Cannabis sativa L plants containing very small, non-intoxicating amounts of delta-9 THC, which are also called hemp, are mainly used for textile fiber and for their edible seed oils. Unless mentioned otherwise, the information on this webpage is only about cannabis products containing intoxicating amounts of delta-9 THC.

People commonly use cannabis by smoking dried plant material (“buds” or “herb”) in joints like a cigarette, in blunts—cigars or cigar wrappers that have been partly or completely refilled with cannabis—or in pipes or bongs (water pipes). Dried cannabis can also be vaped using electronic vaporizing devices such as dry herb vaporizers and vape pens.

However, along with the cannabis plant flower, there are many products made from the cannabis plant and new ones are constantly being developed and sold. These include:

• Oils and concentrates. Compounds in cannabis can also be extracted to make oils and concentrates that can be vaped or inhaled with devices that are like e-cigarettes. Smoking or vaporizing highly concentrated oils or extracts, also called wax or shatter, from the cannabis plant is known as dabbing. Dabbing can rapidly deliver large amounts of THC to the body, which increases the risk of negative side effects.
• Edibles. Cannabis can also be mixed or added to foods like baked goods, candies, gummies, and drinks. Edibles typically take longer to show effects. People may use more of a product as a result, increasing the likelihood of serious negative health effects.
• Tinctures. Tinctures are cannabis-infused alcohol or oils consumed in small amounts under the tongue or by adding to foods or drinks. This form of cannabis can also deliver large amounts of THC to the body.
• Lotions and balms. These are products applied directly to the skin.²

Yes. Between 1995 and 2022 the delta-9 THC potency (strength) in illegal cannabis products seized by law enforcement quadrupled from 3.96% to 16.14%. Cannabis flower and concentrates in dispensaries can have THC concentrations of more than 40%.³ Higher THC concentrations have been associated with a greater likelihood of cannabis use progressing to cannabis use disorder, among other health concerns.⁴

Delta-8 THC is another intoxicating cannabinoid found in the cannabis plant. Delta-8 THC products have not been FDA-approved for safe use. Eating large amounts of products containing delta-8-THC has led to medical emergencies, including breathing problems^5,6. There is limited research on the health effects delta-8-THC and other intoxicating cannabinoids and related compounds, including delta-10-THC, THC-O-acetate, THCV, THCP, HHC, HHC-O-acetate, HHCP, and CBN.

Cannabidiol (CBD) is a compound found in the cannabis plant. CBD is marketed as an ingredient in many consumer products, including supplements, foods, oils, and lotions. CBD is not intoxicating like THC.⁷ However, it may have side effects including drowsiness, decreased appetite, vomiting and diarrhea.⁸ Products have been found to contain different amounts of CBD than their labels show, and some products marketed as CBD have been found to contain THC.⁹ Read more about CBD on the U.S. Centers for Disease Control and Prevention (CDC) website.

Synthetic cannabinoids, which are lab-made substances that are chemically similar to compounds found in the cannabis plant, can produce serious negative health effects.¹⁰ These products, which are also known as Spice or K2, may have a much higher concentration of THC and can be much more powerful. Use of synthetic cannabinoids is associated with severe, potentially life-threatening health effects.^11,12

Cannabis may affect people differently depending on: ^13,14,15,16

• The amount taken.
• Potency (concentration of THC).
• A product’s ingredients.
• The way it is ingested.
• Other drugs a person may have taken.
• A person’s underlying medical conditions.
• Age, sex, and genetic differences.
• A person’s experience with cannabis use.

