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What is cannabis use disorder?
Cannabis use disorder is the medical term for a pattern of cannabis use that a person cannot reliably control and that causes harm or distress, diagnosed as mild, moderate, or severe by how many of eleven criteria a person meets: using more than intended, wanting to cut down and not managing to, craving, giving up activities, continuing despite problems, tolerance, and withdrawal among them.
Three things make this a live research question rather than a settled one. First, potency: the average THC content of cannabis seized in the US rose from about 4 percent in 1995 to around 15 percent by the early 2020s, and concentrates can exceed 80 percent, so the product being studied is not the product of older research. Second, daily use has risen sharply since 2015 alongside legalization, and daily use is the strongest driver of the disorder. Third, treatment: unlike opioid, alcohol, and nicotine use disorders, cannabis use disorder has no FDA approved medication. Behavioral therapies work for some people, and trials of medicines, brain stimulation, and CBD itself are trying to close that gap. Cannabis use disorder often overlaps with alcohol use disorder, anxiety, depression, and ADHD, and heavy use in adolescence is a recognized risk factor for psychosis and schizophrenia. For the story of why cannabis was so hard to study and what changed in 2026, read our article on 55 years of blocked cannabis research.
Is weed addictive?
Yes, for a meaningful share of people. About 3 in 10 people who use cannabis meet criteria for cannabis use disorder, and the risk is higher for those who start before 18, use daily, or use high potency products. It is less likely to produce dependence than nicotine or opioids, but the idea that it cannot is outdated, and today's products are far stronger than those the old research was based on.
What are weed withdrawal symptoms?
Irritability, anxiety, trouble sleeping and vivid dreams, reduced appetite, restlessness, low mood, and craving, usually starting within a day or two of stopping daily use, peaking in the first week, and easing over two to four weeks. Withdrawal is not medically dangerous but is a main reason people who want to stop return to use, and treatment trials target it directly.
Types of cannabis use disorder clinical trials
Treatment trials. Because nothing is approved, these are the most consequential. Studies test medicines for craving and withdrawal, CBD as a treatment for problematic THC use, psilocybin assisted therapy, and brain stimulation methods such as TMS and tDCS, usually alongside counseling.
Behavioral treatment trials. Cognitive behavioral therapy, motivational enhancement, contingency management, and programs for adolescents and young adults, where the disorder is most common and most treatable.
Cannabis effects studies. Experimental studies in which adults who already use cannabis receive it, or receive THC or CBD, under medical supervision so researchers can measure effects on sleep, memory, attention, mood, driving, and stress. These are not treatment studies; they exist because modern cannabis has barely been studied under controlled conditions.
CBD studies. Trials of cannabidiol for conditions such as anxiety, pain, bipolar depression, and opioid or nicotine withdrawal, and studies of what CBD does in people who use high potency cannabis.
Co-use and dual diagnosis studies. Research on people who use cannabis with alcohol, tobacco, or other substances, and on people with cannabis use disorder and a mental health condition.
Brain imaging, genetics, and observational studies. How cannabis affects the developing brain, who is genetically at risk, and how use and the disorder change over years. No treatment is given, and eligibility is often broad, including healthy comparison volunteers.
Who can participate in cannabis use disorder clinical trials?
It depends on the kind of study. Treatment trials enroll adults, and sometimes adolescents with parental consent, who meet criteria for cannabis use disorder and want to reduce or stop, confirmed at screening, usually with a urine test. Cannabis effects studies enroll adults who already use cannabis regularly and are not asked to quit; they typically exclude people with certain heart or psychiatric conditions and sometimes require a specific frequency of use. CBD trials enroll people with the condition being studied, with or without cannabis use. Observational and imaging studies often accept both people who use cannabis and people who never have. Because trials use randomization and screening, meeting the description does not mean a place is certain; the study team confirms eligibility and explains what each group receives. Eligibility always varies by study.
Considering volunteering in a clinical trial? Explore our comprehensive guide to learn more about why people choose to volunteer and the impact you can make in advancing medical research. Discover the process of volunteering, what to consider before applying and the potential benefits and risks involved.
How cannabis use disorder is described, and why it matters for trials
There are no stages. Clinicians describe the disorder as mild (2 to 3 of the eleven criteria), moderate (4 to 5), or severe (6 or more), and they note how often a person uses, since daily or near daily use drives most of the harm. Treatment trials usually enroll moderate to severe disorder; effects studies specify a frequency, such as weekly or daily use; adolescent studies have their own age bands. Knowing roughly how often you use and whether you have tried to cut down tells you at a glance which studies fit.
Is there compensation for taking part?
Some studies offer compensation for time and travel, and study related care is typically provided at no cost as part of a clinical trial. In cannabis effects studies, the cannabis, THC, or CBD used is supplied by the study under federal licensing, never brought by participants. Compensation varies by trial and is always described during the informed consent process before you agree to anything.
Curious whether clinical trials pay participants? Here's how compensation actually works.
How to find and enroll in a cannabis use disorder clinical trial
Identify your study. Use the filters to search cannabis, marijuana, or cannabidiol. Titles usually say what kind of study it is: a treatment for the disorder, an effects study in people who use cannabis, or a CBD trial for another condition.
Check the setting. Effects studies happen in a lab with supervised sessions, sometimes overnight. Treatment trials mix clinic visits with phone or app follow up. The details say how many visits and whether urine testing is part of the study.
Complete the health profile. Click "Get started" to begin the 5-step application. Have three things ready: how often you use cannabis and in what form, whether you want to reduce or stop, and any other health conditions and medicines. Your information is protected under research privacy rules.
Submit the application. A study coordinator reviews it and contacts you. Nothing is decided until you have gone through informed consent, participation is voluntary at every step, and joining does not require leaving your own doctor.