Kratom

What the Research Shows

4 records from the 2026-08-18 harvest, each checked against PubMed and Europe PMC on that date. How a study was designed, how many people were in it, and who paid for it are printed above what it found, because those three facts decide how much the finding is worth.

1. Study 1 · 2018

   • Systematic review of observational studies
   • Reputable journal
   • Funding not established
   moderate57/100

   Reasonable evidence with real limitations.

   A systematic review of all studies on kratom and mental health from 1960 to 2017 found only observational and self-report evidence — no controlled trials. Users commonly report mood enhancement, anxiety relief, and use as an opioid substitute, but the same literature documents dependence and withdrawal that some users find highly uncomfortable; no efficacy for any psychiatric condition has been demonstrated in a clinical trial.

   Swogger MT, Walsh Z. (2018). Kratom use and mental health: A systematic review. Drug and Alcohol Dependence. PMID 29248691.

   How this record was checked

   PubMed record 29248691 fetched via NCBI efetch 2026-08-18; title, authors, journal, year, and DOI confirmed against the record. Europe PMC core record checked 2026-08-18: no funding/grant statement available, so funding recorded UNKNOWN.

2. Study 2 · 2017

   • Cross-sectional study
   • 8,049 participants
   • Reputable journal
   • Industry funded
   contested32/100

   Weak or heavily disputed. Treat as a question, not an answer.

   Read this first: Funded by the American Kratom Association, a pro-kratom advocacy organization, and respondents were recruited through its channels — a design that samples satisfied current users and is structurally biased toward favorable results.

   In an anonymous online survey of 8,049 US kratom users recruited through the American Kratom Association, most were middle-aged and used kratom to self-treat pain (68%) or emotional/mental conditions (66%); adverse effects (mainly nausea and constipation) were dose-dependent, appearing chiefly at doses of 5 g or more taken 22 or more times per week. As a self-selected survey of current users recruited via an advocacy group, it cannot measure efficacy, dependence rates, or harms in people who stopped using.

   Grundmann O. (2017). Patterns of Kratom use and health impact in the US-Results from an online survey. Drug and Alcohol Dependence. PMID 28521200.

   How this record was checked

   PubMed record 28521200 fetched via NCBI efetch 2026-08-18; title, author, journal, year, DOI, and N=8049 completed responses confirmed from the abstract. Europe PMC core record fetched 2026-08-18 lists grant agency "American Kratom Association", hence funding INDUSTRY and independent false.

3. Study 3 · 2020

   • Randomized trial
   • 26 participants
   • Indexed journal
   • Independently funded
   moderate68/100

   Reasonable evidence with real limitations.

   The first randomized, placebo-controlled, double-blind human study of kratom — 26 Malaysian men with about 6 years of daily use — found cold-pressor pain tolerance roughly doubled one hour after a kratom decoction (11.2 to 24.9 seconds, p=0.02) with no change after placebo, and no withdrawal signs over 10-20 hours of abstinence. This tiny single-dose study in habituated users is essentially the entire controlled-trial evidence base for kratom; it says nothing about mental health outcomes, safety, or new users.

   Vicknasingam B, Chooi WT, Rahim AA, et al. (2020). Kratom and Pain Tolerance: A Randomized, Placebo-Controlled, Double-Blind Study. Yale Journal of Biology and Medicine. PMID 32607084.

   How this record was checked

   PubMed record 32607084 fetched via NCBI efetch 2026-08-18; title, authors, journal, year, and N=26 confirmed from the abstract. Europe PMC core record fetched 2026-08-18 confirms no DOI assigned (PMCID PMC7309661) and lists NIH NCATS grant UL1 TR001863, hence funding INDEPENDENT.

4. Study 4 · 2019

   • Systematic review of observational studies
   • Reputable journal
   • Funding not established
   moderate57/100

   Reasonable evidence with real limitations.

   A systematic review of the kratom-withdrawal literature plus the authors' own cases concluded that chronic kratom use produces dependence, tolerance, and an opioid-like withdrawal syndrome on cessation — including in people with no opioid history — and that clinicians increasingly see such presentations. The evidence base is case reports and series, not controlled studies, so the frequency of withdrawal among users cannot be estimated from it.

   Stanciu CN, Gnanasegaram SA, Ahmed S, Penders T. (2019). Kratom Withdrawal: A Systematic Review with Case Series. Journal of Psychoactive Drugs. PMID 30614408.

   How this record was checked

   PubMed record 30614408 fetched via NCBI efetch 2026-08-18; title, authors, journal, year, and DOI confirmed against the record. Europe PMC core record checked 2026-08-18: no funding statement available, so funding recorded UNKNOWN.

The Risks

Nobody checks this purchase the way a prescription is checked. No prescriber reviews it against the rest of what you take, no pharmacist screens the interaction, and no regulator confirms the dose in the capsule before it is sold. That is why this section sits here at full length rather than as a footnote.

What the paragraph below covers:

• Slowed breathing
• Liver injury
• Dependence and withdrawal
• Drug interactions
• Fertility and pregnancy
• What is actually in the product
• Sedation

What Is Not Known

The boundaries of the section above, in the harvest’s own words. What it excluded, why, and where it looked and found nothing. An absence of evidence is not evidence of absence, and it is not evidence of benefit either.

What Was Left Out, and Why

Quoted from the harvest, where these notes sat above the study list rather than after it. Where a note says “below” it means the studies in the section above.

• Individual kratom hepatotoxicity and death case reports (numerous PMIDs) excluded in favor of the systematic reviews below, which subsume them.
• No meta-analysis of RCTs exists for any kratom indication; the single verified human RCT (Vicknasingam 2020, n=26, pain tolerance in habitual users) is included and is the entirety of controlled human evidence found. That absence is the story.

The Retraction Check

PubMed efetch records for all four PMIDs inspected 2026-08-18 for "Retraction in" flags; none present.

Questions for a Prescriber or Pharmacist

This page does not tell anyone to take Kratom or to avoid it. It is not able to: it does not know what else you take, what you have tried, or what you are treating. These are the questions each study above raises, written to be asked out loud.

• I've been using kratom for my mood or anxiety — given that there are no controlled trials showing it works, what evidence-based treatment could replace it, and how would we manage withdrawal if I stop?
• Survey data show most people use kratom to self-treat pain or mood problems — if that's why I'm using it, what proven treatment for the underlying condition should we try instead?
• The only placebo-controlled kratom study involved 26 experienced users and a single dose for pain tolerance — does anything about my situation justify relying on evidence that thin?
• If I've been taking kratom daily, what is the safest plan for tapering off, and should my withdrawal be managed the way opioid withdrawal is?

And the one to ask at the counter, whatever the answers above turn out to be: given everything I am already taking, what would you want to know about Kratom before I put it in the same body?

The Other Substances

• 5-HTP
• Ashwagandha
• Cannabidiol (CBD)
• Cannabis and THC
• Creatine
• L-Theanine
• Magnesium
• Melatonin
• Methylene Blue
• Microdosing
• N-Acetylcysteine (NAC)
• Omega-3
• Phenibut
• SAMe
• St John’s Wort
• Valerian

Do any supplements actually work? asks the question across all of them. The full library has the medication records, the funding investigations, and the glossary.