Kratom Encyclopedia

Kratom research library

24 studies and government sources. Each finding below is quoted from the paper's abstract or open full text, checked Oct 7, 2026.

21+ only. Kratom is not approved by the FDA for any medical use, and nothing here is medical advice.

Avula 2026

Avula B, Ali SK, Tatapudi KK, Pandey P, Cheepilla L, Husain I, Khan SI, Katragunta K, Ali Z, Khan IA, Chittiboyina AG. Quantitative analysis of 7-hydroxymitragynine in commercial kratom products and its stability under chemical and physiological conditions. Phytochemistry. 2026;247:114871.

Design: Product testing + stability experiments (simulated gastric conditions)

  • Over 98% of 7-OH-labelled products showed a semisynthetic origin.
  • Measured 7-OH often did not match label claims.
  • 7-OH breaks down to 3-dehydromitragynine, a potentially toxic byproduct, under simulated stomach conditions.

Limitations: Number of products not in the abstract; abstract only (paywalled). The abstract also reports labelled per-serving amounts — deliberately not reproduced (no dosing content).

Brown 2026

Brown PN, Chan M, Zhang X, Brendler T. Elevated 7-Hydroxymitragynine Levels Found in Products Misbranded as Kratom. J AOAC Int. 2026;109(1):124-130.

Design: Product testing (HPLC-DAD, AOAC Official Method 2017.14) vs authentic leaf

  • Products labelled 'kratom extract' had low mitragynine (2.0–6.0 mg/g) but 7-OH at 22–75 mg/g, 5–28% above label claims.
  • Their chemical profiles did not match kratom leaf; such 7-OH levels are achievable only synthetically.
  • Five brands were tested.

Limitations: Five brands, small number of packages (some same lot); US retail purchases at one time; HPLC-DAD with leaf comparison, so 'synthetic' is inferred from profile.

CDC MMWR 2026

Towers EB, Thomas YT, Holstege CP, Farah R. Increases in Kratom-Related Reports to Poison Centers — National Poison Data System, United States, 2015–2025. MMWR Morb Mortal Wkly Rep. 2026;75(11):139-145. Published 2026-03-26.

Design: government report (surveillance analysis of National Poison Data System)

  • Poison-centre kratom reports rose about 1,200%, from 258 in 2015 to 3,434 in 2025; 14,449 reports over 11 years.
  • Of 233 kratom-associated deaths, 184 (79%) involved multiple substances; opioids were reported in 62% of fatalities.
  • Multiple-substance reports had higher hospitalization rates (44–56% vs 24–29% annually).
  • The 2025 surge coincides with high-potency semisynthetic products including 7-OH.
  • The data cannot distinguish traditional leaf products from semisynthetic or concentrated products.

Limitations: Voluntary poison-centre reports (undercount of mild events, possible repeat callers); no product-type data; cannot attribute outcomes to kratom when other substances are involved.

Gour 2026

Gour A, Kanumuri SRR, Mukhopadhyay S, Pullman MK, León F, Cutler SJ, McCurdy CR, Sharma A. Mislabeling and Status of Semisynthetic Kratom-Derived Products in the US Market. Drug Test Anal. 2026;18(10):1286-1295.

Design: Product testing (UPLC-MS/MS)

  • Tablets, films and shots varied widely and often did not match their labels.
  • Many contained unlisted active compounds such as 7-OH and 3-dehydromitragynine.

Limitations: Product count and concentrations not in the abstract; abstract only (paywalled).

Hill 2026

Hill K, Henderson A, Sharma A, Kanumuri SRR, Mukhopadhyay S, Veltri C, Smith KE, McCurdy CR, Grundmann O. Diversification of Kratom in US Markets: Results from an Online Survey and Chemical Assay of Products. Subst Use Misuse. 2026;61(2):237-246.

Design: Anonymous online survey + chemical assay (UPLC-MS/MS) of products

  • Survey of 421 users of 61 products recruited through six vendors.
  • Whole-leaf powders were the most popular form and were reported to give more pain relief, energy and better sleep than other forms (self-report).
  • Constipation was the most common reported adverse effect.
  • Alkaloid content differed by product form: higher in edibles and whole-leaf powders than in teas and concentrated liquid extracts.

Limitations: Recruitment through six vendors (vendor customers, self-selected); effects are self-reported; results are by product form, not strain. Abstract only.