Intoxication

Many people use cannabis to feel intoxicated or “high”.¹⁷ Cannabis can make people feel more happy or relaxed. Cannabis can cause altered time perception, and impaired thinking, memory, and body movement. It can also it can also make people feel more irritable or restless.¹⁸

Anxiety, Fear, Distrust, Panic, or Hallucinations

These effects are more common when a person takes a large amount, the cannabis product is strong (has a high level of THC), or the person has little experience with using cannabis.^19,20,21

Physical Side Effects

Commonly reported symptoms of cannabis use include increased appetite.²² Research shows that cannabis use may help manage symptoms of nausea or vomiting, common side effects of chemotherapy.²³ However, other side effects may include an elevated heart rate and respiratory problems.^20,24

Children eating cannabis edibles, such as gummies, is a growing health concern. This usually happens by accident and can result in hospitalization and serious illness.^25,26 Eating large amounts of products containing delta-8-THC has led to medical emergencies, including among children.^27,28

Harms to Lung Health

The smoke from cannabis products contains many of the same toxins, irritants, and carcinogens as tobacco smoke, and smoking cannabis can also harm lung tissue.^29,30 Long-term cannabis smoking is associated with respiratory issues such as large airway inflammation, increased airway resistance, lung hyperinflation, and chronic bronchitis.^31,32,33 However, more research is needed, as high rates of tobacco use among people who also use cannabis make it hard to distinguish the effects of cannabis alone.^34,33

Mental Health Effects

Cannabis use has been linked to certain mental health conditions. Read more about cannabis use and mental health.

Cardiovascular Effects

Cannabis can increase heart rate and blood pressure right after use. Some research shows an association between long-term cannabis use and an increased risk of stroke, heart attack, and arrythmias.^35,36 However, more research is needed to determine if there is a direct connection between cannabis use and cardiovascular disease, or if other factors are involved.³⁷

Gastrointestinal Problems

These include cannabinoid hyperemesis syndrome (CHS), which is when a person has nausea, vomiting, and abdominal pain after long-term, heavy cannabis use.³⁸ Other potential gastrointestinal issues include acid reflux, pancreatitis, and peptic ulcer disease.³⁹

Increased Cancer Risk

Research has linked the use of cannabis products with an increased likelihood of developing head, neck, or throat cancer,⁴⁰ particularly in people who smoke cannabis.⁴¹

Frequent or heavy cannabis use has been linked to problems in cognitive functions like learning and memory, attention, processing speed, perceptual motor function, and language.^42,43,44,45

Some evidence has linked cannabis use to earlier onset of psychosis in people with genetic risk factors for psychotic disorders, including schizophrenia, as well as worse symptoms in people who already have these conditions. The association between heavy cannabis use and schizophrenia has been found to be especially strong in young males compared to females. Cannabis intoxication can also induce a temporary psychotic episode in some people, especially at high doses. Experiencing such an episode may be linked with developing a psychotic disorder later in life.⁴⁶

Some research has also shown an increased risk of depression in people who use cannabis during adolescence.⁴⁷ Research has also linked cannabis use with suicidal thoughts and behaviors among teens⁴⁸ and military veterans in the United States.^49,50

While people with mental health disorders and related symptoms are more likely to use cannabis,⁵¹ many factors that influence mental health—such as genes, trauma, and stress—also influence how likely someone is to use drugs, including cannabis. Given these related genetic and environmental vulnerabilities, additional data from prospective, longitudinal research (studies that measure participants’ health over long periods of time) are needed to determine whether, to what extent, and for whom cannabis may cause or contribute to poor mental health outcomes.

Cannabinoid hyperemesis syndrome (CHS) is when a person has nausea, vomiting, and abdominal pain after long-term, heavy cannabis use.⁴⁰ It can recur and often requires medical attention. People sometimes try to temporarily relieve their symptoms by taking hot showers or baths. However, CHS only resolves when a person stops using cannabis completely.^52,53

Secondhand smoke from cannabis products has many of the same toxins, irritants, and carcinogens as secondhand tobacco smoke.⁵⁴ In some environments, secondhand cannabis smoke can produce positive cannabis drug test results.⁵⁵ One study in a well-ventilated coffee shop found low levels of THC in the blood of non-smoking bystanders.⁵⁶

Secondhand exposure can also produce positive urine tests.^57,58 This is also true for children. Positive urine tests have been reported in children exposed to secondhand cannabis in their homes or in attached homes,⁵⁹ which can lead to respiratory infections.⁶⁰

The use of cannabis during pregnancy may have harmful effects on a baby’s health after birth. Research has linked it with lower birth weight, preterm birth, hospitalization, death within one year of birth, and other negative outcomes.^61,62  Given the potential of cannabis to negatively impact the developing brain, the American College of Obstetricians and Gynecologists recommends that obstetrician-gynecologists counsel women against using cannabis while trying to get pregnant, during pregnancy, and while they are breastfeeding.

