Why A Death Caused By 7-OH Can End Up Recorded As Mitragynine

Court filings, news reports and state health data increasingly turn on a single line in a toxicology report. That line is less precise than it looks, and the agency now moving to schedule concentrated 7-hydroxymitragynine has said so in its own scientific assessment.

The Food and Drug Administration's Center for Drug Evaluation and Research published an assessment of 7-OH authored by its Controlled Substance Staff and Office of Surveillance and Epidemiology. In a section on the limits of the available data, it makes the point directly: "Many forensic laboratories test for mitragynine as a marker of kratom use. In these cases, 7-OH overdose cases and fatalities may incorrectly be classified as kratom and/or mitragynine-related."

The assessment adds a second complication in the following sentence: "Furthermore, toxicology reports documenting presence of 7-OH are difficult to interpret, because 7-OH is a known metabolite of mitragynine in humans."

Those two sentences describe a measurement gap sitting underneath a large amount of public reporting.

Why Mitragynine Became The Marker

Mitragynine is the alkaloid that laboratories look for when they want to know whether someone used kratom. Labcorp's provider guidance, published June 4, describes mitragynine as "the primary compound targeted in available presumptive (immunoassay) laboratory testing," and states plainly that "the immunoassay does not detect 7-OH directly."

That does not mean 7-OH exposure goes unseen. Labcorp's guidance explains why: its internal evaluation of commercially available 7-OH products, along with published reports, found that "these products commonly contain mitragynine," so "the presence of mitragynine is typically sufficient to produce a positive screen in most cases." The laboratory also reports that it is "not commonly seeing 7-OH detected in isolation without mitragynine" in clinical testing, and that definitive mass spectrometry is available where appropriate.

The distinction that matters is between detecting an exposure and identifying what drove it. A screen keyed to mitragynine can register that a person consumed something kratom-derived. It does not, on its own, establish whether that something was leaf or a concentrated product — and it is the second question that the criminal cases, the civil suits and the federal threshold all turn on.

The Metabolite Problem

Even when a laboratory quantifies both compounds, a further ambiguity remains: 7-OH in a blood sample can come from a product or from the body. The human body converts mitragynine into 7-OH, so 7-OH will be present after ordinary leaf consumption. Finding it does not prove a concentrated product was taken.

What can distinguish the two, in principle, is the ratio between them. Kei A. Osawa and Robert D. Johnson of the Tarrant County Medical Examiner's Office in Fort Worth, Texas, published an analysis of 51 postmortem cases in the Journal of Analytical Toxicology in February 2025, quantifying both compounds across blood, vitreous humor and urine. They reported "large average mitragynine to 7-hydroxymitragynine ratios of 30.9 in femoral blood and 32.4 in heart blood," against lower ratios of 14.8 in vitreous humor and 16.9 in urine.

A roughly thirty-to-one ratio is the ordinary pattern when 7-OH arrives as a metabolite. A markedly different ratio is what would suggest 7-OH was consumed directly. That comparison is only available where a laboratory measured both compounds — which, per the FDA's assessment, many do not.

The Clock Problem

The same study identified a factor that pushes in one direction. Osawa and Johnson tested how the two compounds hold up in storage. Refrigerated at 4°C, they found, "mitragynine was stable for up to 30 days and 7-hydroxymitragynine was stable for up to 7 days" within a 20 percent loss threshold. After 60 days of refrigerated storage, "7-hydroxymitragynine concentrations dropped over 50% from initial concentrations."

Mitragynine, in other words, keeps roughly four times longer than 7-OH under the same conditions. Where specimens sit before analysis — a common circumstance in medical examiner casework — the compound that degrades faster is the one more likely to be under-measured. The direction of that error is not neutral.

Where The Testing Does Not Happen At All

Before any of this applies, a laboratory has to look. An investigation published August 10 by The Current GA found that Georgia medical examiners detected kratom in more than 740 accidental overdose decedents between 2019 and 2025, but that public health officials believe the real figure is higher because "only a handful of Georgia's 159 counties test for kratom alkaloids in standard toxicology screenings." The investigation also reported that many medical examiners in the state are unfamiliar with the concentrated products now on shelves.

