Some people say cannabis helped them drink less or use fewer opioids. This article looks at what that claim is based on. Most of it comes from surveys and from a single report about one patient, published in 1970. Treatments for alcohol and opioid dependence already exist, and some of them have been shown to reduce deaths. Those treatments come first. Cannabis is, at most, a question to raise with the doctor managing the case.
Safety notice: read this first.
- Alcohol withdrawal can kill. Severe withdrawal can cause seizures (fits) and delirium tremens, a dangerous state of confusion, shaking and agitation. It needs medical treatment.
- Do not try to stop heavy drinking by switching to cannabis, or to anything else, without a doctor’s supervision.
- Opioid withdrawal itself is rarely fatal. The danger comes later. During a break from opioids the body loses its tolerance. If the person goes back to using, the risk of overdose rises sharply. This is why detox on your own is more dangerous than it feels.
- Nothing here is medical advice. It does not replace a conversation with a doctor or an addiction treatment service.
1. What the Claim Is Based On
The traditional claim is that cannabis eases withdrawal from alcohol and from opiates (drugs made from opium, such as morphine and heroin). It is said to ease both the physical and the psychological effects. The clinical evidence for this is very thin.
The source quoted most often is Tod Mikuriya, a psychiatrist in the United States. In 1970 he described one patient who used cannabis to cut down on alcohol (Mikuriya, Medical Times, 1970). This is a case report: a description of a single patient with no comparison group. No controlled trial has ever repeated it. A controlled trial compares a treated group with an untreated group under the same conditions.
So the core evidence is one clinician’s report about one patient, more than half a century old. Older sources also exist. European medical writing from the 1800s mentions cannabis for delirium tremens in heavy drinkers and as a substitute for opium. These are real historical documents. They show what doctors tried before controlled trials existed. They do not show that it worked.
A comparison often made next to these sources is broadly correct. The US Centers for Disease Control and Prevention (CDC), the national public-health agency of the United States, estimates about 178,000 deaths per year from excessive alcohol use. This is the 2020–2021 average from the CDC’s Alcohol-Related Disease Impact application. By contrast, there is no recorded fatal overdose from cannabis alone.
The two figures do not measure the same thing. The alcohol estimate also counts long-term disease and injuries, not only poisoning. Even so, the gap in direct toxicity is real. But this comparison only shows how poisonous each substance is. It does not show that cannabis treats dependence on alcohol.
What to do: When someone quotes the 1970 case or the CDC figure as proof that cannabis treats addiction, check what kind of evidence it is. It is one patient, a historical record, or a toxicity comparison. None of these is a treatment trial.
2. Alcohol Withdrawal: The Fact to Act On First
Nobody disputes this point. Severe alcohol withdrawal without treatment can kill, mainly through seizures and delirium tremens. These deaths can be prevented with withdrawal management under medical supervision.
Alcohol withdrawal is a medical condition with an established treatment. Doctors usually give benzodiazepines, a group of sedative medicines, in a supervised setting. They also give thiamine (vitamin B1). Thiamine prevents Wernicke’s encephalopathy, a serious brain disorder caused by a lack of thiamine.
A person in severe alcohol withdrawal needs a doctor, not a plant. There is little time to make that decision.
What to do: Someone may tell you they drink heavily every day and want to stop. The most useful thing you can say on a forum is: speak to a doctor before you stop, not after.
3. Opioid Withdrawal and Substitution Therapy in Plain Words
Opioids include heroin, morphine and opioid painkillers. A person who is dependent on opioids goes through withdrawal when they stop. Common symptoms include muscle aches, sweating, diarrhoea, anxiety, poor sleep and strong craving. With heroin, symptoms usually start within 8–24 hours of the last dose. With methadone, they start later, after one to three days. On its own, opioid withdrawal is rarely fatal.
The bigger danger is loss of tolerance. During a period without opioids, the body loses its tolerance to them. If the person then takes the dose they used before, they can overdose. This is why stopping alone and then going back to the drug is so risky.