NIDA supports the HEALthy Brain and Child Development (HBCD) Study, which will follow a large population of mothers and their infants from the prenatal period through age 10. This study aims to better understand healthy development and shed light on how early exposure to cannabis and other substances, stressors, and trauma affect brain development and mental health, and how to reduce adverse outcomes.

Chronic, heavy—every day or almost—use of cannabis products with THC is associated with developing cannabis use disorder, a type of substance use disorder. Studies have estimated that 22% to 30% of people who use cannabis have the disorder.^63,64 The strongest predictor of cannabis use disorder is how often someone uses it, but other factors, like a family history of drug use and how long a person has been using cannabis, can also play a role.⁶⁵

The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5)—a reference text published by the American Psychiatric Association that health professionals use to diagnose substance use disorders and other psychiatric disorders—defines cannabis use disorder as a pattern of use that leads to clinically significant impairment or distress. This means a person has had two or more of the following symptoms in a 12-month period:

• Using cannabis in larger amounts or over a longer period than was intended.
• Persistent desire or unsuccessful efforts to cut down or control cannabis use.
• Spending a lot of time getting, using, or recovering from the effects of cannabis.
• Craving, or a strong desire or urge to use cannabis.
• Using cannabis even though it causes problems at work, school, or home.
• Continuing to use cannabis despite social or relationship problems.
• Giving up important hobbies, or activities with friends and family, or in the workplace to use cannabis.
• Using cannabis in situations with risk of injury.
• Continued use despite knowing that ongoing physical or psychological problems have been caused or worsened by cannabis use.
• Cannabis tolerance, which is a need for increased amounts of cannabis to achieve the desired effect.
• Withdrawal symptoms after stopping cannabis use.

Cannabis use disorder can be diagnosed as mild (when a person has two or three of these symptoms), moderate (four or five of these symptoms), or severe (six or more of these symptoms).

A person may have withdrawal symptoms after stopping or significantly decreasing heavy or long-term cannabis use, even if they don’t have cannabis use disorder. One study estimated that 12.1% of people who frequently use cannabis experience cannabis withdrawal.⁶⁶ Withdrawal symptoms may include anger, irritability, aggression, feeling nervous or anxious, restlessness, decreased appetite or weight, depression, insomnia, experiencing strange or unsettling dreams, headaches, sweating, abdominal pain, and tremor. ^65,67

Research shows that behavioral interventions such as cognitive behavioral therapy, motivational enhancement therapy, and contingency management can be effective in treating cannabis use disorder.⁶⁸ Read more about behavioral treatments for substance use disorders on the National Institute of Mental Health website. There are currently no FDA-approved medications for the treatment of cannabis use disorder or for medically assisted withdrawal,⁶⁹ but research is ongoing.

Cannabis products are among the first substances along with alcohol and tobacco that a person will likely encounter in their life (MTF, 2023), and people who use substances commonly use these before trying others. Still, most people who use or have used cannabis do not go on to use other substances later in life.⁷¹

However, risk factors for cannabis use are similar to risk factors for use of other drugs with addiction potential,⁷² and studies have associated use of cannabis with developing cannabis use disorder. Using these products at a younger age in particular increases the likelihood of developing a cannabis use disorder later in life.^73,74 In addition, using cannabis may cause brain changes that can make a person more likely to develop an addiction to other drugs.⁷⁵

Studies have found that using cannabis may affect a person’s ability to drive.⁷⁶  It is the drug most frequently found in the blood of drivers involved in motor vehicle crashes, including fatal ones.⁷⁷ A number of research analyses have found that the risk of being involved in a crash increased after cannabis use.^76,78,79 However, a study conducted by the National Highway Traffic Safety Administration found no significant increased crash risk attributable to cannabis use.⁸⁰