Testing capacity, not just testing method, sets what the record can show.

The National Numbers Carry The Same Caveat

The largest recent dataset on kratom-related harm states the limitation in its own text. Writing in the CDC's Morbidity and Mortality Weekly Report on March 26, Eleanor Blair Towers and Christopher P. Holstege and Rita Farah of the University of Virginia, with Ynhi T. Thomas of Baylor College of Medicine, analyzed eleven years of National Poison Data System records. They counted 14,449 kratom exposure reports between 2015 and 2025, with 3,434 in 2025 alone — an increase of approximately 1,200 percent over the 258 reported in 2015.

The authors tie that surge to the products now under federal review, writing that it "coincides with the emergence of high-potency, semisynthetic formulations, including 7-hydroxymitragynine." But among the study's stated limitations is precisely the gap described above: "the data do not include information about whether the kratom use involved traditional leaf products or semisynthetic or concentrated formulations, such as 7-hydroxymitragynine, thereby limiting conclusions about formulation-specific risks."

A second limitation compounds it. Where more than one substance was reported, the authors write, "determining which substance was most related to clinical effects or medical outcome, including death, was not possible." That qualification carries weight at scale: of 233 kratom-associated deaths recorded across the study period, 184 — 79 percent — involved multiple substances, with opioids reported in 62 percent of fatalities, benzodiazepines and stimulants in 20 percent each, and ethanol in 19 percent.

The report's own recommendation follows from the gap. "As FDA moves to regulate 7-hydroxymitragynine but not whole-leaf kratom products," the authors write, "surveillance should distinguish product types to assess risks."

What Researchers And The Industry Say

The measurement question has begun appearing in the literature as a stated limitation. A 2025 review in Pharmaceutical Biology by Scott Alsbrook, George Pro and Igor Koturbash surveyed the 7-OH literature and concluded that concentrated 7-OH products are "pharmacologically and toxicologically distinct from kratom leaf," noting that such products "bypass metabolic formation, producing markedly higher exposures" than leaf ingestion does. The FDA assessment cites work by Kirsten Smith, Edward Boyer, Oliver Grundmann, Christopher McCurdy and Abhisheak Sharma, published in Addiction in 2024, on the rise of semi-synthetic 7-OH products.

The American Kratom Association has argued the categorical version of the point. Announcing its support for the DEA's July 1 action, Mac Haddow, the association's senior fellow on public policy, said that "chemically manipulated 7-OH opioids are not kratom" and that they are "dangerous products that exploited the reputation of natural kratom leaf, misled consumers." That is a trade association's position on the products, reported as such; the association's public materials reviewed for this article do not address forensic testing methodology.

What This Does And Does Not Establish

The uncertainty here runs in both directions, and that is the part most easily lost.

It does not license the assumption that deaths recorded as mitragynine-related were in fact caused by concentrated 7-OH. The FDA assessment is explicit that the inference is hard to make in either direction: because 7-OH "is both a metabolite of mitragynine and naturally present in low amounts in botanical kratom, using toxicology results to identify 7-OH as a primary or sole contributor in human exposures is challenging." A finding that names mitragynine is not secretly a 7-OH finding, and treating it as one would repeat the error in the opposite direction.

Nor does any of this speak to whether kratom leaf is safe. That is a separate question, and this publication takes no position on it. The FDA maintains a general warning to consumers against using kratom.

What the assessment does establish is narrower and consequential: the category labels in the public record are less reliable than the confidence with which they are quoted. Where a case matters — a wrongful-death suit, a state enforcement action, a surveillance statistic cited in support of a rule — the underlying question is whether both compounds were measured, in what ratio, and how long the specimen sat first. Reporting that treats "mitragynine intoxication" as a settled description of what a person consumed is claiming more than the method delivers.