Frequently Asked Questions

Below you will find answers to some of the commonly asked questions about marijuana.

Marijuana FAQs

Marijuana—which can also be called cannabis, weed, pot, or dope—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 is not impairing, meaning it does not cause a “high”.1

Marijuana is different from cannabidiol (CBD). Marijuana refers to the dried flowers, leaves, stems, and seeds of the cannabis plant. CBD is one of the many compounds, along with THC (tetrahydrocannabinol), that can be present in the cannabis plant. CBD does not cause a “high” by itself. CBD can be derived from hemp, which is defined as any part of a cannabis sativa plant with no more than 0.3% of THC, or non-hemp plants.

In 2018, the U.S. Congress passed and signed into law the Agriculture Improvement Actexternal icon.2 This law removed hemp from the federal Controlled Substances Act, effectively legalizing CBD if it comes from hemp.

However, a few states have not removed hemp from their state’s controlled substances acts, so legality of CBD products differs across states.

Scientists are still learning about how CBD affects the body. The U.S. Food and Drug Administration (FDA)external icon approved Epidiolex, a medicine that contains purified CBD from cannabis plants, to help treat seizure disorders. The FDA has concluded that this drug is safe and effective for the intended use. However, other marketed uses of CBD may not be FDA approved.

Marijuana can be used in a number of ways.3,4 Marijuana can be smoked in joints (like a cigarette), in blunts (cigars or cigar wrappers that have been partly or completely refilled with marijuana), or in bongs (pipes or water pipes). Marijuana also can be mixed or infused into foods like cookies, cakes, or brownies (called edibles) and can be infused in drinks.

It can be vaped using electronic vaporizing devices (i.e., e-cigarettes or vape pens) or other vaporizers. Compounds (or cannabinoids) in marijuana can also be extracted to make oils and concentrates that can be vaped or inhaled. Smoking oils, concentrates, and extracts from the marijuana plant, known as “dabbing,” is on the rise. Health and safety risks exist for each of the different ways of using marijuana.

Marijuana products that contain tetrahydrocannabinol (THC) can have health risks regardless of how they are used because THC is impairing and can affect memory, attention, decision-making, and risk-taking.1

Health and safety risks exist for each of the different ways of consuming marijuana, and scientists do not have enough evidence to say that consuming marijuana in one way is safer than another. For example, smoking marijuana can expose you and those around you to harmful chemicals.5

Oils and concentrates used in vaping and dabbing (which is a specific method of inhaling THC concentrates) often have highly concentrated forms of THC and may contain additives or be contaminated with other substances.6 The effects of using these more concentrated forms of THC are not well understood but may include higher risk of developing cannabis use disorder.1,7 Vaping has also been linked to lung injury.

Marijuana and E-cigarette, or Vaping Use-Associated with Lung Injury (EVALI)

In 2019, a national outbreak of lung injury associated with vaping occurred. Data from patient reports and product testing showed tetrahydrocannabinol (THC)-containing vaping products that also contained vitamin E acetate were linked to most cases. This outbreak resulted in over 2,800 emergency department visits and 68 confirmed deaths. More information about the outbreak can be found here.

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

  • Previous experience with marijuana or other drugs
  • Biology (e.g., genes)
  • Sex (e.g., women may experience more dizziness after using marijuana compared to men9)
  • How the drug is taken (e.g., consuming edibles or products with high tetrahydrocannabinol [THC] concentration can have delayed or unpredictable effects and increases the risk of overdose or poisoning1)
  • How much of the drug is used
  • How often it is used
  • If it is used in combination with other substances (using marijuana with alcohol or other drugs could lead to increased risk of harm, especially with unknown drug-to-drug interactions1)

The marijuana plant has compounds that may help symptoms for some health problems.1 While more states are making it legal to use the plant as medicine for certain conditions, scientists are still learning the ways that marijuana may help or harm people. For example, smoked marijuana may damage your lungs and respiratory system.1

Certain compounds in marijuana products may affect your brain or body in harmful ways. In addition, no federal standards have been implemented for the quality and safety of marijuana products sold in state-based medical marijuana dispensaries. These products are not approved by the FDA.

Research on the medical use of marijuana is still in early stages, and much remains unknown about the plant and how it interacts with the body. Currently, the FDA has approved one plant-based marijuana drug (Epidiolex), which contains purified cannabidiol (CBD) from the marijuana plant. The drug 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 tuberous sclerosis complex, a rare genetic disorder that causes benign tumors to form in many parts of the body.