Krongrawa 2026

Krongrawa W, Ponphaiboon J, Koedruen J, Samran C, Limmatvapirat S, Limmatvapirat C. Effects of Botanical Variation, Plant Part, and Extraction Technique on Mitragynine and 7-Hydroxymitragynine in Kratom (Mitragyna speciosa) Extracts Quantified by a Validated HPLC-DAD Method. Molecules. 2026;31(13):2241.

Design: Analytical method validation (HPLC-DAD) + extraction comparison on Thai plant material

  • The abstract reports green-veined leaves contained more mitragynine than red-veined leaves — the one retrieved study with a vein-colour difference.
  • The difference is small: in northern samples, green-veined UAE extract had 58.07 µg/mg vs 57.20–57.57 µg/mg for red-veined; region mattered more (southern samples 46.14–47.39 µg/mg).
  • Southern samples had lower mitragynine but relatively more 7-OH; 7-OH was found only in leaves.
  • The authors themselves describe the colour effect as a tendency to slightly higher mitragynine.

Limitations: Small set of Thai trees (one red, one green, one Hang Kang source per region); values are µg per mg of ethanol extract, not leaf; botanical vein colour, not US processing colour; the colour difference is ~1% relative and smaller than the regional difference.

LAPPA 2026

Legislative Analysis and Public Policy Association. Kratom: Summary of State Laws. January 2026 (research current as of January 2026; PDF dated 2026-02-05). ONDCP-funded.

Design: legal summary (ONDCP-funded 50-state law survey, 122 pp.)

  • As of January 2026, 30 states and DC regulate kratom; six states (AL, AR, IN, LA, VT, WI) control mitragynine and 7-OH, banning all kratom products.
  • Florida, Ohio and DC schedule only 7-OH.
  • 14 states limit 7-OH concentration and/or ban synthetic 7-OH without scheduling alkaloids.
  • 19 states have labelling rules; 22 have age limits (18+ in seven states, 21+ in 15).
  • Nineteen states impose product-labelling requirements.
  • Seven states license processors and/or retailers.
  • Twenty states do not regulate kratom at all.
  • 35 states introduced kratom legislation during 2025 and as of January 2026.

Limitations: Snapshot as of January 2026; does not cover 2026 state changes (e.g., KS, CT, TN) or the 2026 federal 7-OH temporary scheduling; local ordinances not tracked. Not a statute — cite the statute on state pages.

NIDA Kratom

National Institute on Drug Abuse. Kratom. Research topic page. nida.nih.gov (retrieved 2026-10-07).

Design: government page

  • NIDA describes kratom as producing opioid- and stimulant-like effects.
  • Rare but serious effects have been reported; deaths are very few and nearly all involved other drugs or contaminants.
  • Very few deaths are linked to kratom, nearly all involving other drugs or contaminants.
  • About 0.6% of people 12+ (about 1.7 million) reported past-year use in 2021 (NSDUH).
  • Kratom is not on the federal controlled-substances schedule; DEA lists it as a drug of concern (as stated by NIDA).

Limitations: The page's federal-status statement predates the 2026 temporary scheduling of 7-OH above a threshold; check against the Federal Register. No 'reviewed' date was visible in the fetched HTML (schema datePublished 2022-05-26); the research note's 2026-03-11 review date could not be confirmed. No strain information.

Ransden 2026

Ransden KE, Ramachandria P, Laforest LC, Kanumuri SRR, Sharma A, McCurdy CR, Nadakuduti SS. Comparative analysis of monoterpene indole alkaloid composition and genotypic variation in Thai Mitragyna speciosa. Front Plant Sci. 2026;17:1821609.

Design: Plant genotyping (DNA barcoding) + targeted alkaloid profiling (UPLC-MS)

  • Mitragynine reached up to 1.19% of leaf dry mass in mature leaves; juvenile leaves were dominated by speciociliatine (up to 1.14%).
  • Despite visibly different vein colours, mature-leaf alkaloid profiles were largely the same across accessions.
  • No correlation between vein colour and alkaloid profile; vein colour varied on a single tree with leaf age.
  • Leaf developmental stage mattered more than accession or genotype.

Limitations: Eight accessions grown from Thai seed in one greenhouse; fresh, flash-frozen leaves rather than dried commercial powder; 'vein colour' is botanical, not the processing colour used in US marketing.

FDA and Kratom

U.S. Food and Drug Administration. FDA and Kratom. Public health focus page. Content current as of 12/02/2025.

Design: government page

  • Kratom is not lawfully marketed in the US as a drug, dietary supplement or food additive.
  • FDA warns of serious adverse events including liver toxicity, seizures and substance use disorder.
  • Natural 7-OH is a minor constituent, under 2% of total alkaloids in natural leaves, but far more potent at the mu-opioid receptor than mitragynine.
  • In rare deaths associated with kratom, it was usually combined with other drugs and its contribution is unclear.

