Cannabis

Overview

Cannabinoids are a group of substances found in the Cannabis sativa L plant. The main cannabinoids are delta-9 tetrahydrocannabinol (THC) and cannabidiol (CBD). THC is intoxicating and CBD is not.

Cannabis products with substantial THC (“marijuana”) can cause changes in mood, thoughts, and perceptions of reality. They can harm the brain and other parts of the body. The variety of cannabis products, how much THC they have, and the ways people can consume them have increased.

Unless mentioned otherwise, the information on this webpage is about cannabis products with THC.

Definitions

Cannabis refers to the Cannabis sativa L plant. This includes the dried leaves, flowers, stems, and seeds of the cannabis plant. Cannabis also refers to “marijuana,” meaning all plant materials and products with substantial amounts of THC.

Cannabidiol (CBD) is made from hemp, meaning Cannabis sativa L with very little THC. CBD is marketed as an ingredient in many consumer products, including supplements, foods, oils, and lotions. CBD is not intoxicating like THC. However, CBD may have side effects, including decreases in alertness, changes in mood, decreased appetite, and gastrointestinal symptoms such as diarrhea. It has been associated with liver injury, male reproductive harm, and interactions with other drugs.

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. Read more about CBD on the U.S. Centers for Disease Control and Prevention (CDC) website.

Delta-8 THC is another intoxicating cannabinoid found in the cannabis plant in very small amounts.  Delta-8 THC products are made by adding solvents and acids to CBD. Other lab-made intoxicating products made from CBD are also emerging. These products are associated with serious adverse effects and have not been FDA-approved for safe use.

Synthetic cannabinoids are lab-made substances, such as Spice or K2, that are chemically similar to compounds in the cannabis plant. They may have a high concentrations of chemicals similar to THC and be much more powerful than cannabis products. Synthetic cannabinoid use produces intoxication, is associated with severe health problems, and can be life-threatening.

How Do People Use Cannabis?

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 being developed and sold. These include:

• 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 containing cannabis, 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, which are cannabis-infused alcohol or oils that are 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 are applied to the skin.

Effects of Acute Cannabis Use

People use cannabis for many different reasons, including to self-treat chronic health conditions or to feel intoxicated or "high."

Cannabis may affect people different depending on the amount of THC taken, the way it is ingested, other drugs a person may have taken, a person’s underlying medical conditions, age, sex, and genetic differences, and a person’s experience with cannabis use.

Immediate Effects of Cannabis Use

Intoxication

Cannabis can make people feel happier or relaxed, although it can also cause altered time perception and problems with thinking, memory, body movement, and language.

It can also make people feel more irritable or restless. Anxiety, fear, distrust, panic, or hallucinations are more common when a person takes a large amount. This is especially true when the cannabis product has a high level of THC, or when the person has little experience using cannabis.

Effects on Driving

Studies have found that using cannabis may affect a person’s ability to drive. After alcohol, it is the drug most most frequently found in the blood of drivers involved in motor vehicle crashes, including fatal ones. Several research analyses have found that the risk of being involved in a crash increased after cannabis use.

Physical Side Effects

Commonly reported symptoms of cannabis use include increased appetite. Side effects of cannabis and cannabinoids can also include fast heartbeat, low blood pressure, muscle relaxation, bloodshot eyes, slow digestion, dizziness, drowsiness, depression, hallucinations, and paranoia.

Effects of Regular Cannabis Use

Substance Use and Other Mental Disorders

Chronic, heavy — every day or almost every day — use of cannabis products with THC is associated with developing cannabis use disorder. The strongest predictor of cannabis use disorder is how often someone uses it. Other factors, such as a family history of drug use and length of cannabis use, can also play a role. For more information on substance use disorders, visit the page on this topic.

Research has shown an increased risk of depression and suicidal thoughts and behaviors in people who use cannabis regularly. Evidence has also linked cannabis use to earlier onset of psychosis, including schizophrenia, which may be influenced by genetic risk factors for psychotic disorders. Many factors that influence mental health — such as genes, trauma, and stress — also influence how likely someone is to use drugs, including cannabis.

Withdrawal Symptoms

A person may have withdrawal symptoms after stopping or significantly decreasing heavy or long-term cannabis use, even if they do not have cannabis use disorder.

Symptoms of withdrawal from cannabinoids can include being easily annoyed or angered, trouble sleeping, decreased appetite, depression, unsettling dreams, headaches, inability to stay still, hot flashes, shaking hands, nausea, and cramping (rare).

Digestive Health

Long-term cannabis use can lead to cannabis hyperemesis syndrome, a serious cyclical nausea, vomiting, and abdominal pain condition. People sometimes try to temporarily relieve the symptoms by taking hot showers or baths, but these symptoms only resolve when a person stops using cannabis completely. Chronic cannabis use may also cause acid reflux and pancreas and stomach issues.

Lung Health

The smoke from cannabis products contains many of the same toxins, irritants, and carcinogens as tobacco smoke, and smoking cannabis can harm lung tissue. Long-term cannabis smoking is associated with respiratory issues such as large airway inflammation, increased airway resistance, lung hyperinflation, and chronic bronchitis. 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.

Cardiovascular Health

Cannabis can increase heart rate and blood pressure right after use. It can result in dizziness on standing up, which raises danger of fainting and falls.

