Clearing the Haze – Is Marijuana Addictive?

In the past few years, as addiction researchers have been mapping out the chemical alterations in the brain caused by alcohol, nicotine, methamphetamine, and other drugs, America’s most popular illegal drug has remained largely a scientific mystery. It is a drug that millions of Americans have been using regularly for years, and, from a clinical perspective, it remains the least studied illicit drug of all.

The most popular, and the least studied — not a prescription for rational decision making from a public health point of view. A variety of influences combined to force marijuana research off the table years ago, but the birth of “receptorology,” as molecular scientist Candace Pert once called it, and a more relaxed grip on federal funding has refueled the research.

Why did cannabis research lag behind that of other drugs of abuse? For decades, the prevailing belief among users and clinical researchers alike was that marijuana did not produce dependency and therefore could not produce major withdrawal symptoms. Nonetheless, heavy marijuana users were claiming that tolerance does build. And when they withdraw from use, many report strong cravings. Marijuana withdrawal, which typically affects only heavy smokers, has not been well characterized by the research community.

Back in the fall of 1988, pharmacology professor Allyn Howlett and her colleagues at St. Louis University Medical School came up with strong evidence for the specific brain receptor to which the THC molecules were binding. However, the nature of the organic chemical itself — the compound in the brain that was meant to bind to those reported sites — remained unidentified until 1992. That year, William A. Devane, one of the researchers at Hebrew University in Jerusalem, along with Rafael Mechoulam and others, identified the body’s own form of THC in pulverized pig brains. The substance that stuck to the THC receptors was known as arachidonyl ethanolamide. Devane christened the substance “anandamide,” after the Sanskrit ananda, or bliss. It was left for animal physiologist Gary Weesner of the U.S. Department of Agriculture (USDA) to ask the burning question: “How do pigs use their anandamide?” In a study of the possibility of using anandamide as a safe sedative for animals, Dr. Weesner discovered that pigs treated with anandamide tended to show lower body temperature, slower respiration, and less movement — all indicators of a calmer porcine state of mind.

THC and its organic cousin make an impressive triple play in the brain: They effect movement through receptors in the basal ganglia, they alter sensory perception through receptors in the cerebral cortex, and they impact memory by means of receptors in the hippocampus. However, there has been little evidence in animal models for tolerance and withdrawal, the classic determinants of addiction. To the early researchers, it did not look like cannabis should be addictive. And for at least four decades, million of Americans have used marijuana without clear evidence of a withdrawal syndrome.

Nevertheless, some people appear to exhibit a classic pattern of dependency. By the year 2000, more than 100,000 Americans a year were seeking treatment for marijuana dependency, by some estimates. Marijuana Anonymous, an organization modeled on the principles of Alcoholics Anonymous, had become a robust recovery organization. What was going on?

Some of the mystery of marijuana’s effects was resolved after researchers demonstrated that marijuana definitely increased dopamine activity in the limbic area of the brain, as do all other addictive drugs. Tanda, Pontieri, and Di Chiara demonstrated that dopamine levels in the nucleus accumbens doubled when rats received an infusion of THC. It appears that marijuana also raises dopamine and serotonin levels through the intermediary activation of opiate and GABA receptors.

In 2004, a study group at the University of Vermont undertook a critical review of all major relevant studies of marijuana withdrawal. The meta-review appeared to bear out the theory that there are heavy marijuana users who suffer a verifiable and often vivid set of withdrawal symptoms when they try to quit. The most common clinically significant symptoms of abrupt withdrawal in heavy pot smokers, according to the research group, were

anxiety, decreased appetite/weight loss, irritability, restlessness, sleep problems, and strange dreams. These symptoms were associated with abstinence in at least 70% of the studies in which they were measured. Other clinically important symptoms such as anger/aggression, physical discomfort (usually stomach related) depressed mood, increased craving for marijuana, and increased sweating and shakiness occurred less consistently.