Limitations: Regulatory position page; the page also contains a self-reported per-use amount, deliberately not reproduced (no dosing content).

Sharma 2025

Sharma A, Smith KE, Kuntz MA, Berthold EC, Elashkar OI, Guadagnoli N, Kanumuri SRR, Mukhopadhyay S, Panlilio LV, Epstein DH, McCurdy CR. Chemical Analysis and Alkaloid Intake for Kratom Products Available in the United States. Drug Test Anal. 2025;17(10):1974-1984.

Design: Product chemical analysis linked to an ecological momentary assessment (EMA) study of US consumers

  • The 341 products consumers actually used were mostly whole-leaf and similar to each other in alkaloid composition, matching the expected leaf fingerprint.
  • No adulteration with illicit or prescription drugs was found.
  • Alkaloid intake was calculated from how much people reported using, i.e. it is intake-based, not strain-based. (Intake figures deliberately not reproduced: no dosing content.)

Limitations: Convenience sample of consumers in an EMA study; products are those participants happened to use; per-sample concentration ranges are not in the abstract. Abstract only. Site rule: do not reprint the per-use or per-day mg figures.

Zhang 2025

Zhang M, Lyndon A, Kanumuri SRR, Sharma A, Pearson BJ, McCurdy CR, Chen J. Alkaloid biosynthesis in medicinal crop kratom (Mitragyna speciosa) varies with postharvest, genetic, and seasonal factors. Front Plant Sci. 2025;16:1653916.

Design: Controlled postharvest experiment (two studies, two seasons)

  • Withering raised mitragynine by 14–65% in 'Hawaii' and 3–8% in 'MR-Malaysian' leaf alkaloid extracts.
  • 7-OH averaged 0.02–0.04% in leaf alkaloid extracts and was detected only in some seasons.
  • Processing changes powder colour: high drying temperatures gave reddish-brown powder, low temperatures green — the same leaves can end up different colours.
  • Alkaloid composition depends on genotype, season and postharvest handling.

Limitations: Two US-grown cultivars under experimental conditions; percentages are in leaf alkaloid extracts, not whole leaf; does not test commercial 'strains'.

Hill 2023

Hill K, Gibson S, Grundmann O, Smith KE, Ballard J, Stanciu CN. Evaluating health information provided to kratom consumers by good manufacturing practice-qualified vendors. Subst Abuse Treat Prev Policy. 2023;18(1):21.

Design: Website content evaluation (DISCERN instrument)

  • The 42 AKA GMP-qualified vendor sites averaged 32.72 out of 75 on DISCERN.
  • Information on risks and benefits was particularly insufficient.
  • 36 of 42 sites gave little reference to sources for their claims.

Limitations: Snapshot of 42 vendor sites in January 2023; DISCERN was designed for treatment information and is subjective rating.

Huisman 2023

Huisman G, Menke M, Grundmann O, Schreiber R, Mason N. Examining the Psychoactive Differences between Kratom Strains. Int J Environ Res Public Health. 2023;20(14):6425.

Design: Anonymous online survey (cross-sectional) + independent-lab COA comparison

  • Vendor claims that strains have distinct effects are unsubstantiated; 644 users were surveyed about red, green and white products.
  • Six strain-labelled products (three batches each) did not differ in mitragynine, other major alkaloids or total alkaloids.
  • Mean mitragynine per product (Table 6): White Maeng Da 1.54%, Red Maeng Da 1.52%, Green Bali 1.44%, White Thai 1.41%, Green Maeng Da 1.56%, Red Bali 1.4% (F = 1.21, p = 0.362).
  • Mean total alkaloid content per product (Table 6, same column order): 2.44%, 2.37%, 2.28%, 2.25%, 2.42%, 2.2% (F = 0.92, p = 0.5).
  • Users nonetheless reported effects that matched marketing: for 'better able to concentrate' (0–100 scale) means were green 60.98, red 49.79, white 69.42.
  • For 'feeling more energetic' means were green 64.46, red 52.93, white 66.5 (red lower than both).
  • For 'feeling more stimulated' means were green 52.94, red 48.79, white 62.61 (white highest).
  • For 'feeling more constipated than usual' means were green 26.45, red 39.39, white 41.74; for 'able to stay up all night' green 26.45, red 18.43, white 41.14.
  • 'Feeling calmer' did not differ significantly by colour (green 64.55, red 65.24, white 58.71; p = 0.1115), despite red being marketed as relaxing.
  • The authors conclude reported effect differences may reflect marketing narratives, since alkaloid content did not differ.