Substitution therapy, also called opioid agonist therapy, works on a different principle. The person takes a prescribed opioid medicine, usually methadone or buprenorphine, at a steady dose under medical supervision. “Agonist” means the medicine acts on the body in the same way as the opioid it replaces. The dependence remains. But a risky, uncontrolled drug habit is replaced by a controlled one with a much lower risk of death. Section 5 shows how much this reduces overdose deaths.
What to do: If someone you know uses opioids and wants to stop, the safer path is to see a doctor and ask about methadone or buprenorphine. Stopping alone, without that support, is not the safer path.
4. What “Substitution” Evidence Actually Exists
The modern version of the argument is not about withdrawal. It is about substitution: people use cannabis and, as a result, use less of something more harmful.
One of the largest recent data sets comes from the New Zealand Drug Trends Survey, an online survey of people who use drugs in New Zealand. Its 2020 round had 23,500 respondents. Researchers Wilkins, Romeo, Rychert and Graydon-Guy analysed it in “Exploring the substitution of cannabis for alcohol and other drugs among a large convenience sample of people who use cannabis”, Harm Reduction Journal 2024;21:192 (DOI: 10.1186/s12954-024-01111-w).
The table shows answers from cannabis users who also used each of the other substances:
| Substance | Reported effect of cannabis use |
|---|---|
| Alcohol | 60% reported drinking less |
| Synthetic cannabinoids | 60% reported using less |
| Morphine | 44% reported using less |
| Methamphetamine | 40% reported using less |
| MDMA, LSD, cocaine | ~70% reported no impact (68–73%) |
| Tobacco | About one-third reported smoking less; 22% reported smoking more |
The limits of the survey matter as much as the numbers:
- How people were found: The survey was promoted through Facebook advertising. That makes it a convenience sample, meaning the people who chose to answer. It was not a group selected to represent all cannabis users.
- Self-report: All answers were self-reported. People may remember wrongly (recall bias) or give the answer that sounds better (social-desirability bias).
- Too few opioid users: Only a small share of respondents had recently used morphine or heroin. So the survey could not properly analyse whether cannabis replaced opioids.
- Opinion, not cause: Most importantly, the survey measures perceived influence, not cause and effect. Asking people whether cannabis made them drink less is not the same as measuring whether it did.
The researchers’ findings describe associations, meaning two things that occur together, and what people believe influenced them. The survey was cross-sectional: a single snapshot taken at one point in time. A single snapshot cannot show which change came first.
There is still a real signal here. Sixty per cent is a large figure. The pattern also matches what clinicians hear from patients. But this is exactly the kind of finding that a randomised trial is designed to test. In a randomised trial, chance decides who gets the treatment and who gets the comparison. Any difference in results can then be credited to the treatment. No randomised trial has tested cannabis as a substitution treatment for alcohol or opioid use disorder with clinical endpoints, meaning measured health outcomes rather than opinions.
What to do: When you read a survey percentage, check three things. Who was asked? How were they found? Did the study measure a cause, or only what people believe?
5. Treatments With Evidence on Deaths
Any substitution argument has to be compared with the treatments that already exist. Cannabis falls far behind.
For opioid use disorder, opioid agonist therapy has measured effects on deaths. A research team led by Larochelle studied 17,568 adults in Massachusetts, a US state, who had survived an opioid overdose (Annals of Internal Medicine, 2018). The team followed them for twelve months. People on methadone had 59% fewer opioid overdose deaths than people on no medication. People on buprenorphine had 38% fewer.
The same study found a second problem. Fewer than one third of patients received any medicine for opioid use disorder in the year after their overdose. Methadone went to 11%, buprenorphine to 17% and naltrexone to 6%.
These two findings belong together. Treatments that cut overdose deaths by 38–59% exist, yet most people who need them do not get them. That gap is the biggest failure in opioid care. The lack of cannabis is not.
For alcohol use disorder, approved medicines exist: naltrexone, acamprosate and disulfiram. They are used together with psychosocial treatment such as counselling and support. Supervised withdrawal management is available for people who need it.