The FDA has also approved two medicines (dronabinol [brand names: Marinol and Syndros] and nabilone [brand name: Cesamet]) made from a synthetic or lab-made chemical that mimics tetrahydrocannabinol (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).

Yes. Research suggests that 3 in 10 people who use marijuana may have some form of marijuana use disorder,10 meaning they are unable to stop using marijuana even though it is causing health and social problems in their lives.11,12 For people who begin using marijuana before the age of 18 and who use marijuana often (daily/near daily), the risk of developing marijuana use disorder is even greater.12

In addition, the concentration or strength of tetrahydrocannabinol (THC) in marijuana products is increasing,6,13 and daily or near daily use of marijuana is increasing,14 both of which could make addiction and other health consequences more likely.

For more information visit CDC’s section on addiction or the National Institute on Drug Abuse’s pages on addiction scienceexternal icon and marijuanaexternal icon.

The signs that someone might have marijuana use disorder15 are:

  • Using more marijuana than intended
  • Trying but failing to quit using marijuana
  • Spending a lot of time using marijuana
  • Craving marijuana
  • Using marijuana even when 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 driving a car
  • Continuing to use marijuana despite physical or psychological problems
  • Needing to use more marijuana to get the same high
  • Experiencing symptoms when stopping marijuana use

People with marijuana use disorder, compared to those who use marijuana but do not have marijuana use disorder, are at a greater risk for negative consequences, such as problems with attention, memory, and learning. Please visit the National Institute on Drug Abuse to learn more about addictionexternal icon and available treatmentsexternal icon.

For more on the health risks and effects of marijuana, visit CDC’s web page on marijuana and health effects.

While a fatal overdose caused solely by marijuana is unlikely, marijuana is not harmless. The signs of using too much marijuana are similar to the typical effects of using marijuana but more severe. These signs may include:

  • extreme confusion
  • anxiety
  • paranoia
  • panic
  • fast heart rate
  • delusions or hallucinations
  • increased blood pressure
  • severe nausea or vomiting

In some cases, these effects can lead to unintentional injury, such as a motor vehicle crash, fall, or poisoning. Overconsumption of marijuana can happen especially when using marijuana-infused products like edibles and beverages, since it can take up to 2 hours to feel the effects from the drug.1 Infants or young children who accidentally ingest marijuana are more likely to require hospital admission compared to older children who ingest similar concentrations due to their smaller size and weight and increased severity of symptoms.16

Marijuana may be laced with other substances, either known or unknown to the consumer. Using marijuana in combination with other substances may result in greater impairment than when using marijuana alone and may increase the risk of overdose.

Learn more about marijuana and potential risk of poisoning.

If you or someone you know is showing signs that might suggest they have used too much marijuana, call poison control center at: at 1-800-222-1222. In case of emergency, call 9-1-1.

Using alcohol and marijuana at the same time is likely to result in greater impairment than when using either one alone.17 Greater impairment can result in greater risk of physical harm. Using marijuana and tobacco at the same time may also lead to increased exposure to harmful chemicals that could cause greater risks to the lungs and the cardiovascular system (heart and blood vessels).18 Also, marijuana may change how prescription drugs work.19 Always talk with your doctor about any medications you are taking or thinking about taking and the possible side effects when mixed with other things, such as marijuana.

Learn more about marijuana and the risk of using other drugs.

Synthetic cannabinoids (called spice, K2, and other names) are man-made chemicals and, despite the name, are not marijuana or cannabinoid medicines.20 Synthetic cannabinoids are often sprayed onto dried plant material that can then be smoked or sold as liquids to use in vaping devices.

Synthetic cannabinoids are part of a group of unregulated, mind-altering drugs that attempt to produce effects similar to illicit drugs. Their effects are not fully understood and can cause dangerous and unpredictable health effects because of their unpredictable chemical contents.21  Once these products are identified in the illegal marketplace, they are added to the list of schedule I substances by the Drug Enforcement Administrationexternal icon. Schedule I substances are illegal throughout the United States and are defined as having no medical use and high potential for abuse.

Synthetic cannabinoids can affect the brain much more powerfully than marijuana, creating unpredictable and, in some cases, life-threatening effects, including:

  • nausea
  • anxiety
  • paranoia
  • brain swelling
  • seizures
  • hallucinations
  • aggression
  • heart palpitations
  • chest pains

Cases of severe injury and death from use of synthetic cannabinoids have been reported, along with regional outbreaks when a contaminated batch enters a specific community.22 For additional questions around synthetic cannabinoids, visit CDC’s National Center for Environmental Health page on synthetic marijuana or the National Institute on Drug Abuse page on synthetic cannabinoidsexternal icon.

