What to Know About Marijuana Use
Steven Gans, MD is board-certified in psychiatry and is an active supervisor, teacher, and mentor at Massachusetts General Hospital.
LPETTET / Getty Images
Marijuana refers to the dried leaves, stems, flowers, and seeds from the hemp plant Cannabis. The main active ingredient in marijuana is the mind-altering chemical delta-9-tetrahydrocannabinol (THC).
Marijuana is the most common illegal drug used in the United States. According to a national survey on drug use and health from 2018, about 43.5 million Americans over the age of 12 used marijuana in the last year.
As of the 2018 midterm elections, 10 states and Washington, DC had legalized marijuana for recreational use for adults over the age of 21. Over 30 states have laws on the books legalizing marijuana for medical use only, while several others have only legalized oils with low-THC content. Marijuana is still illegal under federal law.
Also Known As: There are over 200 slang terms for marijuana, including pot, herb, weed, grass, widow, boom, ganja, hash, Mary Jane, cannabis, bubble gum, northern lights, fruity juice, gangster, Afghani #1, skunk, and chronic.
Drug Class: Marijuana is often classified as a depressant, although it also has stimulant and hallucinogenic properties.
Common Side Effects: Side effects of marijuana use include altered senses, mood changes, difficulty thinking, and impaired memory. In high doses, it can lead to hallucinations, psychosis, and delusions.
How to Recognize Marijuana
Marijuana looks like a shredded, green-brown mix of plant material. But it can look different depending on how it is prepared or packaged.
What Does Marijuana Do?
The membranes of certain nerve cells in the brain contain receptors that bind to THC, kicking off a series of cellular reactions that ultimately lead to the high people experience when they use marijuana. People use the drug because it elevates their mood and relaxes them. Depending on the level of THC, users may also experience euphoria, hallucinations, and paranoia.
The most common way to use marijuana is to smoke it. It is often rolled into a cigarette “joint,” added to an emptied cigar casing to create a “blunt,” or smoked in a pipe or a water pipe “bong.”
A newly popular method of use is smoking or eating different forms of THC-rich resins extracted from the marijuana plant. It can also be baked into food (called edibles) such as brownies, cookies, or candy, or brewed as a tea.
What the Experts Say
Marijuana use can be particularly problematic among teens because it may have a long-term impact on mental abilities including memory, learning, and thinking. One 2012 study found that participants who had begun smoking marijuana in their teens lost an average of eight IQ points.
Because the most common method of use is smoking, marijuana use also poses respiratory risks and other smoking-related dangers. Smoking marijuana may increase the risk of wheezing, shortness of breath, and chronic coughing. According to a review published in 2015, research is mixed on whether or not smoking marijuana increases the risk of cancer. Some studies have suggested that there may be an increased risk, while others have found that marijuana use may actually have a protective effect.
Despite these risks, there are reasons why people choose to continue to use marijuana. One study published in 2016 found people report using marijuana to:
- Relieve stress or tension
- Escape life’s problems
- Ease boredom
- Feel good or euphoric
- Fit in socially
Off-Label or Recently Approved Uses
In addition to its use as a recreational drug, marijuana has a long history of use for medicinal purposes. While it has not been approved by the FDA, many states in the U.S. have legalized marijuana for at least some medical purposes.
Medical marijuana is utilized to treat the symptoms of conditions rather than as a treatment for the condition itself. Research through 2017 suggests that marijuana is most effective in the treatment of muscles spasms, chronic pain, and nausea, making it helpful in relieving the symptoms of conditions such as multiple sclerosis (MS) and epilepsy.
Some of the conditions that medical marijuana has been approved to treat in many states include:
- Alzheimer’s disease
- Crohn’s disease
- Eating disorders
- Severe pain
- Severe nausea
- Persistent muscle spasms
- Wasting syndrome
Further research on the potential benefits of medical marijuana is ongoing. Recognized and legally sanctioned use of marijuana for the treatment or relief of symptoms will continue to evolve as researchers investigate these uses.
As of 2019, medical marijuana is legal in 33 states as well as Washington, D.C.
Common Side Effects
Some of the common side effects of using marijuana include dry mouth, swollen eyelids, bloodshot eyes, loss of coordination, and an accelerated heart rate.
