Kratom Research

How much human research on kratom actually exists?

Very little, and it’s countable.

ClinicalTrials.gov is the federal registry where human trials are recorded. Searching it for kratom returns fifteen studies. Eight are based in the United States, six are based elsewhere, and one lists no location. Four are complete. One was terminated. Four are recruiting. One is running and closed to new participants. Three have not begun. Two have not reported their status in some time.

The enrollment numbers are the part worth sitting with. Fifteen people in the Washington State University drug interaction study. Sixteen in its follow-up. Twenty-two in the Johns Hopkins observation study. Forty in the FDA pilot. Thirty-two planned in the NIDA phase 1, which has not started recruiting.

One Johns Hopkins study meant to characterize commercial kratom extract products was terminated after two people enrolled.

The one large study is different in kind. NIDA ran a real-world assessment of 396 people, with assays run on the products they were actually consuming. Nobody gave them anything. It observed what people already do.

So the honest summary is this. A handful of small controlled trials. One large observational study. And a great deal of survey work. That’s the evidence base every confident claim about this plant rests on.

Has the government run its own study on kratom?

Yes, one, and it’s published.

FDA sponsored a pilot trial of botanical kratom in people. It ran from August 16, 2023 to January 23, 2024 and is registered as NCT06072170. Forty recreational polydrug users took part, in five groups of eight, six on kratom and two on placebo in each group. The kratom used was a single-source encapsulated leaf powder with alkaloid levels representative of leaf products, and 7-hydroxymitragynine at trace levels.

The study stepped the amount up one group at a time. The first group took 1 gram. Later groups took 3, 8, 10 and 12 grams, each step cleared only after a safety review of the one before it. Everyone ate a high-fat meal first, and nobody went through more than one round. The 12 gram group swallowed 24 capsules inside five minutes.

No deaths and no serious adverse events occurred among the forty participants. Sleepiness, vomiting and nausea were the most common adverse events, reported by some participants and not by everyone who took part. At 3 grams and above, kratom constricted the pupils, an opioid-like effect. At 12 grams it raised scores on several measures of how much participants liked the drug and felt high, effects the authors describe as commonly associated with drugs of abuse. The authors also note that the results may not be representative of other kratom-containing products.

The results appeared in the Journal of Clinical Psychopharmacology, volume 46, issue 4, pages 386 to 398, in the July and August 2026 issue. The lead author is an FDA pharmacologist. Among the co-authors is Christopher R. McCurdy of the University of Florida, whose research DEA cites in its own 2026 filings.

Who took part is worth knowing, because it shapes what the numbers mean. The study protocol required participants to be healthy and not dependent on anything, and to have used opioid drugs for non-medical reasons at least 10 times in their life and at least once in the 12 weeks before screening. They also had to have used at least two perception-altering or stimulant drugs on at least five occasions. This is the standard population for an abuse-potential study, because the question being asked is whether a substance produces the kind of experience someone would seek out again. It is not the same as testing the general public, and the paper calls itself a pilot built to shape the larger trial that followed.

One thing to know if you go looking. FDA’s own kratom page has not caught up. As of the version carrying a December 2, 2025 date, it says the manuscript has been submitted and that results will be released once a journal accepts it.

What has the National Institute on Drug Abuse done?

It has funded the university research, and in 2026 it opened the way to a clinical trial of one of kratom’s alkaloids as a drug candidate.

NIDA is the arm of the National Institutes of Health that funds drug research. It has backed kratom work at the University of Florida College of Pharmacy since 2018, under grants including UG3DA048353 and R01DA047855, covering the plant’s chemistry and the pharmacology of its alkaloids. Those grants are searchable by number in the NIH RePORTER database.

June 1, 2026. NIH announced that its investigational new drug application for mitragynine had taken effect with FDA. That clears the way for an NIH-led phase 1 clinical trial to evaluate mitragynine as a drug candidate in opioid use disorder. NIH and University of Florida researchers developed the purified mitragynine formulation used in it, and did the preclinical work behind the application. NIDA director Nora Volkow, M.D., said in the announcement, “This IND is a major step toward expanding treatment options for the millions of Americans struggling with opioid use disorder, which has contributed to historically high overdose mortality rates.”

Read that one carefully, because it’s easy to misread in both directions.

An investigational new drug application taking effect is permission to run a trial. It is not an approval, not a finding of safety, and not a finding that anything works. A phase 1 trial tests safety and tolerability in a small number of people, and it is the first of several stages.

The trial also does not study kratom. It studies a purified, single-alkaloid formulation made under pharmaceutical conditions. That’s a different thing from leaf sold in a package, and the government drew that line itself.

What has the government’s own field research found?

One example is worth walking through, because it shows how careful a real finding is.

Researchers at the NIDA Intramural Research Program and several universities looked at bedtime kratom use. They took a fifteen-day study of 357 US adults who reported what they consumed and how they slept. On it they ran a secondary analysis. The question they asked was whether using kratom at bedtime was associated with better or worse sleep.

Participants used kratom at bedtime on 23.4 percent of days. On those days they reported modest increases in sleep duration and quality. The study did not find bedtime use associated with worse sleep.

Now read what the authors themselves say about it, because that is the part nobody quotes.

It is observational. It cannot establish cause. Sleep was self-reported rather than measured, and most of the questions were written for this study rather than taken from validated scales. The sample came from Reddit, Facebook, the American Kratom Association, vendors and podcasts. So it’s people already committed to the product. 91 percent were non-Hispanic White. Most were long-term users. No product type or amount was recorded for bedtime use. Nothing controlled for caffeine, alcohol, cannabis or sleep medication. Fifteen days is fifteen days. The authors call for controlled laboratory trials in people who have never used kratom. That’s a plain statement that the question is open.