 

If someone you know has used synthetic cannabinoids and needs help, you can take the following steps:

  • Call 911 immediately if someone stops breathing, collapses, or has a seizure. These symptoms can be life-threatening and require immediate medical attention.
  • Call your local poison control center at 1-800-222-1222.
  • Call your doctor.

Breastfeeding persons are encouraged to avoid using marijuana.23 The health effects of a breastfeeding person’s use of marijuana on her infant are not yet fully known, and the available data are limited and conflicting. However, we know that chemicals from marijuana can be passed to a baby through breast milk. In addition, tetrahydrocannabinol (THC) is stored in body fat and is slowly released over time, meaning that a baby could still be exposed even after a breastfeeding person stops using marijuana.

More research about the effects of secondhand marijuana smoke is still needed. The known risks of secondhand exposure to tobacco smoke—including risks to the heart or lungs24—raise questions about whether secondhand exposure to marijuana smoke causes similar health risks. Secondhand marijuana smoke contains many of the same toxic and cancer-causing chemicals found in tobacco smoke and contains some of those chemicals in higher amounts.5

More research is needed to understand how secondhand marijuana exposure may affect children. Secondhand marijuana smoke contains tetrahydrocannabinol (THC), the chemical responsible for most of marijuana’s psychological effects (or the “high”). THC can be passed to infants and children through secondhand smoke, and people exposed to secondhand marijuana smoke can experience psychoactive effects, such as feeling high.25,26 Recent studies have found strong associations between reports of having someone in the home who uses marijuana (e.g., a parent, relative, or caretaker) and the child having detectable levels of THC.27,28

Children exposed to THC are potentially at risk for negative health effects. Other research shows that marijuana use during adolescence can impact the developing teenage brain and cause problems with attention, motivation, and memory, suggesting that secondhand smoke exposure could lead to similar negative health effects in children.29

 

 

The fact that marijuana is legal in some states for medical or nonmedical adult use does not mean that it is safe. Using marijuana at any age can lead to negative health consequences:

  • Using marijuana heavily (daily or near-daily) can damage your memory, attention, and learning ability. This can last a week or more after the last time marijuana was used.1
  • Using marijuana during pregnancy or while breastfeeding may harm the baby.1,29
  • Marijuana use has been linked to social anxiety, depression, suicide, and schizophrenia. Scientists don’t yet know whether marijuana use directly causes these health issues, but it may make symptoms more severe.
  • Smoking any product, including marijuana, can damage your lungs and cardiovascular system (heart and blood vessels).5 Eating or drinking foods with marijuana can take longer to have an effect and may increase the chance of consuming too much.1 Vaping marijuana has led to lung injury and even death.8 Use of concentrates in vaping or dabbing devices may increase a number of health risks because of the concentration or strength of marijuana being used.6,30