Cannabis has nothing comparable. No randomised trial has tested cannabis as a substitution treatment for alcohol or opioid use disorder with clinical endpoints. Randomised trials of single cannabinoids do exist. They are small, early-stage studies:
- Hurd and colleagues (American Journal of Psychiatry, 2019) gave cannabidiol (CBD) or a placebo (a dummy treatment) to a small group of people with heroin use disorder. All were drug-free at the time. CBD reduced anxiety and craving triggered by drug-related cues. This was an exploratory trial. It did not measure treatment outcomes.
- Bisaga and colleagues (Drug and Alcohol Dependence, 2015) tested dronabinol, a synthetic form of THC. Patients took it during opioid detox in hospital. It made withdrawal less severe. It did not raise the number of patients who started or stayed on extended-release naltrexone, a long-acting form of a medicine that blocks the effects of opioids.
Neither study measured overdose or death.
The closest thing to data on deaths comes from ecological studies. These compare whole states, not individual patients. They show the gap between association and cause very clearly.
- Bachhuber and colleagues (JAMA Internal Medicine, 2014) looked at 1999–2010. US states with medical cannabis laws had about 25% fewer deaths from opioid painkiller overdose than states without such laws.
- Shover and colleagues (PNAS, 2019) used the same method and extended the data to 2017. By then the link had reversed. States with medical cannabis laws had about 23% more opioid overdose deaths.
Shover’s team concluded that the link was most likely spurious, meaning it was not a real cause-and-effect relationship. State-level data cannot show what individual people did. Here the same method gave opposite answers a few years apart.
What to do: If a post claims that cannabis laws reduce overdose deaths, reply with both studies. For a person with opioid use disorder, the first step backed by evidence is asking a doctor about methadone or buprenorphine.
6. The Risk in the Other Direction
Substitution only reduces harm if two things are true. The substitute must be clearly less harmful, and the person must actually use less of the original substance.
Cannabis use disorder is real. Bahji and colleagues ran a meta-analysis, a study that pools the results of many earlier studies (JAMA Network Open, 2020). It covered 47 studies and 23,518 regular or dependent cannabis users. 47% had cannabis withdrawal syndrome. Symptoms included irritability, anxiety, poor sleep, changes in appetite and physical symptoms. They usually appeared within about a week of stopping.
This does not make substitution pointless. Swapping a dependence with a high death rate for one with a much lower death rate is a real gain. The same reasoning explains why opioid agonist therapy works. But the honest description is trading one dependence for another with a different set of risks. It is not “getting clean”. Anyone considering this should be told so plainly, not find out later.
The tobacco row in the survey shows that substitution can go the wrong way. About one in five people who used both cannabis and tobacco (22%) said they smoked more tobacco.
What to do: If you use cannabis to cut down on something else, write down how much you use of each substance every week. This record shows whether you are really using less of the original substance. Also note any irritability, poor sleep or appetite change on days without cannabis. These are signs of dependence that you should mention to your doctor.
7. A Fair Position on the Evidence
- The question is legitimate. Harm reduction means lowering the damage from drug use, including when the person cannot stop yet. It is a serious clinical discipline, and substitution is one of its main tools. Asking whether cannabis could play that role is a reasonable question, not a fringe one.
- The evidence is at survey level. It consists of people’s own views of what influenced them, collected from convenience samples. It also includes state-level data that has pointed both ways. No randomised trial has tested cannabis as a substitution treatment for alcohol or opioid use disorder with clinical endpoints.
- Cannabis must not replace what works. This matters most for opioid use disorder. Delaying or refusing agonist therapy in favour of cannabis means giving up a treatment that reduces deaths. In return the person gets a treatment with no proven benefit. The same error happens when a patient declines proven cancer treatment in favour of cannabis, and the arithmetic is the same.
- Using cannabis alongside a supervised treatment plan is a separate question. The clinician managing the case should answer it. Only the clinician can weigh it against everything else the patient is taking.
What to do: If you are thinking about cannabis while cutting down, raise it with the doctor who is treating you. Bring a list of every medicine and substance you use, so the doctor can check how they interact.