Adolescence is an important period of brain development, and cannabis use may influence the brain in ways that could lead to long-term harmful effects.^81,82 Studies show that regular, heavy cannabis use in adolescence is associated with negative effects on working memory, processing speed,⁸³ verbal memory,⁸⁴  and academic functioning.⁸⁵  It is also associated with negative effects on educational attainment, employment, and income in young adulthood.⁸⁶

Cannabis use at a young age has also been linked to other mental health conditions, including the likelihood of developing psychosis⁸⁷ and to developing cannabis use disorder later in life.

The NIDA-funded Monitoring the Future survey measures drug and alcohol use and related attitudes among adolescent students nationwide. Find recent survey data related to cannabis use here. NIDA supports the Adolescent Brain Cognitive Development^SM Study (ABCD Study^®), which follows nearly 12,000 children ages 9 and 10—before substance use typically begins—into young adulthood.

The ABCD Study^® explores the effects of environmental, social, genetic, and other biological factors on the developing adolescent brain. This study will provide critical insights into risk and resilience factors for cannabis and other substance use to inform future prevention interventions. See ABCD Study^® results on cannabis exposure for more information.

In recent years, adults aged 50 years or older have had the largest increase in cannabis use compared to any other age group, with the greatest increase among those 65 years or older.^88,89 Studies suggest that older adults mainly use cannabis to self-treat chronic conditions such as pain and musculoskeletal disorders, sleep disturbances, anxiety and depression, cancer, glaucoma, Parkinson’s disease, and HIV/AIDS.^90,91,92 

Some research suggests that cannabis use may have different effects on the brain in older adults compared to adolescents or young adults who use cannabis.^93,94 Cannabis may also interact with other medicines older adults may be taking such as warfarin, opioids, and benzodiazepines.^95,96

The U.S. Food and Drug Administration (FDA) has not approved the use of any product containing whole cannabis plant material for any purpose, even though cannabis and cannabinoid products are marketed for various therapeutic uses and are available in many states from medical cannabis dispensaries.

However, the FDA has approved synthetic THC-based medications (dronabinol and nabilone) to treat nausea and vomiting associated with cancer chemotherapy. Dronabinol is also approved to treat anorexia and weight loss associated with HIV/AIDS. The FDA has also approved a plant derived cannabidiol-based medication to treat seizures associated with rare forms of epilepsy.

There is evidence that cannabis can be effective in treating some forms of pain, and there is emerging evidence that it may have additional therapeutic uses. Research will continue to explore potential therapeutic effects of cannabis to help inform individual and public health decisions, including strategies to minimize potential harms associated with cannabis use.

It is important to consult with a doctor before consuming cannabis and cannabinoid products to treat medical conditions. Although research shows that people in the United States increasingly view cannabis use as low risk, it may cause negative health effects and can interact with other drugs a person is taking.⁹⁷

• NIDA funds research on the endocannabinoid system, cannabinoid compounds, and health effects of cannabis to support individual and public health.
• The Institute’s research supports development of new treatments for cannabis use disorder. It also includes research on the factors underlying substance use and substance use disorders, and on developing new ways to prevent substance use disorders.
• NIDA supports epidemiology, policy research and public health outcomes research related to cannabis use, including the Monitoring the Future survey and a medicinal cannabis use registry.
• NIDA also helps support the HEALthy Brain and Child Development (HBCD) Study, the largest long-term study of early brain and child development in the United States. The study will collect information about participants during pregnancy, at birth, and through early childhood. A subset of participants will include babies that were exposed during pregnancy or infancy to cannabis.
• The Adolescent Brain Cognitive Development^SM Study (ABCD Study^®) researches the impacts of cannabis exposure across the lifespan, from the prenatal period through adolescence and young adulthood, and later adulthood.
• NIDA also funds research on potential therapeutic uses of cannabis and cannabinoids to reduce use of other substances, including opioids.