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Are medical marijuana users at risk of becoming addicted?

“I can’t sleep, I get irritable, I have anxiety. I get these zaps in my fingers, and my head can’t stop craving cannabis. I can’t function.”

These are the complaints of a medical marijuana user to addiction psychiatrist Dr. Timothy Fong. His patient “couldn’t get seven days off without going back to using again.” And yet, despite many cries for help like these, advocates and detractors of marijuana still debate whether it is addictive or not.

Dr. Mehmet Oz, medical TV show host, says it is important to distinguish between medical and recreational marijuana. The first is used to treat legitimate medical ailments like severe pain, seizures, glaucoma, and nausea from chemotherapy. The second is taken to get high.

Dr. Fong, the director of UCLA’s Addiction Psychiatry Fellowship, adds, “A drug is something you take in your body that changes your body’s organs and how it functions. But a medication is a drug that restores normal functioning. Addiction is a genetic disease. For a substance to be addictive, it has to be: accessible, available, affordable, and anonymous.”

To determine which side is right, it may be helpful to illustrate how cannabis affects the brain.

Marijuana and the brain

The cannabis plant, where marijuana comes from, consists of around 400 chemical compounds. Of these, two main ingredients are used as bases by opposing factions to determine whether it is good or bad for the body and mind. These are delta-9- tetrahydrocannabinol (THC, the principal psychoactive ingredient responsible for many negative effects) and cannabidiol (CBD, which promotes therapeutic effects).

THC may relieve pain by interrupting signals between areas of the brain that process emotions and sensory signals, while CBD attaches to cannabinoid receptors in the brain dealing with anxiety and pain. In contrast, pain relievers like morphine, codeine, oxycodone, and hydrocodone (brand example: Vicodin) block pain messages sent to the brain by binding to opioid receptors.

Cannabis affects everyone differently. Not everyone can tolerate its potency. Some experience withdrawal symptoms after stopping it, others don’t. Some are genetically predisposed to cannabis withdrawal syndrome. That’s why people need to weigh the benefits against the risks.

The stance of major authorities and publications on addiction

Both the National Institute on Drug Abuse (NIDA) and the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5) identify marijuana as an addictive drug. Depending on severity, marijuana users can develop marijuana use disorder (or marijuana addiction).

DSM-5 associates frequent use of marijuana with the development of physiological drug dependence (a definite withdrawal syndrome), and addiction. It has merged cannabis abuse and marijuana dependence to a singular category called ‘cannabis use disorder’.

New to DSM-5 is the acknowledgement that abruptly stopping daily or near-daily use of marijuana often results in the onset of cannabis withdrawal syndrome. This is the first time the DSM has recognized cannabis withdrawal as a diagnosable medical condition.

This information, plus the presence of THC in marijuana, has prompted medical experts to state that health risks exist regardless of how marijuana is used. The Centers for Disease Control and Prevention (CDC) confirm this. Scientists, addiction specialists, researchers—and especially emergency room personnel who regularly encounter cannabis addiction-related visits—agree. Of course, one has to consider statistics too.

Data on cannabis users in the United States

Dr. Fong, citing a 2006 national survey by Stinson et al, says that the lifetime risk of developing addiction to cannabis is about 9%, compared to the lifetime risk of dependence on the following:

  • nicotine: 32%
  • heroin: 23%
  • cocaine: 17%
  • alcohol: 15%

He warns, though: “Nine percent is low, but not zero. This means that from the very first time a person touches cannabis, there is a significant chance they can develop cannabis use disorder.”

This significance is reflected in following 12-month prevalence rates – how widespread the use of cannabis is in different age groups:

  • 3.4% among 12- to 17-year-olds
  • 1.5% among adults aged 18 years and older
  • Use decreases from 18- to 29-year-olds (4.4%) to age 65 years and older (0.01%).
  • In Los Angeles County, marijuana use accounts for more substance use disorder treatment admissions (23.3%) than any other drug, including alcohol (22%).