These are not trivial issues. As one long-time heavy cannabis user put it: “It’s not suicidal ideation but it’s the feeling that life will just never ‘be right’… when you suffer from symptoms that you’ve been told don’t exist, you are left looking for the wrong cause. So, if you’re told that marijuana withdrawal does not increase anxiety, anger, or ‘hopelessness,’ you want to look for a cause of those things… I went through withdrawal periods where I was inappropriately angry at the wrong thing, thinking that specific people were upsetting me when they were not.”

In the final post of this series, we will hear from more heavy marijuana users, in their own words. Personal observations and selected case histories of frequent marijuana users were gathered from anonymous, unedited comments posted on a blog site maintained by the author.


Hanson D. “Marijuana Withdrawal: A Survey of Symptoms.” In The Praeger International Collection on Addictions. Ed. by Angela Browne-Miller. Westport, Connecticut: Praeger, 2009. Vol. 2 pp.111-124.

Budney, A. (2004). Review of the Validity and Significance of Cannabis Withdrawal Syndrome American Journal of Psychiatry, 161 (11), 1967-1977 DOI: 10.1176/appi.ajp.161.11.1967

Kouri, E., & Pope, H. (2000). Abstinence symptoms during withdrawal from chronic marijuana use. Experimental and Clinical Psychopharmacology, 8 (4), 483-492 DOI: 10.1037/1064-1297.8.4.483

Rodriguez de Fonseca, F. (1997). Activation of Corticotropin-Releasing Factor in the Limbic System During Cannabinoid Withdrawal Science, 276 (5321), 2050-2054 DOI: 10.1126/science.276.5321.2050

Tanda, G. (1997). Cannabinoid and Heroin Activation of Mesolimbic Dopamine Transmission by a Common µ1 Opioid Receptor Mechanism Science, 276 (5321), 2048-2050 DOI: 10.1126/science.276.5321.2048

  • If you live in California and favor legalizing marijuana, YOU can make it happen. Tell your representatives to support California Assembly Bill 390. It’s easy. Visit

    • The website you recommended, lead to a website regarding toys. I am against the legalization of recreational use of marijuana, however I was interested in how you were to further your interest.

  • Eric

    Thank you! For one, I am all for the legalization of drugs. With that said, I get upset when people say “marijuana is not addictive.” It is addictive, just like fast food, exercise, sex, etc… However, marijuana addiction is different than fast food, exercise, sex, etc… because you don’t have to work for the high, unlike the others (yes, even with fast food you have to get into your car and drive to McDonalds). People get use to the “easy” high, and thus depend on marijuana to give them that.

  • It would be nice if all drugs get out of the criminal scene. I think that is only effective if it happens all over the world at the same time. Otherwise it just attracts organized crime – like in the Netherlands …
    Having said that, I have seen some pretty damaged brains after use of marijuana (in a scan).
    Also, the marijuana from 30 years ago is not the same as is available now – it is now so much stronger …
    I personally prefer meditation … 🙂

  • Hi

    I run a forum for people who feel they are addicted to marijuana, I hear from people everyday who describe the symptoms listed above when they try to quit. It may not as be severe as the withdrawal from drugs like opiates, but a withdrawal can exist, particularly for heavy users.

  • I would be so interested to see the effects of marijuana withdrawal listed above compared side by side with effects of caffeine withdrawal, just to see things in perspective.

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  • mahu

    yes, as a hippy and way beyond ( if there is one) i was a pot user. My most long time friends considered me an addict although i could not ‘see’ it. I started at 15 yrs old, and continued to this day if it were not for life imprisonment here in Philippines as i have no money for food, thus one starves to death in prison in Philippines, the country that most resembles USA in Constitutional Law and application.
    After being forced into withdrawl, having smoked a single puff on a pipe of the narcotic at 10 PM or 47 yrs, then suddenly forced to stop i found my self irritable, angry, hungry, nervous, bouts of violence. This continued for 3 minutes, more or less, then i never thought about it again. Still, i will never forget the horrors of addiction to pot. I was an addict and this is a STAIN that even Jesus Christ can not disguise in those final days. I ruined my life by this one mistake. Yes, true i think, i have Severe ADHD and i was never given medications and one doctor suggested that i used pot as a ‘home made’ medication to calm my condition that i suffered from desparately all my life, left my family in shambles, distroyed our family, our reputation, put may people in prison, in the hosptial, even making me so called ‘wrong’ in my diagnosis of other illnesses in our family, as we could not afford a doctor so i was the eldest and acted as one, even wore the white coat…still, with all that… i could not med my own people.
    maybe that was part of my pot addiction too, but someone had to become the family doctor…and i went to 10th grade, so why NOT ME? That is what they all said.
    Anyway, without pot, the world would have few problems.