Limitations: Single vendor: COAs are six Super Speciosa products (three batches each) and most respondents were that vendor's customers, which the authors say limits generalisability. Effects are retrospective self-report on 0–100 sliders, not blinded; sample overwhelmingly Caucasian American. Only four alkaloids plus total measured (no 7-OH in Table 6). Red Bali is printed as 1.4% (not 1.40%) in Table 6. The survey/COA vendor is a partner brand of this site — disclose.

Sengnon 2023

Sengnon N, Vonghirundecha P, Chaichan W, Juengwatanatrakul T, Onthong J, Kitprasong P, Sriwiriyajan S, Chittrakarn S, Limsuwanchote S, Wungsintaweekul J. Seasonal and Geographic Variation in Alkaloid Content of Kratom (Mitragyna speciosa (Korth.) Havil.) from Thailand. Plants (Basel). 2023;12(4):949.

Design: Field sampling study (HPLC), two collections across Thai regions and seasons

  • In the first collection, leaf mitragynine peaked at 4.94% in June and was lowest at 0.74% in October.
  • Across 611 samples from three seasonal collections, mitragynine ranged 0.35–3.46%, 0.31–2.54% and 0.48–2.81%.
  • Geography affected mitragynine but not vein colour.
  • Red- and green-veined leaves produced similar alkaloid levels, with no significant differences.

Limitations: Fresh Thai leaves, not US retail products; only three alkaloids (no 7-OH); vein colour is the tree's leaf-vein colour, not the processed 'strain' colour sold in the US.

Manwill 2022

Manwill PK, Flores-Bocanegra L, Khin M, Raja HA, Cech NB, Oberlies NH, Todd DA. Kratom (Mitragyna speciosa) Validation: Quantitative Analysis of Indole and Oxindole Alkaloids Reveals Chemotypes of Plants and Products. Planta Med. 2022;88(9-10):838-857.

Design: Analytical method validation (UHPLC-HRMS) applied to US-grown plants and commercial products

  • Commercial products shared a similar alkaloid profile with high mitragynine, from 13.9 to 270 mg/g; other alkaloids varied product to product.
  • A US-grown plant called 'Rifat' was high in speciogynine, suggesting several M. speciosa chemotypes exist.

Limitations: The 270 mg/g upper value comes from a concentrated product, not leaf powder; product count, product types and strain labels are not in the abstract. Chemotype finding rests on few US-grown plants. Full text not openly licensed (author manuscript in PMC).

Chear 2021

Chear NJ, León F, Sharma A, Kanumuri SRR, Zwolinski G, Abboud KA, Singh D, Restrepo LF, Patel A, Hiranita T, Ramanathan S, Hampson AJ, McMahon LR, McCurdy CR. Exploring the Chemistry of Alkaloids from Malaysian Mitragyna speciosa (Kratom) and the Role of Oxindoles on Human Opioid Receptors. J Nat Prod. 2021;84(4):1034-1043.

Design: Phytochemical isolation + UPLC-MS/MS quantification + receptor binding and rat hot-plate assay

  • Ten indole and oxindole alkaloids were isolated from fresh Malaysian leaves and quantified across collection sites.
  • The minor oxindole alkaloid corynoxine bound the mu-opioid receptor strongly (Ki 16.4 nM), so minor alkaloids may matter.

Limitations: Site-level concentrations are not in the abstract; animal and receptor data do not translate directly to human effects. Full text not openly licensed (author manuscript in PMC).

Prozialeck 2020

Prozialeck WC, Edwards JR, Lamar PC, Plotkin BJ, Sigar IM, Grundmann O, Veltri CA. Evaluation of the Mitragynine Content, Levels of Toxic Metals and the Presence of Microbes in Kratom Products Purchased in the Western Suburbs of Chicago. Int J Environ Res Public Health. 2020;17(15):5512.

Design: Product testing (cross-sectional), 8 retail products

  • All eight products contained mitragynine, at 3.9 to 62.1 mg/g, confirming they were kratom-derived.
  • Leaf products held 3.35–11.33 mg/g mitragynine; the one concentrated extract held 59.76 mg/g. None had detectable 7-OH, opioids or benzodiazepines.
  • Seven of eight products had measurable nickel, lead and chromium; all but two had microbes; none had Salmonella.

Limitations: Only 8 products from one metro area at one time; single purchase per product; strain names are vendor labels and the study does not compare strains.