Data on medical cannabis and pain relief

According to the Substance Abuse and Mental Health Services Administration (SAMHSA), marijuana is the most commonly abused illicit drug in the US.

80% of medical cannabis users substitute marijuana for opioid or benzodiazepine prescription medications for the treatment of acute and chronic pain. Of these, 88% report minor and major pain relief.

Over 200,000 people sought treatment for marijuana addiction in 2015, compared with about 4 million in 2017.

According to the CDC, about 20.4% of adults in the US with chronic pain, and 8% with severe chronic pain, claim that cannabis has fewer side effects and is easier to manage than other pain relief medications. In addition to pain relief, many also use cannabis for sleep and mood regulation.

Cannabis, though moderately beneficial for chronic pain, may not work for acute or post-surgical pain. For some, it might even worsen.

Risks may differ with the way marijuana is used

Some negative effects of marijuana include difficulty with memory, thought processes, problem resolution, learning, attentiveness, and coordination. Frequent use can lead to addiction.


Smoke from marijuana has the same irritants, toxins, and carcinogens as tobacco/cigars, and can lead to an increased risk of respiratory diseases. Marijuana is the only medication that is smoked. As it is not completely understood, there are legitimate concerns about the long-term effects of marijuana smoke on the lungs [1].


As these take longer to digest, they’re also slow to take effect, so people tend to consume more in hopes of accomplishing faster results. This may lead to negative effects such as agitation, paranoia, anxiety, and mental health conditions like psychotic reactions (hallucinations, delusions).

Distribution of marijuana

Dr. Daniel Clauw, Director of the University of Michigan’s Chronic Pain and Fatigue Research Center, is concerned about dispensaries selling “mainly very high THC strains of cannabis or edibles”. He cites the danger of people self-treating pain with cannabis from dispensaries that cater to recreational users. He says, “Those are not the strains people should be using for most of the medicinal effects of marijuana, especially analgesic or pain-relieving effects.”

As marijuana for medicine has the term ‘medical’ attached to it, there is an erroneous assumption that it is the same as any other doctor-prescribed medication. There is currently no universally agreed-upon system that regulates the manufacture, cultivation, approval, prescription, and distribution of medical marijuana. That’s why the US Food and Drug Administration (FDA) and the Drug Enforcement Administration (DEA) are still restricting it.

Is marijuana viable as a substitute for opioid addiction treatments?

As of 2019, per the National Council on State Legislatures, 33 states, Washington (District of Columbia), Guam, and Puerto Rico have legalized cannabis for medical purposes. Washington DC and 10 states have legalized it for recreational use. New York and Illinois recently approved cannabis as a substitute for opioid addiction treatments.

Many medical professionals do not agree with the legalization of marijuana, because even though many assume that cannabis is safer than opioids, this hasn’t been extensively proven in clinical trials. There are concerns that substitution is potentially harmful.

Those who disagree include addiction experts Keith Humphreys, professor of psychiatry and behavioural sciences at Stanford University, and Dr. Richard Saitz, professor and chair of the Department of Community Health Sciences at the Boston University School of Public Health.

Dr. Oz, on the other hand, is an outspoken advocate of medical marijuana. He is petitioning the US federal government to acknowledge medical marijuana as a solution for chronic pain, citing this claim in the 2017 publication of the National Academy of Sciences.

DEA restrictions impede marijuana research

Dr. Oz laments that despite many states having already legalized marijuana, the DEA still considers it a Schedule 1 drug (along with ecstasy, LSD, and heroin), which means it is still considered illegal under federal law. Moreover, Schedule 1 drugs are seen to have no medical use, and to have a high-risk abuse potential. The DEA does not believe that this drug schedule classification should be changed on a federal level.

This restriction and limited government funding make it difficult for researchers to study marijuana’s potential medical value. Until recently, it was illegal for researchers to grow it for studies.