  • Charles M.

    Hello, I am not at all opposed to the idea that marijuana can be addictive for some. However, I have to call into question the statistic reported in this article that over 100,000 Americans sought treatment for marijuana addiction in any year. I have a strong suspicion that this statement neglects to account for the number of court-ordered entrances in rehabilitation, which must be very high given that hundreds of thousands of Americans each year are charged with marijuana possession.

    • Pressingtheisse

      I totally agree, I have not met a single person that went to rehab for pot. I think that if the government scaled down the war on drugs, everyone would be better off. I’m a recovering addict and I know that the drug problem could be dealt with more rationally!

      • Anonymous

        well you can count me as the first then…. I go to a therapist once a week to help me through the fight…. and its hard that most people don’t believe that it can be a struggle… when you get stoned your whole life and finally want to make yourself better and try to get support from family and friends… and can’t because everyone thinks its a joke…. thats not good…. and the people that say its not addictive are probably smoking as they are writing it….or have never been addicted….. I do it for my kids myself my life I want to remember my life…. Sober

        Sober in Colorado

      • I was reading in the Christian Science Monitor, that in Amsterdam, where they had once legalized marijuana, had to repeal the law, because they noticed an increase in prostitution and harder drug sales and use. Also, I was reading another article, that in Vancouver B.C., where 50% of the marijuana is grown for Canada, that there is a program called “insite”, for cocaine and heroine abusers, where the tax paying citizen pays for the cocaine, heroine and a place to inject or use the drug. All at tax payer expense. Just an example, of the symbiosis of the narcotic addict narcissistic self-esteem.

        • Max

          A small percentage of people will get addicted to whatever substance you throw at them. Recreational use in overwhelming majority will never ever lead to any significant problems. But not all substances are equal. The most dangerous, however, are not the illegal drugs, but the legal one – alcohol. It is cheap, easily available, addictive, lethal (see LD50) and is the ONLY legal drug (non-prescription) that will kill you if withdrawal is not treated in the hospital. Given its devastating social and economic impact (e.g. over 30,000 DUI related deaths annually, damage to multiple organ systems with chronic use/abuse, violent behavior, broken families, loss of job etc) it would make a lot of sense to make alcohol illegal. Problem? Prohibition does not work, never did, never will.

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  • Anonymous

    I think that people will become addicted to anything reguardless, for gods sake people get addicted to shopping and food if people are ‘addicted’ to marijahuana its because they have an addictive personality.

  • Nancy, Ojai

    This article fails to mention that many of the so-called “withdrawl” symptoms share many characteristics of concommitant mental illnesses. Patients diagnosed with Bipolar disorder, cyclothymia, ADHD, ADD, and depression frequently display irritability, impulsivity, agitation, anxiety, stomach complaints, and changes in appetite when not on appropriate medication(s). We know many of these patients self-medicate with any number of mind-altering drugs. I think patients who suffer such symptoms when they stop smoking marijuana must be screened for mental illness(es) prior to assuming they are suffering from withdrawl.
    Marijuana is NOT a narcotic (not even close). There are no health problems associated with its use. On the other hand, we know the destruction that a perfectly legal drug, alcohol, wreaks on our society.
    What’s wrong with that picture?

  • Steven

    Marijuana is so less harmful for the public than alcohol. They are both drugs/chemicals.

    As a 20 year marijuana smoker there is no doubt there are withdrawal symptoms, anger was consistently one for me and it was predictable, when I would quit for a week or travel and go on vacation where I couldn’t bring my stash. And not just normal anger, for me it was rage for no valid reason, it was definately the pot withdrawal. Lethargy and sleepiness as well.

