Skip to content
Haven Access
Learn · the science

What 7-OH actually is

7-hydroxymitragynine sits at the centre of nearly every kratom bill written in the last two years, and almost everything said about it in a hearing room is either overstated or out of date — in both directions.

This page is what the published measurements actually show. Every claim is cited, and where the evidence is contested or thin we say so.

Start here

Both a leaf alkaloid and a metabolite

7-OH is an alkaloid that occurs in kratom leaf in trace amounts — often below what a lab can reliably quantify, and highly variable from leaf to leaf. It is also the principal metabolite of mitragynine: when you swallow kratom, an enzyme in your liver converts some of the leaf's main alkaloid into 7-OH.

Both are true at once, and arguments about 7-OH usually go wrong by insisting on only one. It is not a synthetic invented in a lab, and it is not simply "the leaf" either.

A concentrated 7-OH product is more potent than a leaf carrying a trace of it. We are not going to pretend otherwise, and we do not need to. Potency is a labeling problem, not a prohibition trigger. The answer to a strong product is to say on the outside of the package exactly how strong it is, test every batch, and sell it to adults — which is what Section 13 of our model act requires, and what it rules out doing instead.

The numbers

How much is actually in leaf

This matters because thresholds are being written into law. The best available measurements:

  1. 341 products people were actually using FDA's own assessment reports 7-OH content ranging from below the limit of quantitation (under 0.005%) to a maximum of 0.21%, with a mean of 0.01%. The products were primarily whole-leaf. (FDA CDER assessment, 2025, citing Sharma et al., Drug Testing and Analysis.)
  2. Fresh leaf, measured at source Fresh leaves collected across Peninsular Malaysia measured 0.005% to 0.015% of dried leaf weight. (FDA CDER assessment, 2025.)
  3. It moves after harvest, and downward with heat In a controlled two-cultivar experiment, leaf 7-OH was below the limit of quantification in most conditions and varied by season and cultivar. Contrary to a common claim, heat reduced it — 21–39% higher at 25°C than at 60°C. (Zhang et al., Frontiers in Plant Science, 2025.)
  4. And it degrades Across pH 2–10 and 4–80°C, 7-OH was the most unstable Mitragyna alkaloid tested, with significant loss within eight hours at 40°C and above. (Basiliere et al., Journal of Analytical Toxicology, 2020.)
Why this is an administrability problem

A percentage threshold assumes a stable quantity. 7-OH is not stable — it varies with cultivar, season, withering time and storage, and it degrades in both directions. A single assay cannot reliably establish what a product contained last month or will contain next month. That is an argument any regulator has to answer, and it does not depend on anyone's opinion about safety.

What it does

A potent mu-opioid agonist

7-OH is a potent agonist at the mu-opioid receptor. Not "not really an opioid," not a technicality. Anyone arguing otherwise is going to lose in front of a pharmacologist, and deserves to.

Naloxone works on it. In rats, naloxone reversed 7-OH-induced respiratory depression — the published abstract's own word is "fully." Standard opioid overdose response applies. Nothing on this site should ever be read as a reason to hesitate about naloxone. (Zuarth Gonzalez et al., JPET, 2025.)

There is now controlled human data on the leaf. A randomised, double-blind, placebo-controlled dose-escalation trial in 116 volunteers — single doses up to 53.2 mg mitragynine, then fifteen consecutive daily doses — reported no serious adverse events or deaths, and the authors concluded the leaf powder was safe and well tolerated at the doses tested. Read that sentence exactly: the volunteers were kratom-naive and screened, fifteen days is not chronic use, heavy users take several times that daily, and raised liver enzymes were among the more common multiple-dose findings. (Huestis et al., Therapeutic Drug Monitoring, 2026.)

On breathing, the picture is specific rather than reassuring. Mitragynine's respiratory depression in mice plateaued — doses from 10 to 90 mg/kg produced no more depression than 10 mg/kg alone. Plateaued is not absent: the same study recorded significant and prolonged depression at that dose. (Hill et al., British Journal of Pharmacology, 2022.)

Potency figures move a great deal depending on the assay used, so treat any single multiple with suspicion — including ones quoted by people on our side. The same compounds measured 105–108% of a reference opioid's maximal effect in one assay and 60–70% in a less amplified one, and the authors noted the first type substantially overestimates efficacy. (Chakraborty et al., J Med Chem, 2021.)

The number in the bills

Where does 0.050% come from?

A single figure — 0.050% by dry weight — is doing most of the work in the federal action and is being copied into state bills. It is worth asking a plain question about it, and it is a question you can ask without any pharmacology at all.

