A nationally representative survey published in the American Journal of Preventive Medicine finds that 9.4 percent of U.S. adults, roughly 24.1 million people, report having microdosed cannabis in their lifetime. That is nearly twice the rate of psilocybin microdosing and higher than any other substance measured.

Cannabis is also the only substance in the survey microdosed primarily for medical reasons rather than recreational ones.

Most medical conversations about cannabis dosing begin with the question of what dose is therapeutic. This survey reframes it. Tens of millions of Americans have already concluded that sub-threshold doses work for them, and they reached that conclusion without a physician.

When patients do not volunteer that they microdose cannabis, it is often because they assume their physician has no informed guidance to offer. These data make the case that cannabis microdosing belongs on the clinical intake form.

The study, Prevalence and Reasons for Microdosing Cannabis, Psilocybin, LSD, and MDMA Among U.S. Adults, was conducted by researchers at the University of California San Diego and Stanford University and published May 4, 2026 in the American Journal of Preventive Medicine. Kevin H. Yang, MD, of the UCSD School of Medicine Department of Psychiatry, is first author. The team surveyed 1,523 U.S. adults drawn from the Ipsos KnowledgePanel, one of the more methodologically rigorous nationally representative panels available, with survey weights applied to generate national estimates.

The headline finding is clear. Cannabis was the most commonly microdosed substance at 9.4 percent of adults, or about 24.1 million people. Psilocybin followed at 5.3 percent, LSD at 4.8 percent, and MDMA at 2.2 percent. Cannabis did not merely lead. It led by a wide margin.

Clinicians who work in cannabis medicine will not find this surprising. What is surprising is how long it took for population-level data to confirm what practitioners have been hearing in treatment rooms for years. Patients who learn to tune their dose to the lowest effective threshold are, by any reasonable definition, microdosing. Many simply did not have the language for it.

The motivational data are where this becomes clinically actionable. Among cannabis microdosers, 41.2 percent reported doing so for medical purposes, including managing pain. That stands in sharp contrast to the psychedelics measured in the same survey: psilocybin microdosing was recreational 66.6 percent of the time, LSD 59.2 percent, and MDMA 86.0 percent.

The mental health signal deserves careful reading. Across all four substances, lifetime microdosing was more prevalent among respondents reporting poorer mental health. Whether that represents useful self-management or a compensatory response to undertreated illness is not something a cross-sectional survey can resolve. It is a question every clinician working with cannabis patients should hold open.

Microdosing was also more common among people living in jurisdictions that permit recreational cannabis use and have decriminalized psychedelic possession, which suggests that legal environment shapes behavior alongside clinical need.

Cannabis does not follow a simple linear dose-response curve. The relationship between dose and effect in cannabinoid pharmacology is biphasic: at very low doses, anxiolysis and analgesia may appear with minimal psychoactivity, while at higher doses the same patient can experience increased anxiety, sedation, or cognitive disruption. This bell-shaped relationship is one reason clinicians trained in cannabis medicine emphasize starting low and increasing slowly.

Microdosing carries that principle to its logical conclusion. At sub-psychoactive levels, many patients report symptom relief without the impairment that leads others to avoid cannabis altogether. Because the endocannabinoid system maintains tonic signaling activity, even small amounts of exogenous cannabinoids can meaningfully influence receptor tone.

For older patients, microdosing is frequently the most appropriate starting framework. Age-related pharmacokinetic changes, polypharmacy, and fall risk make the lowest effective dose less a preference than a clinical requirement.

The most practically important implication of this survey is the guidance gap it exposes. Roughly 24 million Americans have microdosed cannabis. The number receiving structured clinical guidance while doing so is almost certainly a small fraction of that. Most people exploring sub-threshold dosing rely on online forums, dispensary staff, or personal trial and error.

That is not a criticism of patients. It reflects a medical education system that has not yet integrated cannabis pharmacology into mainstream training. For physicians willing to engage, it is an opportunity. Patients who microdose tend to be motivated, deliberate about their health, and genuinely interested in evidence-based guidance.

They want to know whether what they are doing is safe, whether there is a better way to do it, and whether a different ratio, delivery method, or timing would change their results. Those are answerable clinical questions.

This is strong prevalence evidence and weak causal evidence, and the distinction matters. A nationally representative panel with survey weights and reported confidence intervals is close to the best available design for estimating how common a behavior is. For that question, these numbers deserve confidence.

For any question about whether microdosing cannabis helps, this design can contribute nothing. It measures who reports doing it and why they say they do it. That is the appropriate ceiling on interpretation.

The survey did not apply a standardized operational definition of microdosing specific to cannabis in the way the concept has been formalized for psychedelics. Respondents effectively self-defined the exposure, which introduces real heterogeneity. One person’s microdose is another person’s ordinary dose.

Data were collected in October and November of 2023. The cannabis policy landscape has moved since, so these figures describe a moment that has already passed. Web-based panels also tend to underrepresent populations with limited digital access, and all substance-use reporting carries social desirability pressure in both directions.

This study does not show that microdosing cannabis improves any clinical outcome. It does not identify which protocols, ratios, or delivery methods work best, which conditions respond, or what chronic sub-threshold exposure does over years.

It also cannot establish direction of effect in the mental health association. People with poorer mental health may microdose more, or microdosing may correlate with other factors that track with distress. A cross-sectional snapshot cannot separate those.

Cannabis medicine has spent two decades arguing about whether cannabis works. These data suggest a large share of the public has moved past that argument and on to a more practical one about how to use the least amount that helps. That is a more sophisticated question than the field’s public debate usually credits patients with asking.

It also sits alongside a growing body of work on low-dose and sub-psychoactive cannabinoid effects. Prevalence data of this kind do not settle mechanism, but they do tell researchers and funders that the behavior is widespread enough to warrant properly designed trials.

These numbers match what I see in clinic. Most patients who settle into a stable cannabis routine over time find their way to lower doses than they started with, not higher. That is the opposite of what people expect, and it is one of the most consistent patterns in this work.

What concerns me is not that 24 million Americans are microdosing. It is that most of them are doing it without anyone qualified to answer their questions. A patient who has already decided to take a small amount of cannabis for their arthritis is not asking permission. They are asking for competence. The medical profession should be able to offer it.

Cannabis microdosing is now the most common form of microdosing in the United States, it is primarily medically motivated, and it is happening largely outside clinical supervision. Ask about it directly at intake. Patients rarely raise it unprompted because they assume you have nothing useful to say.

Read this as a map of behavior, not a verdict on efficacy. The finding worth carrying into practice is that a large, medically motivated population is already using sub-threshold cannabis doses and is largely unguided. The finding not to carry forward is any claim that the survey shows microdosing works.