Dr. Oz points out that where marijuana is legal, the opioid overdose death rate is 25% lower. He adds, “The hypocrisy here is that studies don’t show that opioids work for chronic pain. Opioid abuse costs us $78 billion a year. In 2017, we’re spending less than one-tenth of 1% of this total to support cannabis research.”

Minor triumph for marijuana replacement advocates

In April, a study presented at the American Society for Pharmacology and Experimental Therapeutics annual meeting—held during the 2019 Experimental Biology meeting in Florida— revealed that the combination of cannabinoids and morphine did not intensify impulsive behaviour or impair cognition in its monkey test subjects. Researchers interpret this to mean that opioid-cannabinoid mixtures can be used to treat pain, decrease opioid dosage, and reduce the risk of opioid addiction. This experiment has yet to be tested on humans.

Past studies have shown that cannabinoids in marijuana heighten the pain-relieving benefits of opioid drugs but do not amplify their addictive effects or the risks of overdose. Individually, cannabis and opioids have been known to impair memory, among other adverse consequences, making doctors wary of combining them for fear of intensifying these effects. But this particular study refutes this belief.

Marijuana and pancreatic cancer

Pancreatic cancer is the latest to be included in the list of chronic diseases whose symptoms marijuana is purported to alleviate [2]. Scientists from Harvard University’s Dana-Farber Cancer Institute presented evidence that FBL-03G, a chemical derivative of a cannabis flavonoid (natural compound in vegetation and fruits), is capable of killing tumor cells locally and metastatically (when they’ve spread out from the original site).

FBL-03G has anti-inflammatory effects, giving it massive therapy potential. The study, published in Frontiers of Oncology on July 23, is the first to demonstrate the potential new treatment for pancreatic cancer.

London researcher Marilyn Barrett discovered flavonoids from cannabis in 1986. Since flavonoids can only be found in 0.14% of a marijuana plant, scientists genetically engineered them to study their benefits. This development is significant because pancreatic cancer, predicted to be the second leading cause of cancer-related death by 2020, is resistant to current treatments.

The five premises

Dr. Fong cites five concepts as the main concerns of addiction psychiatrists. As a professor of psychiatry at the SEMEL Institute for Neuroscience and Human Behaviour, UCLA, he addressed these in a 2017 seminar:

1: Cannabis is harmless

“Cannabis can be harmful for some, but not all. The vast majority of cannabis users don’t develop this drug use disorder, but for those that do, it’s really difficult.”

2: No one dies from cannabis overdose

New Jersey mom Kristina Ziobro vehemently disagrees with this. She is absolutely certain that marijuana caused her son Michael’s death. She wants the public to know the risks of using it.

Union County medical examiner Dr. Junaid Shaikh discovered the presence of cannabis in Michael’s bloodstream. Kristina and her husband found medical marijuana in his room. Yet Dr. Shaikh wasn’t able to attribute the cause of death to smoking cannabis, citing: “For a drug to be listed as the primary cause of death, it must actually cause the death through overdose rather than simply being a potential contributing factor.”

Dr. Fong’s position: “Partly true, but (users) do die from cannabis intoxication. They die when they’re under the influence of cannabis: car accidents, jumping from bridges, developing a psychotic state, and falling off high (structures).”

3: Cannabis is not addictive

“It absolutely is,” Dr. Fong counters. Addiction aside, what about the psychological consequences?

“If I said to a high school senior, if you start using cannabis, there is a 1 out of 10 chance that you will develop a psychiatric disorder that is harmful and causes suffering that can really ruin your life and career, are those odds you want to get into?”

Those who need convincing should consider the following:

  • According to an article in Neuroscience by Maldonado et al, “10% of those who use cannabis become addicted. The rate is higher among adolescents. Users who seek treatment for marijuana addiction average 10 years of daily use [3, 4].”
  • NIDA warns that marijuana can be addictive and could be considered a ‘gateway drug’ to using others.
  • The CDC claims that about 1 in 10 marijuana users will become addicted. For people who begin using younger than age 18, that number rises to 1 in 6.