Todd 2020

Todd DA, Kellogg JJ, Wallace ED, Khin M, Flores-Bocanegra L, Tanna RS, McIntosh S, Raja HA, Graf TN, Hemby SE, Paine MF, Oberlies NH, Cech NB. Chemical composition and biological effects of kratom (Mitragyna speciosa): In vitro studies with implications for efficacy and drug interactions. Sci Rep. 2020;10(1):19158.

Design: Untargeted LC-MS metabolomics of commercial products + DNA barcoding + in vitro receptor/CYP assays

  • Profiling 53 commercial products found two chemotypes that differ in speciofoline; both were confirmed as M. speciosa.
  • Across the commercial samples, mitragynine varied about fourfold, speciofoline more than 90-fold.
  • In the quantified products, mitragynine was 11.45 mg/g (1.145%) in one and 8.13 mg/g in another; 7-OH was 0.056 mg/g in the first (Table 1 gives 0.0349 mg/g for the second).
  • The authors cite prior literature putting mitragynine at 1–6% and 7-OH at 0.01–0.04% of leaf content in commercial products.
  • Mitragynine, 7-OH and speciofoline inhibited some cytochrome P450 enzymes, a possible drug-interaction risk.

Limitations: Absolute quantification only for three commercial products (K50 11.37, K51 11.45, K52 8.13 mg/g mitragynine; 7-OH 0.053, 0.056, 0.0349 mg/g); the 53-product comparison is relative (peak areas). The 1–6% / 0.01–0.04% figures are cited from earlier work, not measured here. In vitro findings only.

Fowble 2019

Fowble KL, Musah RA. A validated method for the quantification of mitragynine in sixteen commercially available Kratom (Mitragyna speciosa) products. Forensic Sci Int. 2019;299:195-202.

Design: Analytical method validation (DART-HRMS) applied to commercial products

  • Mitragynine in 16 commercial kratom plant products ranged from 2.76 to 20.05 mg per gram of dried plant material (about 0.28% to 2.0%).

Limitations: 16 products bought online at one time point; mitragynine only (no 7-OH quantified); products not identified by strain in the abstract. Abstract only (paywalled).

Sharma 2019

Sharma A, Kamble SH, León F, Chear NJ, King TI, Berthold EC, Ramanathan S, McCurdy CR, Avery BA. Simultaneous quantification of ten key Kratom alkaloids in Mitragyna speciosa leaf extracts and commercial products by ultra-performance liquid chromatography-tandem mass spectrometry. Drug Test Anal. 2019;11(8):1162-1171.

Design: Analytical method validation (UPLC-MS/MS) applied to leaf fractions, extracts, teas and commercial products

  • Across the extracts and products analysed, mitragynine ranged from 0.7% to 38.7% by weight; the other major alkaloids were paynantheine, speciociliatine and speciogynine.
  • Minor alkaloids, including 7-hydroxymitragynine, were measured at 0.01% to 2.8% by weight (a combined range for five minor alkaloids, not 7-OH alone).

Limitations: Ranges pool very different materials (alkaloid-rich fractions and extracts as well as teas and commercial products), so the upper ends are not typical of leaf powder. The 0.01–2.8% figure is a combined range for five minor alkaloids. Product count and per-product values are not in the abstract; full text not openly licensed (author manuscript in PMC).

AOAC 2017.14

Mudge EM, Brown PN. Determination of Alkaloids in Mitragyna speciosa (Kratom) Raw Materials and Dietary Supplements by HPLC-UV: Single-Laboratory Validation, First Action 2017.14. J AOAC Int. 2018;101(4):964-965.

Design: Official method summary (single-laboratory validation, AOAC First Action)

  • AOAC's expert panel adopted the method for mitragynine and 7-OH as First Action Official Method 2017.14.
  • Repeatability RSD was 0.51–0.95% and recoveries 93.6–98.9% across matrices.

Limitations: Single-laboratory validation (First Action, not Final Action); covers only two alkaloids. Whether a given COA lab uses this method must be checked per COA. Abstract only.

Lydecker 2016

Lydecker AG, Sharma A, McCurdy CR, Avery BA, Babu KM, Boyer EW. Suspected Adulteration of Commercial Kratom Products with 7-Hydroxymitragynine. J Med Toxicol. 2016;12(4):341-349.

Design: Product testing (LC-MS/MS)

  • Several commercial products had 7-OH concentrations well above those in raw leaf, suggesting adulteration.

Limitations: Small, unspecified number of products; concentrations not given in the abstract; 'adulteration' is inferred from 7-OH levels. Full text not openly licensed (author manuscript in PMC).