When the Department of Health and Human Services opened its public docket on the threshold, it asked the public whether any additional data exist that further support this or an alternative threshold level, and what concentration of 7-OH in a product actually constitutes a concern.

Ask it carefully, and it holds

A request for information is a short notice and would not normally carry citations, so its silence is not proof that no derivation exists anywhere in the record. The fair version of the question is the strong one: where is the published toxicological derivation of 0.050%? If it exists, an agency asking the public to supply supporting data should be able to point at it. If it does not, a number with no shown work is being written into law in a dozen states.

That question is also open to you. The docket is a public comment process, and "I could not find the basis for this number and I would like to see it" is a complete, legitimate comment from a member of the public. How to find where to say it.

Where we stand on this

Origin is not a safety finding

Haven Access supports access to kratom and all of its alkaloids — natural, extracted, concentrated, isolated, semi-synthetic or synthesised. Not because origin is irrelevant to chemistry, but because it is irrelevant to safety. A contaminated product is dangerous however it was made. A clean, tested, honestly labeled product sold to an adult is not made dangerous by having been synthesised.

That is why our model act defines a protected alkaloid as any natural kratom alkaloid and 7-OH in any form, and why Section 5(c) bars any agency from capping or conditioning one "solely because it is natural, concentrated, isolated, synthetic, semi-synthetic, converted, refined, imported, or otherwise produced."

This is not "anything goes"

Unfettered access is not unregulated access. Everything we ask for still applies to a concentrate: independent lab testing on every batch, alkaloid content disclosed per serving, a dependence warning, child-resistant packaging, 21-and-up. A genuinely new alkaloid still goes through premarket review. What we reject is prohibition standing in for any of that.

Arguments we will not make

Even though they would help

An advocacy page that only carries favourable evidence is worth nothing in a hearing, because the other side has read the same literature. These are claims we hear from people who agree with us, and will not repeat.

"It's G-protein biased, so it's safer"

This is dead. The founding result failed replication, the measurements were confounded by assay amplification, and in 2021 the research group that proposed it retired the framing in print. It is still repeated constantly. Say it in front of anyone who knows the field and the rest of your testimony stops being heard. (Chakraborty et al., J Med Chem, 2021.)

"Kratom doesn't cause dependence"

It does. The most comprehensive pro-kratom abuse-potential review says in its own words that there does appear to be evidence of physical dependence — weaker and shorter-lived than morphine's, but real. The honest claim is always comparative, never absolute. It is also why we ask for a dependence warning on every label. (Henningfield et al., Frontiers in Pharmacology, 2021.)

"Restricting it will drive people to fentanyl"

Stated as a certainty, this is not supportable. Stated as a risk, it is reasonable and worth raising: restriction pushes a market toward channels nobody inspects. Say "risks", not "will".

The number you will be asked about

Deaths, in the context they were recorded in

The CDC examined 27,338 overdose deaths across 27 states. Kratom was detected in 152 of them. In only seven was kratom the sole substance found on postmortem toxicology — and the CDC itself cautioned that other substances could not be ruled out even in those.

Among the 152, fentanyl or its analogues were listed as a cause of death in 65.1%, heroin in 32.9%, benzodiazepines in 22.4%. The CDC's own conclusion was that kratom was most often detected alongside multiple other substances. (Olsen et al., MMWR, 2019.)

That is the honest shape of the evidence: detection is not causation, and polysubstance context is the norm. It is a stronger argument than any headline number, because it is the government's own analysis.

Read them yourself

Sources

If you are testifying, cite these directly. A committee that has heard "dangerous synthetic" all morning reacts differently to a citation, and everything here is checkable.

Read the funding line, on both sides

Every paper prints who paid for it and what the authors stand to gain. It is usually two lines above the references and almost nobody reads it. Get in the habit, because the other side will.

Apply it evenly or it is not a method, it is a weapon. The 2019 paper we cite above was funded in part by an industry trade association, and five of its authors are named on patent applications for mitragynine analogs that could earn royalties. That does not make its chemistry wrong — it was also NIDA-funded and it is open access, so you can check every figure. It does mean anyone citing it in testimony should say so first rather than be corrected.

The same test applied the other way is why the biased-agonism claim above cannot be waved off as an opposition finding: it was withdrawn by the same research group that proposed it. A funding motive does not explain scientists retracting their own work.

This page will go out of date

The biased-agonism claim was good science in 2019 and wrong by 2021. Anything here could go the same way. If you find research that cuts against something on this page, send it to us — a position that only survives on selected evidence is not worth holding.

Where we stand Back to Learn

None of this is medical advice and we are not a medical organisation. If you use kratom to manage pain or to stay off opioids, that is worth discussing with a clinician who will hear it without flinching.