The paper states its conflicts and funding in full. One author disclosed that in the past three years she had served as a paid scientific advisor to the International Plant and Herbal Alliance and as an expert witness in legal cases involving kratom. The other authors declared no conflicts. The work was funded by the NIDA Intramural Research Program, by NIDA grant DA055571 and by National Institute of Neurological Disorders and Stroke grant R01NS129887. It’s normal, it’s why disclosures exist, and it’s the kind of thing to read before the abstract.

That’s what a real finding looks like. Small, hedged, and surrounded by conditions. Anyone selling you a cleaner version of it is selling you something.

What happens when the industry funds the research?

It happens, it’s disclosed, and you should know which studies it applies to.

Of the fifteen registered studies, four list a company as the lead sponsor. Two are sponsored by a company that sells a kava and kratom drink, and both study its own product. A third, testing formulations containing mitragynine, was completed in October 2025 and had posted no results when we checked. The fourth is the contract research company listed as sponsor of the FDA pilot above, which shows that a registry’s sponsor line and the party behind a study are not always the same. A company funding research into its own product is the ordinary state of affairs across every consumer industry.

What it means for you is narrow. A sponsor does not make a result wrong. It makes the sponsor a fact you weigh alongside the result, the same way you weigh who paid for a lab report. That’s the same reasoning we apply to our own kratom lab testing, and to the lab tested kratom reports we publish.

The reason we raise it here is that industry-funded work travels further than university work. It gets a press release. University research usually gets a paper.

What does a published trial not prove?

That the thing it studied is safe. A published trial reports what happened to the people in it.

There’s a useful example in circulation. A 2026 randomized trial in Therapeutic Drug Monitoring reported on 116 volunteers. Forty-nine were given dried kratom leaf powder and 67 were given placebo. It ran escalating single amounts, then fifteen daily amounts over 47 days. Its stated conclusion is that the product was “safe and well tolerated at the dose ranges tested, with no evidence of meaningful abuse potential or withdrawal.”

Two things about that conclusion before anyone repeats it to you.

First, who paid. The paper states that the study was funded by NP Pharma and that all its authors were compensated for study design input, data analysis or publication. That statement sits partway through the discussion, not under a heading of its own, which is why it gets missed. Second, where it was registered. The trial was approved by an institutional review board and by Health Canada, and it does not appear in the ClinicalTrials.gov registry under kratom or under mitragynine.

We’re not saying the trial is wrong. We have no basis for saying that. We’re saying a favorable conclusion in a journal is a starting point for questions rather than an answer to them. The first question is always who paid, and where it was registered.

It is also routinely confused with the FDA pilot above. They’re different studies, with different sizes and different designs. If you see the 1 to 12 gram steps attached to this one, somebody has merged the two. This trial gave between half a gram and 4 grams of leaf powder.

For our part, we don’t say kratom is safe. We’re not permitted to, and we wouldn’t anyway. What can honestly be said on that question is on our page asking Is Kratom Safe? What we publish on Responsible Kratom Use runs in the other direction on purpose.

What has not been studied at all?

More than has. A finding of nothing is a finding, and these are the useful ones.

No trial has compared vein colors in people. Not one. The names on the package have never been tested against each other in a controlled human study, and recent chemical analyses do not show meaningful differences between them. That subject sits on our page about kratom strain names.

The claim that small amounts and large amounts act in opposite directions has no systematic data behind it. That is not our opinion. It is stated directly by researchers who study the plant.

Long-term use in people has no controlled data behind it either. The observational work follows people for days and weeks, not years.

And most of the pharmacology work uses a purified or isolated alkaloid rather than leaf. A study of one compound made under laboratory conditions is not a study of a package of powder. It’s the single most common error in how kratom research gets reported. The government drew that line itself in the NIH announcement above.

What the leaf actually holds, and why an isolated alkaloid behaves differently, is on our page about kratom alkaloids.

How do you read a kratom study without being fooled?

Five questions, and they take about a minute.

1. What did it actually give people? Leaf powder, an extract, or a purified single alkaloid. These are three different subjects.
2. How many people? Fifteen is a signal to look at. Fifteen is not a finding about a population.
3. Who was in it? The FDA pilot recruited people with prior non-medical opioid experience, because that is who an abuse-potential study needs. That’s not the general public, and the paper says so.
4. Did it observe or did it assign? An observational study can show that two things occur together. It cannot show that one caused the other, and its authors will tell you that if you read past the abstract.
5. Who paid, and where is it registered? Both answers are usually one click away. When one of them is missing, that’s itself information.

Every claim you will read about this plant is downstream of those five answers. The same five questions work on a vendor’s marketing, which is the subject of our page on choosing a kratom vendor.

What we will not tell you research shows

Anything about what kratom will do for you.

We report that a study exists and what it set out to find. We name what it gave people. We don’t report a hoped-for answer. And we don’t attach a sentence afterward that closes the loop the study left open.

That rule binds hardest where the research is moving fastest. Trials touching dependence and opioid use are real. They’re registered. One of them is federally sponsored. We will tell you those trials exist and what question they were built to ask. We will never tell you what kratom does for anyone’s dependence, because that is a claim about a product and a body, and no trial anywhere has established it.

One more thing, recorded because it circulates constantly. The idea that a large amount of kratom causes vomiting which then caps how much anyone can take, sometimes framed as a natural ceiling, has no source. We looked. It appears on vendor pages and treatment-center pages, and nowhere else. Do not rely on it.

Where federal agencies stand on the plant, as opposed to what the science says, is on our page about whether kratom is legal federally. What the trade body funding some of this work is, and what it can and can’t do, is on our page about the American Kratom Association.