Marijuana is a drug that comes from the flowers and leaves of the cannabis plant. These parts of the plant are dried and then either smoked as cigarettes or consumed in other ways.
People consume marijuana in order to alter their state of consciousness or achieve a state of relaxation. This experience is called a high, and it can be achieved through many different means, including smoking, vaporizing, or eating food with marijuana cooked in as an ingredient.
Because marijuana may help treat chronic pain and other conditions, the drug is also consumed for medicinal purposes.
Marijuana also goes by the names pot, weed, grass, and ganja.
Cannabis is the botanical name of the plant, and marijuana is the name for the drug derived from the plant. Cannabis is grown, whereas marijuana is smoked.
While it does not lead to addiction in the way heroin or cocaine does, and many argue that its highs are no more intense or damaging than those given by alcohol, marijuana is illegal under United States federal law.
But certain states, such as California, have made it legal for their residents to consume marijuana either medicinally, or medicinally and recreationally.
How Does Marijuana Make You High? THC vs. CBD
The active ingredients in marijuana are chemicals known as cannabinoids.
Marijuana contains more than 100 cannabinoids — naturally occurring compounds found in plants and animals. They even occur in humans. The cannabinoids present in your brain and throughout your body are called endocannabinoids. These chemicals play an important role in thinking, memory, and sensory perception, according to the National Institute on Drug Abuse (NIDA). (1)
The cannabinoids that produce marijuana’s effects are tetrahydrocannabinol, or THC, and cannabidiol, or CBD. THC and CBD act on different neurological pathways and create different physical and mental reactions.
THC, for instance, is much more psychoactive, which means it can affect the way your brain perceives the world around you. It acts on the body’s endocannabinoid system and is the cannabinoid responsible for making people feel intoxicated or euphoric.
THC is what makes people “high.”
CBD doesn’t act on the same neurological pathways. Researchers believe that CBD acts instead on the brain’s serotonin system, which regulates mood, sleep, appetite, and desire. It may calm and relax you rather than alter your perception. It also doesn’t affect physical reactions as much.
The amount of THC and CBD in each cannabis plant is variable and depends on how it was grown, prepared, and stored. The more THC a plant has, the stronger its effects.
Marijuana also contains hundreds of other chemicals, the amounts varying from plant to plant.
There are two main types of cannabis plants used for marijuana: sativa and indica. Each produces slightly different effects. There are also hybrid plants grown to combine the two strains.
Hemp plants, which are another type of cannabis plant, do not produce anywhere near the high that sativa and indica plants do.
Marijuana’s capacity for relieving stress, relaxing the body, and changing your perception has made it a popular recreational drug for thousands of years.
According to a 2016 report from the United Nations, it’s the most widely used drug in the world. (2)?An estimated 182.5 million people partake of it globally. (2)
Not only is it the world’s most consumed drug, but in the United States, there’s been an estimated six- or sevenfold increase in its potency since the 1970s. (3)?According to a study from 2017, potency has been increasing in similar ways in Europe as well. (4)
From 1995 to 2014, the average amount of THC in marijuana has increased from 4 to 12 percent, says Staci Gruber, PhD, a professor of psychiatry at Harvard Medical School in Boston. She adds that when her lab has analyzed the THC content of the products used by individuals participating in her research over the last few years, they’ve found an average 16 to 18 percent increase. “People want more of a high for their money,” she adds, “and growers have responded accordingly.”
Why Is Marijuana Used as Medicine, and What Conditions Can It Help Treat?
The use of marijuana for medical purposes dates back possibly as far as 5,000 years. (5)
In the United States, over the last few decades, there has been an increase in the acceptability of using marijuana to treat a wide variety of medical conditions.
Because cannabinoids affect physical and mental processes, and it’s thought that they may not produce the adverse effects of prescription drugs, people have found marijuana useful in treating pain, nausea, and loss of appetite related to cancer, AIDS, and other illnesses.