4: Cannabis does not have a withdrawal syndrome

“False,” says Dr. Fong. “But why doesn’t the withdrawal syndrome happen with everybody? More research is needed. We view the disorders as not that big a deal, but we see a lot of people coming into our emergency rooms with disturbing behavioural or physiological changes directly after problematic use of cannabis. Often, cannabis use disorder wasn’t the number one reason people go to the ER. It was buried among other symptoms. Physicians’ first thought isn’t cannabis withdrawal when they encounter these. They’ll think: pneumonia, abuse of other drugs, or viral illness. But cannabis-related disorders have been very prevalent in recent years.”

Symptoms that develop within two hours of cannabis use are appetite change, dry mouth, euphoria, and tachycardia (abnormally fast heartbeat).

Other cannabis withdrawal symptoms include:

  • Irritability, anger, or aggression
  • Anxiety
  • Sleep reduction/insomnia and disturbing dreams
  • Appetite changes, weight loss
  • Restlessness
  • Depressed mood
  • Abdominal pain
  • Tremors
  • Fever, chills, headache
  • Sore joints

5: Can cannabis treat other addictions?

Two years ago, Dr. Fong says, he would have definitely said no.

“There’s a wide variety of physical and psychological presentations. We don’t have easy tools that distinguish intoxication from cannabis versus other drugs of abuse. But my mind has changed, like Dr. (Sanjay) Gupta. Maybe there’s a potential there. There’s a research gap, though. We need to know more.”

Challenges and proposed solutions

In citing the challenges faced by medical staff in addressing medical marijuana abuse, Dr. Fong admits that clinicians have very little training in cannabis-related disorders. There is a lack of FDA-approved medications targeted to their management. For now, administration of drugs like buprenorphine, naltrexone, or methadone is the norm, but these are also used to treat other substance use disorders.

There are various therapy treatments but none specifically for cannabis. Even psychotherapy options are similar to those for other addictive disorders. A superior treatment modality has yet to be seen in an institute of medicine.

The 12-Step support groups appear to be leading the way, with the recent introduction of Cannabis Anonymous.

Dr. Fong’s solution is a checklist for clinicians:

  • Screen for cannabis use on every visit.
  • Reverse the thinking of, “It’s not a big deal, no one has died from it.”
  • Explore the relationship with cannabis: distinguish use versus abuse disorder.
  • Explore the impact on mental health.
  • Expand the knowledge base about cannabis and its culture.
  • Restrict cannabis exposure to those aged 2 and above.

As clinicians, he says that they should find answers to these questions:

  • What are the best predictors for treatment success and failure?
  • What are cannabis-specific treatment principles?
  • What is the best prevention strategy?
  • How do we treat cannabis withdrawal?
  • Can there be an effective treatment: medications specific to cannabis, or an electrical device, perhaps?

“Addiction is about avoidance, self-medication, and harm,” Dr. Fong concludes. “If cannabis is reducing your quality of life, then it is problematic.”

It is up to users to decide what they want to do about it.


[1] Wu TC, Tashkin DP, Djahed B, Rose JE. Pulmonary hazards of smoking marijuana as compared with tobacco. The New England Journal of Medicine. 1988, 318:347-51.
[2] Haglage, Abby. “Study on cannabis chemical as a treatment for pancreatic cancer may have ‘major impact,’ Harvard researcher says”. Accessed at on-cannabis-chemical-as-a-treatment-for-pancreatic-cancer-may-have-major-impact-harvard- researcher-says-165116708.html
[3] Maldonado R, Berrendero F, Ozaita A, Robledo P. “Neurochemical basis of cannabis addiction”. Neuroscience. 2011, 181:1–17.
[4] Budney AJ, Hughes JR. “The cannabis withdrawal syndrome”. Current opinion in psychiatry. 2006, 19:233–8.

Photo credit: Damian Gadal. This picture has a Creative Commons attribution license.