8. In Thailand
Translator’s note: Cannabis flower (ช่อดอกกัญชา) is a controlled herb under the Notification of the Ministry of Public Health Re: Controlled Herbs (Cannabis), B.E. 2568. This notification was issued under the Thai Traditional Medicine Protection Act B.E. 2542 and came into force on 26 June 2025. Flower may be sold only against a prescription on form PT 33 (ภ.ท.33), covering no more than 30 days. Advertising and online sale of flower are prohibited.
Translator’s note: Substance use disorder is not one of the conditions for which medical cannabis has an evidence base. A prescriber considering it would be weighing an unproven benefit against a known risk of dependence. A past history of substance misuse is itself a reason for particular care.
Translator’s note: If alcohol or drugs are a problem for you or someone close to you, call the 1165 helpline. It is run by the Princess Mother National Institute on Drug Abuse Treatment (PMNIDAT), also known as the Thanyarak Institute. The helpline gives advice on drug and alcohol problems and on where to get treatment. Your doctor or local hospital is the other place to start. The medicines described in section 5 are real medicines with real evidence behind them. Methadone treatment is offered in Thailand. Ask the doctor which of the other medicines are available to you. Either option is a better first call than a forum. If you live far from a hospital, book the appointment before you stop drinking. Do not wait until withdrawal starts.
Translator’s note for licensed shops and farms: Do not present cannabis as a treatment for alcohol or opioid dependence, whether in posts or at the counter. The evidence does not support this claim, and advertising flower is prohibited in Thailand. If a customer says they want to stop heavy drinking or opioid use, give them the 1165 number and advise them to see a doctor first.
Share your experience below: Perhaps you have cut down on drinking or opioid use and believe cannabis played a part. If you post about it under this topic, also list what else changed at the same time, such as a job, a relationship, a treatment programme or a move. Substitution studies cannot separate these factors. Accounts that name them are more useful here, because personal testimony on its own cannot show cause and effect. Questions are welcome in the replies too.
This article is published by the Asiannabis Community for educational purposes. It is general information, not medical advice, and it is not a treatment protocol for any substance use disorder. Never attempt unsupervised withdrawal from alcohol.
References
- Mikuriya TH. Cannabis substitution: an adjunctive therapeutic tool in the treatment of alcoholism. Medical Times, April 1970, pp. 187–191.
- US Centers for Disease Control and Prevention. Alcohol-Related Disease Impact (ARDI) application: deaths from excessive alcohol use, 2020–2021 average.
- Wilkins C, Romeo JS, Rychert M, Graydon-Guy T. Exploring the substitution of cannabis for alcohol and other drugs among a large convenience sample of people who use cannabis. Harm Reduction Journal 2024;21:192. DOI: 10.1186/s12954-024-01111-w.
- Larochelle MR, et al. Medication for opioid use disorder after nonfatal opioid overdose and association with mortality: a cohort study. Annals of Internal Medicine 2018;169(3):137–145. DOI: 10.7326/M17-3107.
- Hurd YL, et al. Cannabidiol for the reduction of cue-induced craving and anxiety in drug-abstinent individuals with heroin use disorder: a double-blind randomized placebo-controlled trial. American Journal of Psychiatry 2019;176(11):911–922. DOI: 10.1176/appi.ajp.2019.18101191.
- Bisaga A, et al. The effects of dronabinol during detoxification and the initiation of treatment with extended release naltrexone. Drug and Alcohol Dependence 2015;154:38–45.
- Bachhuber MA, Saloner B, Cunningham CO, Barry CL. Medical cannabis laws and opioid analgesic overdose mortality in the United States, 1999–2010. JAMA Internal Medicine 2014;174(10):1668–1673. DOI: 10.1001/jamainternmed.2014.4005.
- Shover CL, Davis CS, Gordon SC, Humphreys K. Association between medical cannabis laws and opioid overdose mortality has reversed over time. PNAS 2019;116(26):12624–12626.
- Bahji A, Stephenson C, Tyo R, Hawken ER, Seitz DP. Prevalence of cannabis withdrawal symptoms among people with regular or dependent use of cannabinoids: a systematic review and meta-analysis. JAMA Network Open 2020;3(4):e202370. DOI: 10.1001/jamanetworkopen.2020.2370.