Marijuana has proved?so beneficial in those cases that there are now a handful of Food and Drug Administration (FDA)-approved prescription drugs that contain cannabis or synthetic cannabis. These were designed for and are used to treat AIDS- and cancer-related anorexia. And the FDA has approved a cannabis-based drug to treat seizures in children with rare and severe forms of epilepsy. (6)
According to the National Conference of State Legislators (NCSL), it’s now legal to use some form of marijuana for medicinal purposes in 47 states and the District of Columbia. (7)
Studies suggest that medical use of marijuana may help treat a number of conditions or their symptoms, including anxiety, sleep disorders, chronic pain, spasticity related to multiple sclerosis, arthritis inflammation, and Crohn’s disease. In addition, some people have used marijuana instead of prescription painkillers. (8,9,10)
There are many forms of medical marijuana. It can be smoked, but it can also be consumed as an edible, as a vapor, as a tincture, and in capsules.
Researchers are currently investigating its properties, its potential uses, and what the possible long-term effects of using it medicinally might be.
Since long-term effects aren’t yet known, you should talk to a doctor before incorporating medical marijuana into any treatment plan.
There’s a perception that because this drug comes from a plant, it’s natural and free of harmful toxins or adverse effects. But the increase in potency and lack of regulation of its production means that not all marijuana is safe.
Is Marijuana Helpful in Treating Cancer?
According to the?American Cancer Society, a number of small studies suggest that?marijuana?can help alleviate the nausea and vomiting associated with chemotherapy, as well as nerve and other pain associated with the disease and its treatments. (11)
And a 2017 study showed that up to a quarter of cancer patients reported using marijuana to ease the physical and psychological symptoms of their disease and treatment. Patients say it can ease many of the side effects of chemotherapy, including loss of appetite, nausea, and pain. (12)
What Are the Different Types of Marijuana Plants?
Sativa?These plants are tall and have long, narrow leaves. They’re usually grown outdoors. Because this strain contains more THC, it’s thought that sativa plants have more of a stimulant effect.
Indica?These plants are short, have wider leaves, and are typically grown indoors. Indica plants, which have a higher cannabidiol content, are thought to be?sedatives?and have a more calming effect when taken medicinally. This type of marijuana is sometimes taken at night.
Hybrid?A hybrid is a combination of both sativa and indica plants, and contains characteristics of the two.
Hemp This form of the cannabis plant is grown for fiber that can be used to make rope and textiles. Hemp seeds, like flax or chia seeds, contain protein and other beneficial nutrients.
But this form of cannabis won’t get you high — or as high — as sativa, indica, or hybrid strains, because it contains more CBD than THC (and very low levels of THC at that).
What Are the Different Ways People Consume Marijuana?
Marijuana can be consumed in the following ways.
Inhaling Smoke?With this method, you pack a small amount of dried cannabis into a pipe or rolling paper. You then light it and inhale the smoke from the mouthpiece of the device.
While smoking marijuana is inexpensive and easy, it could be harmful to your lungs because many other toxins are produced by the creation of smoke.
Edibles You can infuse cannabis into butter or oil and cook it into lollipops, ice cream, gummy bears, mints, and chocolate bars.
Eating cannabis is a popular alternative to smoking it, though the potency of edibles varies immensely and can cause strong side effects that can last for hours.
Because it takes longer to absorb THC through digestion, it can take longer for the effects to take hold, and longer for them to wear off. (13)
Vaporizers To vaporize marijuana, a small amount of dried cannabis or cannabis extract is placed into a vaporizer machine to be inhaled.
This option allows you to inhale vapor instead of smoke. It’s thought that this method may be less harmful for the lungs than smoking, but more research needs to be done. (14)
CBD?Oil This?is made by extracting a resin from marijuana or hemp plants. Extractions from marijuana plants are much more potent and effective than extracts from hemp plants.
Tinctures or Sprays A tincture is a concentrated form of medical marijuana that’s often mixed with alcohol, glycerin, or a substance called medium chain triglyceride (MCT) oil. (MCT is found in coconut oil.)
You can squirt or spray the solution under your tongue. It can also be mixed with water or other beverages. A downside to using this method is that it can be expensive: Tinctures can cost up to $60 for a small bottle.
Patches A small patch can deliver marijuana through the skin. It’s most often worn on the wrist, foot, or ankle.
Single patches usually last up to eight hours.
Topical Products Salves, ointments, lotions, and oils can be used for aches and pains. These topical options don’t cause a “high.”