    My questions is because there are withdrawal symptoms, does that automatically mean you are addicted. I quit 2 years ago, after smoking it all day everyday for the last 5 years prior to quitting. My family did an intervention and I went to rehab, but never have I had a craving since quitting, not during rehab or ANY time afterwords. But I’m supposed to not drink anything, because one addiction can become another, but am I addicted. Of course the experts say “if you question if you are addicted, that is just your addiction talking”. Though I just read on this side that recent studies have shown that a synthetic form of Kudzu vastly reduces cravings for alcohol. Subjects no longer desired to dram a vast amount. These are Harvard doctors. They say that alcoholism will be treatable like diabetes, where you avoid being hurt by it, but not necessarily cure it. Wow, but who knows, enough rambling for now….

  • maximillion swell

    For the purpose of scientific/addiction discussion, this is a nice article. For the purpose of social/political discussion, compare heavy marijuana users with heavy alcohol users, then compare the outcomes.

    Another interesting point, as stated above – “millions of marijuana users”, and 100,000 seeking help for addiction as of 2000. What is “as of 2000” supposed to mean? What period does that cover? Last 20-30 years? Even if less than that 100,000 addicts (all non-lethal outcome), compared to millions and millions of users over several decades with no addiction symptoms sufficient to seek help? Reason to worry? I don’t think so.

  • I think its fine to be addicted to marijuana. it doesnt have bad effect like alcohols do to our body. I am not addicted to marijuana, my brother does. And I really don;t care, as long as he can pay for it

  • foxglove123

    Well, If it was some years ago, I would just say all those researchs were meant to be social manipulative. But I quit smoking pot about 2 months and a half ago and I have to say that I am REALLY glad I did. I have mostly been destroying my life, my family`s life so far.
    I am very anti social and I guess before it was because of willing to be alone to smoke and right now it might be paranoia. Also smoking marijuana and studying arts it is the biggest mistake I have ever done to the point where I am doubting reality. I cannot socialize very much anymore (living abroad alone might have been also contributing to this) and I am anxious to hell. My organization skills are a flaw. I can`t concentrate at all, cannot express my self, my intellectual skills are vanishing.
    Please, if you are smoking pot, just stop.

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  • Anonymous

    Not everyone can become psychotic as a result of its use nor face addiction. The first question one needs to ask is how much they use, followed by how often and does use cause or result in problems in terms of school, work, family or social life?

    Some people can handle it, while for others inner demons can be brought out such as if exposed to trauma in childhood. Those who have an addictive personality can often wind up adding another vice. It should be noted that dealers make their lively hood selling this stuff and as such are more likely to spray/lace it with something to make consumers return, thus resulting in guaranteed profit. The addition of such chemicals not only increased the chances of addiction and dependence but also remains detrimental to ones health, IE adding comet or Mr Clean can surely mess with the liver and kidneys.

    That being said in its natural state it has a reputation for being an effective painkiller.Recent research has shown that by knocking out the CB1 receptor gene certain negative effects from its use are diminished such as memory problems and so on.

  • Eddie

    Some people can use marijuana safely and it can contribute positively (or at least not too negatively) to their lives. Some people can’t use it safely. I have seen people’s lives (relationships, career, mental health) be adversely affected by marijuana use. If you are looking for help check out the New Life House website. They are the people who helped me.

  • Jon

    Nice article, it was really informative. I used to be a heavy marijuana user and I can say that there are definitely withdraw symptoms that can happen. I also know someone who was formerly addicted to opiates and I can say that what he described sounded a thousand times worse than the few days of queasy stomach and lack of sleep that I experienced. I think marijuana certainly can be addictive for some but it seems like the majority of people only use it on occasion and its never a problem. I forget the statistic But I’ve heard that the vast majority of people in drug treatment for weed are there by court order, many of whom only occasionally imbibed the substance.

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Dirk Hanson, MA

Dirk Hanson, MA, is a freelance science writer and the author of “The Chemical Carousel: What Science Tells Us About Beating Addiction.” He is also the author of ”The New Alchemists: Silicon Valley and the Microelectronics Revolution.” He has worked as a business and science reporter for numerous magazines and trade publications. He currently edits the Addiction Inbox blog, and is senior contributing editor for the addiction and recovery website, The Fix.

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