Short-term risks include:
- Anxiety and paranoia
- Impaired memory
- Difficulty thinking
- Learning difficulties
- Lack of attention and focus
- Poor driving skills
Long-term risks potentially include:
- Respiratory problems
- Heightened risk of infections, especially the lungs
- Poor short-term recall
- Cognitive impairment
- Lack of motivation
Regular marijuana smokers may also have many of the same respiratory problems that tobacco smokers have, including daily cough and phlegm, symptoms of chronic bronchitis, and more frequent chest colds. Continuing to smoke marijuana can lead to abnormal functioning of lung tissue injured or destroyed by marijuana smoke.
While some of these risks can’t be mitigated, there are things you can do to address—at least in part—some of the above, if you choose to smoke.
Signs of Use
Marijuana can be consumed in a number of ways, although smoking is the most common method. If you suspect that someone you know is misusing marijuana recreationally, you may notice some of the following signs:
- Lack of focus
- Increased food cravings
- Bloodshot eyes
- Poor time management
- Drug paraphernalia (e.g., pipes, baggies, rolling papers)
It is important to remember that many of these signs may be caused by other things or may simply be variations in normal behavior. Watch for groups of behaviors rather than taking single actions as proof of drug use.
Myths and Common Questions
One common myth is that marijuana is a gateway drug that almost always leads to the use of “harder” drugs. While there is some evidence that exposure to marijuana may make it easier to use other substances, the National Institute on Drug Abuse (NIDA) suggests that most people who use marijuana do not go on to become addicted to other drugs.
Another common myth is that marijuana itself is not addictive. While it is not common, repeated use can lead to both mental and physical dependence. The Centers for Disease Control reports that as many as 1 in 10 people who use marijuana will develop an addiction. Marijuana today often contains much higher THC levels than in the past, which increases its addictive properties.
Tolerance, Dependence, and Withdrawal
Research suggests that regular use of marijuana may lead to tolerance. When tolerance occurs, it takes increasingly larger doses or more frequent use to achieve the same effects. In a 2018 study, researchers found that regular use of marijuana led to less prominent effects when compared to non-regular use. The research also found that the physiological, behavioral, and cognitive effects of marijuana decrease over repeated exposure.
How Long Does Marijuana Stay In Your System?
The amount of time marijuana stays in your system may depend on the dose and frequency of use. Typically, marijuana may be detected in urine tests for up to 13 days after use, however, regular use may lead to longer detection windows. The type of test used can also influence detection windows. While marijuana is only detectable by blood for a few hours, it can be detected by hair follicle tests for up to 90 days.
Research published in 2015 showed that over 30% of marijuana users in the United States had use disorder in 2012 and 2013. Long-term marijuana users are more susceptible to addiction. People who begin using marijuana before age 18 are four to seven times more likely than adults ages 22–26 to develop an addiction.
Drug craving and withdrawal symptoms can make it hard for long-term marijuana smokers to stop using the drug. People trying to quit report irritability, sleeplessness, and anxiety.
A drug is considered addictive if it causes someone to compulsively, and often uncontrollably, crave, seek, and use it, even in the face of negative health and social consequences. Marijuana meets this criterion.
Some of the common symptoms of marijuana withdrawal that people report experiencing include:
- Difficulty sleeping
- Drug cravings
- Decreased appetite
- Mood changes
- Chills and sweats
These symptoms can range from mild to more severe. These withdrawal symptoms can usually be self-managed, although you should talk to your doctor if they become severe, prolonged, or if you experience symptoms of depression.
How to Get Help
Treatment for marijuana use often utilizes counseling and psychotherapy. The goal is to help people learn new behaviors and address any additional addictions or co-occurring psychiatric conditions.
Forms of counseling or therapy that may be effective include:
- Cognitive-behavioral therapy
- Motivational incentives
- Individual or group counseling
- Family therapy
- Support groups
While there is no medication approved for the treatment of marijuana disorder, antidepressants and other medications may be used to treat symptoms of conditions such as depression or anxiety.
If marijuana use becomes a problem for you, talk to your doctor or call the Substance Abuse and Mental Health Services Administration’s national helpline at 1-800-662-HELP (4357).
Marijuana is the most commonly used illegal drug. It can be used for recreation and medical reasons.