Dabbing In dabbing, a small amount of thick wax or oil containing plant-extracted THC is heated through a glass pipe and a metal rod with a butane torch.
This may not be a safe way to consume the drug because experts think that the chemicals involved in the preparation of the oils and the heat from the torch may create harmful toxins. (15)
Why Is Marijuana (Mostly) Illegal, and Where Is It Legal?
Marijuana use hasn’t always been illegal in the United States.
In the late 19th?and early 20th?centuries, doctors around the world prescribed the herb as a treatment for headaches, pain, asthma, and even gonorrhea. (16)?But over time, as the 20th?century progressed, advances in pharmaceutical technology meant consumers could use more than plants to treat illness, (16)?and Congress passed increasingly stringent laws that eventually criminalized the drug.
In 1970, with the passage of the Controlled Substances Act, the government classified marijuana as a Schedule I drug. (16)?This means, according to the U.S. government’s Drug Enforcement Agency (DEA), that the drug has no medical use and is instead a substance that has high potential for abuse. Heroin, LSD, and ecstasy are also Schedule I drugs. (17)
In comparison, Schedule II drugs, such as cocaine, oxycodone (OxyContin), and methylphenidate (Ritalin), are substances that the DEA believes to have a high potential for both abuse and severe physical and psychological addiction. (17)
Near the end of the ’70s, the government began to shift its hard-line stance a bit. In 1978, the FDA created the Investigational New Drug Compassionate Access Program. (18)?It allowed individuals with serious medical conditions that could only be alleviated by marijuana to receive the drug from the government. (The program still exists, but as of 1992 it stopped taking new applicants.) (18)
In 1996, California became the first state to allow the use of medical marijuana. (19)
The National Council of State Legislatures (NCSL) and the National Organization for the Reform of Marijuana Laws (NORML, an organization that tracks marijuana law developments) maintain up-to-date lists of which states have made what forms of the drug legal. (20,21) Some states may not legalize marijuana for medicinal use, but have legalized forms of high-CBD/low-THC products instead. (7)
What Happens if I Take Too Much?
Not everyone reacts to pot in the same way. Some people may feel euphoric, some may not feel much of anything at all, and others may have an experience they’d prefer not to repeat.
Before you use medical marijuana, it’s important to talk with your doctor about any medical conditions you have. You should also talk to your doctor about your history of alcohol and drug use.
Marijuana, particularly in large doses, and particularly with high THC content, can lead to nausea, panic attacks, and even psychosis. According to the Cleveland Clinic, it can also cause hallucinations and paranoia. (22)
The kind of reaction you have also depends on the way you consume marijuana.
“The body processes edibles in a different way from the way it processes smoked marijuana,” says Dr. Gruber.
“The effects of edibles can take longer to appear, and last longer when they do, because they have to pass through the liver as you digest them — and in this process the THC is converted to a more potent substance.” With smoked marijuana, she adds, since the THC doesn’t have to be digested, the effects come on much quicker.
On average, it takes 30 to 60 minutes after ingestion of an edible for the effects to be felt, and they can last for up to 10 hours; it only takes seconds or minutes to feel the high when smoking. (24)
Your response to the drug, says Gruber, depends on several factors. They include:
- How hydrated were you?
- What did you eat?
- Were you anxious or experiencing other intense emotions before you took the drug?
- Were you also drinking alcohol?
- How large was the dose?
- How long have you been using?
- Was it your first time?
- How did you consume it?
Not only can you take too much, but you can take the wrong kind. There is a kind of synthetic marijuana, different from pharmaceutical-grade marijuana, which is chemically very close to plant cannabis but engineered to be much more potent and psychoactive. Synthetic marijuana can be marketed as herbal, but is actually entirely chemical and can lead to fatalities. (4)
What Can Pot Do to My Brain and Body?