Long-term cannabis use is associated with an increased risk of stroke, heart attack, and heart arrhythmias. More research is needed to determine if there is a direct connection between cannabis use and cardiovascular disease, or if other factors are involved.

Cancer Risk

Cannabis, especially when smoked, increases risk for head, neck, or throat cancer. Cannabis smoke contains many of the same substances as tobacco smoke, so is likely to affect the lungs. Whether it raises the risk of lung cancer remains unclear.

Secondhand Exposure

Secondhand smoke from cannabis products has many of the same toxins, irritants, and carcinogens as secondhand tobacco smoke. In rare situations, secondhand smoke can produce positive cannabis drug tests.

Other Safety Concerns for Cannabis Use

• There have been reports of contamination of cannabis and cannabinoid products with microorganisms, pesticides, or other substances.
• Some cannabis and cannabinoid products contain amounts of cannabinoids that differ substantially from what is stated on their labels.
• The FDA has warned the public not to use vaping products that contain THC, as products of this type have been implicated in many reported cases of serious lung injuries linked to vaping.

Risk for Certain Populations

Children and Edibles

Children accidentally eating edibles, such as gummies, is a growing health concern. Accidental THC exposure among young children has led to illnesses severe and prolonged enough to require emergency room treatment and hospital admissions.

Effects on Adolescents

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. Studies show that regular, heavy cannabis use in adolescence is associated with negative effects on working memory, processing speed, verbal memory, and academic functioning. It is also associated with negative effects on educational attainment, employment, and income in young adulthood. People who start using cannabis during earlier in life are more likely to develop cannabis use disorder. See the page on Youth and Young Adult Alcohol and Other Substance Use for more information.

Effects During Pregnancy

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. Cannabis can impact the developing brain, so the American College of Obstetricians and Gynecologists recommend against using cannabis while trying to get pregnant, during pregnancy, and while breastfeeding.

Effects on Older Adults

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. Studies show that older adults mainly use cannabis to self-treat chronic physical and mental conditions.

Cannabis use is associated with an increased risk of injury among older adults. Cannabis may also interact with other medicines older adults may be taking, such as warfarin, opioids, and benzodiazepines.

Treatment And Management

Cannabis and Cannabinoids to Treat Medical Conditions

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.

The FDA has not approved the cannabis plant for any medical use. However, the FDA has approved several drugs that contain individual cannabinoids:

• Epidiolex contains a purified form of CBD derived from cannabis and was approved for the treatment of seizures associated with Lennox-Gastaut syndrome or Dravet syndrome, two rare and severe forms of epilepsy.
• Marinol and Syndros contain dronabinol (synthetic THC).
• Cesamet contains nabilone (a synthetic substance similar to THC).
• Dronabinol and nabilone are used to treat nausea and vomiting caused by cancer chemotherapy.
• Dronabinol is also used to treat loss of appetite and weight loss in people with HIV/AIDS.

Treating Cannabis Use Disorder

Research shows that psychosocial treatments such as cognitive behavioral therapy, motivational enhancement therapy, and contingency management can be effective in treating cannabis use disorder. There are currently no FDA-approved medicines for the treatment of cannabis use disorder or for medically assisted withdrawal, but research is ongoing. For more information, visit the Substance Use Disorders page.

Find Clinical Trials

Clinical trials uncover better ways to prevent, diagnose, treat, and understand diseases and conditions. To ensure results apply to everyone, volunteers of all ages, sexes, and backgrounds, including both healthy individuals and those with specific medical conditions, are needed. Find clinical trials on cannabis.

Find Treatment

Find treatment for substance use disorders at FindTreatment.gov or call 1-800-662-HELP (4357), or TTY: 1-800-487-4889.

Community Support

• The Food and Drug Administration (FDA) regulates drugs and medical devices to ensure that they are safe and effective.
  • Learn more about the regulation of products containing cannabis or cannabis-derived compounds from the FDA.
• The Federal Trade Commission (FTC) enforces consumer protection laws.
• Read more about cannabis on the Centers for Disease Control and Prevention website.
• Find information and statistics on drug-impaired driving from the National Highway Traffic Safety Administration.

Note: This resource list is for informational purposes only. It is not comprehensive, and an organization’s inclusion does not constitute an endorsement by NIH.  

Research Information

The National Institutes of Health (NIH) is the largest public funder of biomedical research in the world. NIH invests most of its budget in medical research seeking to enhance life and to reduce illness and disability. NIH-funded research has led to breakthroughs and new treatments helping people live longer, healthier lives, and building the research foundation that drives discovery.  

NIH funds research on the health effects of cannabis and cannabinoid products, including impacts on the developing brain and on mental health. It also supports research on prevention and treatments for cannabis use disorder, the potential therapeutic uses of cannabis, and the public health impacts of cannabis.

NIH is studying the potential use of cannabis as a treatment option for the following:

• Pain relief
• Epilepsy
• Anxiety and post-traumatic stress disorder
• Nausea and vomiting related to cancer treatments
• Multiple sclerosis
• Disordered Sleep

Find NIH-funded research projects using NIH RePORTER, a searchable database of current and past research projects supported by NIH and other federal agencies.