  1. National Academies of Sciences, Engineering, and Medicine. The health effects of cannabis and cannabinoids: the current state of evidence and recommendations for research. Washington, DC: The National Academies Press; 2017.
  2. Agriculture Improvement Act of 2018. H.R.2, 115th Cong. 2017-2018. https://www.congress.gov/bill/115th-congress/house-bill/2.external icon
  3. Schauer GL, Njai R, Grant-Lenzy AM. Modes of marijuana use – smoking, vaping, eating, and dabbing: Results from the 2016 BRFSS in 12 States. Drug Alcohol Depend. Apr 1 2020;209:107900.
  4. Schauer GL, King BA, Bunnell RE, Promoff G, McAfee TA. Toking, vaping, and eating for health or fun: marijuana use patterns in adults, US, 2014. American Journal of Preventive Medicine. 2016;50(1):1-8.
  5. Moir D, Rickert WS, Levasseur G, et al. A comparison of mainstream and sidestream marijuana and tobacco cigarette smoke produced under two machine smoking conditions. Chemical Research in Toxicology. 2008;21(2):494-502.
  6. Raber JC, Elzinga S, Kaplan C. Understanding dabs: contamination concerns of cannabis concentrates and cannabinoid transfer during the act of dabbing. The Journal of Toxicological Sciences. 2015;40(6):797-803.
  7. Compton WM, Grant BF, Colliver JD, Glantz MD, Stinson FS. Prevalence of marijuana use disorders in the United States: 1991-1992 and 2001-2002. JAMA. 2004;291(17):2114-2121.
  8. Krishnasamy VP, Hallowell BD, Ko JY, et al. Update: characteristics of a nationwide outbreak of e-cigarette, or vaping, product use–associated lung injury—United States, August 2019–January 2020. Morbidity and Mortality Weekly Report. 2020;69(3):90.
  9. Fattore L, Fratta W. How important are sex differences in cannabinoid action? British Journal of Pharmacology. 2010;160(3):544-548.
  10. Hasin DS, Saha TD, Kerridge BT, et al. Prevalence of marijuana use disorders in the United States between 2001-2002 and 2012-2013. JAMA Psychiatry. 2015;72(12):1235-1242.
  11. Lopez-Quintero C, de los Cobos JP, Hasin DS, et al. Probability and predictors of transition from first use to dependence on nicotine, alcohol, cannabis, and cocaine: Results of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). Drug and Alcohol Dependence. 2011;115(1-2):120-130.
  12. Winters KC, Lee C-YS. Likelihood of developing an alcohol and cannabis use disorder during youth: association with recent use and age. Drug and Alcohol Dependence. 2008;92(1-3):239-247.
  13. ElSohly MA, Mehmedic Z, Foster S, Gon C, Chandra S, Church JC. Changes in cannabis potency over the last 2 decades (1995–2014): analysis of current data in the United States. Biological Psychiatry. 2016;79(7):613-619.
  14. Mauro PM, Carliner H, Brown QL, et al. Age Differences in Daily and Nondaily Cannabis Use in the United States, 2002-2014. Journal of Studies on Alcohol and Drugs. 2018;79(3):423.
  15. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders (5th ed). Washington, DC; 2013.
  16. Wang GS, Le Lait M-C, Deakyne SJ, Bronstein AC, Bajaj L, Roosevelt G. Unintentional pediatric exposures to marijuana in Colorado, 2009-2015. JAMA Pediatrics. 2016;170(9):e160971-e160971.
  17. Yurasek AM, Aston ER, Metrik J. Co-use of alcohol and cannabis: A review. Current Addiction Reports. 2017;4(2):184-193.
  18. Meier E, Hatsukami DK. A review of the additive health risk of cannabis and tobacco co-use. Drug and Alcohol Dependence. 2016;166:6-12.
  19. Antoniou T, Bodkin J, Ho JM. Drug interactions with cannabinoids. CMAJ. 2020;192(9):E206.
  20. Gurney S, Scott K, Kacinko S, Presley B, Logan B. Pharmacology, toxicology, and adverse effects of synthetic cannabinoid drugs. Forensic Sci Rev. 2014;26(1):53-78.
  21. Trecki J, Gerona RR, Schwartz MD. Synthetic cannabinoid-related illnesses and deaths. N Engl J Med. 2015;373(2):103-107.
  22. Roehler DR, Hoots BE, Vivolo-Kantor AM. Regional trends in suspected synthetic cannabinoid exposure from January 2016 to September 2019 in the United States. Drug and Alcohol Dependence. 2020;207:107810.
  23. Ryan SA, Ammerman SD, O’Connor ME. Marijuana use during pregnancy and breastfeeding: implications for neonatal and childhood outcomes. Pediatrics. 2018;142(3).
  24. Alberg AJ, Shopland DR, Cummings KM. The 2014 Surgeon General’s report: commemorating the 50th Anniversary of the 1964 Report of the Advisory Committee to the US Surgeon General and updating the evidence on the health consequences of cigarette smokingexternal icon. American Journal of Epidemiology. 2014;179(4):403-412.
  25. Taylor DR, Poulton R, Moffitt TE, Ramankutty P, Sears MR. The respiratory effects of cannabis dependence in young adults. Addiction. 2000;95(11):1669-1677.
  26. Wilson KM, Torok MR, Wei B, et al. Detecting biomarkers of secondhand marijuana smoke in young children. Pediatric Research. 2017;81(4):589-592.
  27. Moore C, Coulter C, Uges D, et al. Cannabinoids in oral fluid following passive exposure to marijuana smoke. Forensic Science International. 2011;212(1-3):227-230.
  28. Broyd SJ, van Hell HH, Beale C, Yuecel M, Solowij N. Acute and chronic effects of cannabinoids on human cognition—a systematic review. Biological Psychiatry. 2016;79(7):557-567.
  29. Garry A, Rigourd V, Amirouche A, Fauroux V, Aubry S, Serreau R. Cannabis and breastfeeding. Journal of Toxicology. 2009;2009:596149.
  30. Bidwell LC, YorkWilliams SL, Mueller RL, Bryan AD, Hutchison KE. Exploring cannabis concentrates on the legal market: User profiles, product strength, and health-related outcomesexternal icon. Addictive Behaviors Reports. 2018;8:102-106.