The drug may cause the following short-term effects: (25)
- Poor short-term memory
- Impaired ability to drive or operate machinery
- Increased heart rate
- Impaired judgment and decision-making
- Panic or acute psychosis (in high doses)
According to researchers at NIDA, long-term or heavy use may cause the following adverse effects: (25)
- Chronic bronchitis and other respiratory problems
- Lower IQ and other cognitive impairments
- Increased risk of schizophrenia and psychosis in those predisposed to the conditions
According to the National Alliance on Mental Illness, your risk of developing schizophrenia and psychosis increases as your use increases. Your risk also increases the younger you are at the age when you begin using. (26)
THC and CBD can also affect the way the liver metabolizes certain other drugs.
THC can decrease the amount of a drug circulating in your blood, which would make the drug less effective. It’s thought to have this effect on: (27)
- clozapine (Clozaril)
- duloxetine (Cymbalta)
- naproxen (Aleve)
- cyclobenzaprine (Flexeril)
- olanzapine (Zyprexa)
CBD does the opposite. It acts on two other liver enzymes in a way that can increase the amount of a drug in your system. One of these enzymes helps metabolize about 25 percent of all prescription medications, including some statins. The other enzyme metabolizes many antidepressants and opioids like codeine. (27)
Drugs that could be affected by CBD include: (27)
Is Marijuana Addictive?
Using marijuana can, in certain circumstances, lead to dependency on the drug — but it does not appear to create a dependency at the rate of alcohol or heroin. According to NIDA, an estimated 9 percent of marijuana users will become addicted to it. (28)?That number goes up to about 17 percent among those who start using marijuana as teenagers. (28)
In contrast, an estimated 32 percent may become dependent on tobacco, and an estimated 17 percent on heroin. (29)
But experts think that it may not just be the chemical makeup of marijuana itself that’s causing the addiction — it may be that there are other societal and psychological factors at play when a person becomes dependent on the drug.
How Else Will Marijuana Affect My Brain?
Depending on your age, the dose, and how regularly you use it, marijuana does affect the brain, both in the moment and over time.
The population that may experience the most pronounced effects are young people.
“Across the board, it’s predominantly agreed that THC exposure when your brain is still under construction might not be beneficial,” says Gruber.
Those who start using marijuana at a young age may be at greater risk for long-term effects on thinking and memory. This is because it affects the region of the brain responsible for executive functioning, which develops last. Executive functioning refers to the processes that have to do with decision making, problem-solving, planning, and memory.
One study showed that teenagers who started smoking between ages 14 and 22 — but who stopped at 22 — had significantly more cognitive difficulties than those who did not smoke.?(30) Another study found that adults who had started smoking marijuana before they were 17 showed significant impairments in verbal fluency, memory, and abstract reasoning. (31)
How Will Smoking Weed Affect My Lungs?
Research has shown that long-term smoking can have negative effects on the respiratory system. (8)
Because marijuana contains some of the same toxins and carcinogens as tobacco, regular users may experience:
- Chronic bronchitis
- Increased phlegm production
- Decreased lung function
Will I Get Lung Cancer From Smoking Pot?
While smoked marijuana has a similar toxin profile to tobacco, studies suggest only a weak association between cannabis smoking and lung cancer. So it’s very unlikely that you’ll develop lung cancer as a result of smoking only marijuana. (33)
A large 2015 analysis of thousands of lung cancer cases found that between non-habitual marijuana smokers and habitual smokers, there was no statistically significant difference in the risk of developing lung cancer. (34)
How Will Marijuana Affect My Heart?
Marijuana can increase your heart rate, and there is a small chance that it could lead to more serious cardiovascular problems.
This increase in heart rate could possibly make cannabis users more susceptible to heart attacks than nonusers, but the research on this isn’t sufficient, according to a 2017 report. (37)
How Long Does Marijuana Stay in Your System?
Even though marijuana’s effects usually only last for a few hours, THC can stay in the body for days or even weeks. (39)
But the more you use the drug, the longer it can stick around.
A single use can be detected by urine tests up to three days later. If you’re a heavy, chronic user, the drug can be detected up to 30 days after a single use. (40)
Can I Smoke Marijuana While I’m Pregnant?
An increasing number of women — particularly those younger than 24 — are using marijuana while pregnant. (41) Women are finding that it can help treat the nausea, anxiety, and stress that can accompany pregnancy.
But marijuana can be passed to infants through the placenta, just like other drugs that women are cautioned to avoid while pregnant.
So what exactly are the risks?
“That’s a big question,” says Judy Chang, MD, MPH, a professor in the department of obstetrics, gynecology, and reproductive sciences at the University of Pittsburgh. Dr. Chang is currently researching the attitudes and beliefs of women who use marijuana while pregnant.
She says that the major studies that have looked at use in pregnancy seem to suggest that children of mothers who consume marijuana while pregnant may experience negative cognitive effects.
These studies found that children whose mothers used marijuana during pregnancy were at greater risk for difficulties with attention, memory, and impulse control later in childhood. (42)?These children, other research has found, may also be more likely to grow up and use marijuana themselves. (43)
“The key takeaway is that there may be some impact to the brain,” Chang says. “And no studies at all indicate a benefit.”
In addition, these large studies might be outmoded. Chang points out that they were conducted at a time when the drug wasn’t as potent, and the main method of consumption was smoking. THC content has increased exponentially over the years, she adds, and people are consuming edibles more, which have a stronger effect.
“Regular use used to mean smoking a joint three times a week,” says Chang. “The women we talk to are smoking more frequently than that, and they’re not necessarily using it in cigarette form.”
Because it’s not quite clear how use can affect the children of mothers who consume the drug while pregnant or breastfeeding, the American College of Obstetricians and Gynecologists discourages using marijuana during these times. (44)
Mothers who are considering using marijuana while pregnant may also face another unwanted complication: Consuming the drug while pregnant is considered child abuse in at least 24 states. (45)
Like alcohol and other drugs, using marijuana can impair your ability to drive, operate machinery, or perform any activity that requires you to be alert.
According to reporting done in 2017 by The Denver Post, the number of fatal car crashes linked to marijuana use has risen sharply in Colorado since the state legalized it in 2012. The number has risen each year — and so has the potency of the marijuana found in the systems of those who died in these accidents. (46)
There have also been reports of children being adversely affected after accidentally eating edibles intended for adults. If you are going to keep edibles around, make sure they are in a place where no children can find them.
Editorial Sources and Fact-Checking
- How Does Marijuana Produce Its Effects? National Institute on Drug Abuse. July 2020.
- World Drug Report 2016. United Nations Office on Drugs and Crime. May 2016.
- Sevigny EL. Is Today’s Marijuana More Potent Simply Because It’s Fresher? Drug Testing and Analysis. January 2013.
- Lafaye G, Karila L, Blecha L,?Benyamina A. Cannabis, Cannabinoids, and Health. Dialogues in Clinical Neuroscience. September 2017.
- Bridgeman MB,?Abazia DT. Medicinal Cannabis: History, Pharmacology, and Implications for the Acute Care Setting. Pharmacy and Therapeutics. March 2017.
- FDA Approves First Drug Comprised of an Active Ingredient Derived From Marijuana to Treat Rare, Severe Forms of Epilepsy. U.S. Food and Drug Administration. June 25, 2018.
- State Medical Cannabis Laws. National Conference of State Legislatures. November 9, 2022.
- The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research. National Academies of Sciences, Engineering, and Medicine. 2017.
- Philpott HT, O’Brien M, McDougall JJ. Attenuation of Early Phase Inflammation by Cannabidiol Prevents Pain and Nerve Damage in Rat Osteoarthritis.?Pain. December 2017.
- Storr M, Devlin S, Kaplan GG, et al. Cannabis Use Provides Symptom Relief in Patients With Inflammatory Bowel Disease But Is Associated With Worse Disease Prognosis in Patients With Crohn’s Disease.?Inflammatory Bowel Diseases. March 1, 2014.
- Marijuana and Cancer. American Cancer Society. August 3, 2022.
- Pergam SA, Woodfield MC, Lee CM, et al. Cannabis Use Among Patients at a Comprehensive Cancer Center in a State With Legalized Medicinal and Recreational Use. Cancer. November 15, 2017.
- Hancock-Allen JB, Barker L, VanDyke M, Holmes DB. Notes From the Field:?Death Following Ingestion of an Edible Marijuana Product — Colorado, March 2014. Centers for Disease Control and Prevention Morbidity and Mortality Weekly Report.?July 24, 2015.
- Loflin M, Earleywine M. No Smoke, No Fire: What the Initial Literature Suggests Regarding Vapourized Cannabis and Respiratory Risk. Canadian Journal of Respiratory Therapy. 2015.
- Meehan-Atrash J, Luo W, Strongin RM. Toxicant Formation in Dabbing: The Terpene Story [PDF]. ACS Omega. September 2017.
- Mack A, Joy J. Can Marijuana Help? Marijuana as Medicine??The Science Beyond the Controversy. 2001.
- Drug Scheduling. U.S. Drug Enforcement Administration.
- Eddy M. Medical Marijuana: Review and Analysis of Federal and State Policies [PDF]. Congressional Research Service. April 2, 2010.
- California Marijuana Laws. FindLaw.?November 19, 2019.
- Deep Dive: Marijuana. National Conference of State Legislatures.
- State Laws. NORML.
- Marijuana. Cleveland Clinic. December 28, 2020.
- Deleted, December 6, 2022.
- Marijuana. Colorado Department of Public Health and Environment.
- Volkow ND, Baler RD, Compton WM, Weiss SRB. Adverse Health Effects of Marijuana Use. The New England Journal of Medicine. June 5, 2014.
- McCance-Katz EF. Substance Use Carries Mental Health Risks — Yes, Even Marijuana. National Alliance on Mental Illness. March 26, 2018.
- Fugh-Berman A, Wood S, Kogan M, et al. Medical Cannabis: Adverse Effects and Drug Interactions [PDF]. Government of the District of Columbia Department of Health.
- Is Marijuana Addictive? National Institute on Drug Abuse. July 2020.
- Bostwick JM. Blurred Boundaries: The Therapeutics and Politics of Medical Marijuana. Mayo Clinic Proceedings. February 2012.
- Brook JS, Stimmel MA, Zhang C, Brook DW. The Association Between Early Marijuana Use and Subsequent Academic Achievement and Health Problems: A Longitudinal Study. American Journal on Addictions. March–April 2008.
- Pope HG, Gruber AJ, Hudson JI, et al. Early-Onset Cannabis Use and Cognitive Deficits: What Is the Nature of the Association? Drug and Alcohol Dependence. April 1, 2003.
- Ribeiro LIG,?Ind PW. Effect of Cannabis Smoking on Lung Function and Respiratory Symptoms: A Structured Literature Review. NPJ Primary Care Respiratory Medicine. October 20, 2016.
- Tashkin DP.?Marijuana and Lung Disease.?CHEST. September 1, 2018.
- Zhang LR, Morgenstern H, Greenland S, et al. Cannabis Smoking and Lung Cancer Risk: Pooled Analysis in the International Lung Cancer Consortium. International Journal of Cancer. February 15, 2015.
- Mack A, Joy J. How Harmful Is Marijuana? Marijuana as Medicine??The Science Beyond the Controversy. 2001.
- Cannabis (Marijuana) DrugFacts. National Institute on Drug Abuse. December 2019.
- Cardiometabolic Risk. The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research. 2017.
- Deleted, November 4, 2022.
- What Are Marijuana’s Effects? National Institute on Drug Abuse. July 2020.
- Marijuana Δ9-Tetrahydrocannabinol (THC). Mayo Clinic Laboratories.
- Young-Wolff KC, Tucker L-Y, Alexeeff S, et al. Trends in Self-Reported and Biochemically Tested Marijuana Use Among Pregnant Females in California From 2009–2016. JAMA. December 26, 2017.
- Warner TD, Roussos-Ross D,?Behnke M. It’s Not Your Mother’s Marijuana: Effects on Maternal-Fetal Health and the Developing Child. Clinics in Perinatology. December 2014.
- Badowski S. Cannabis Use During Pregnancy and Postpartum. Canadian Family Physician. February 2020.
- Marijuana Use During Pregnancy and Lactation.?American College of Obstetricians and Gynecologists. October 2017.
- Varney S. Is Smoking Pot While Pregnant Safe for the Baby? NPR Morning Edition. January 29, 2018.
- Migoya D. Exclusive: Traffic Fatalities Linked to Marijuana Are Up Sharply in Colorado. Is Legalization to Blame? The Denver Post. December 28, 2018.