What does the research show about kratom?

Kratom

Grey marketNot approved for human use in the US, and sold anyway.

In a small placebo-controlled study of daily users, kratom raised cold-pain tolerance from 11 to 25 seconds. No trial of opioid withdrawal, mood or anxiety was sourced. FDA states kratom cannot be lawfully sold as a supplement. It was found in 152 US overdose deaths in 18 months, and studies report dependence, liver injury, Salmonella and heavy metals.

Add to Bio HackChecked 2026-11-09

Status: Not FDA-approved for any use. FDA states kratom is not lawfully marketed in the US as a drug, dietary supplement or food additive. In 2025 and 2026, FDA and DEA moved to place concentrated 7-OH and mitragynine pseudoindoxyl (MGPI) products in Schedule I.
Also called: Mitragyna speciosa, mitragynine, 7-hydroxymitragynine, 7-OH, ketum, biak, thang, kakuam, kratom extract, kratom shots
Taken for: pain, opioid withdrawal, energy, focus, mood, anxiety

Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on

Shown to help3

LimitedOne small trial found cold pain tolerance rose 1 hour after kratom in men who used it daily. No trial in chronic pain was found.
LimitedOne small study found a low dose of mitragynine raised self-rated alertness and attention, while the highest dose raised self-rated amnesia.
LimitedLinked to small drops in momentary anxiety and, less consistently, sadness in the hours after use among regular users tracked by phone. No randomized trial was located.

Reported risks12

LimitedFDA states kratom is not appropriate for use as a dietary supplement, and lists reported liver toxicity, seizures and substance use disorder.
LimitedFDA proposed scheduling concentrated 7-OH products in 2025, not natural kratom leaf. DEA placed some related compounds in Schedule I in 2026.
LimitedSmall trials found dizziness, nausea and headache rising with dose, and no serious adverse events. Higher doses raised drug liking ratings.
LimitedLimited evidence: kratom was detected in 0.56% of US overdose deaths studied, mostly with other drugs such as fentanyl, and was the only substance in 7.
LimitedCase reports: US poison centers logged 1,807 kratom exposures from 2011 to 2017, with 11 deaths. Agitation and fast heart rate were most common.
LimitedLimited evidence: in surveys of regular users, many met criteria for dependence or kratom use disorder, with withdrawal symptoms on stopping.
LimitedCase reports: newborns developed withdrawal after their mothers used kratom in pregnancy. FDA states it is aware of such cases.
LimitedCase reports: liver injury with jaundice after kratom, mostly improving after stopping, with four cases progressing to liver transplant.
LimitedCase reports: 24 reports of lung outcomes after kratom exposure, including bleeding in the lungs and depressed breathing. All clinical patients survived.
LimitedCase reports: 20 patients had seizures after reported kratom use. Reviewers found the evidence insufficient to show kratom causes them.
LimitedCase reports: a 2017 to 2018 Salmonella outbreak linked to kratom sickened 199 people in 41 states, and 38% of those with data were hospitalized.
LimitedFDA states its tests of 30 kratom products found lead and nickel above limits for oral daily drug intake, and that heavy users may be exposed many times over.

What people take it for, and what was found

Shown to help3

Limited

Pain

One small trial found cold pain tolerance rose 1 hour after kratom in men who used it daily. No trial in chronic pain was found.

The numbers and sources

Effect: In a randomized, placebo-controlled, double-blind study in which each man drank kratom and placebo decoctions in random order, pain tolerance on a cold pressor test rose from a mean of 11.2 seconds just before kratom to 24.9 seconds 1 hour after (p = 0.02). With the placebo drink it went from 15.0 to 12.0 seconds (p = 0.40) [1]. In a placebo-controlled, single-blind study of mitragynine, kratom's main alkaloid, mitragynine did not affect most measures at any dose. Pain tolerance was among those measures, and the abstract does not report it separately [2].
Population: 26 men, mean age 24.3, with a mean of 6.1 years of daily kratom use, during a 1-day inpatient stay [1]. 15 healthy volunteers in two parts of 8 and 7, given single doses [2].
Sources: [1], [2]
Caveats: A laboratory pain test in regular users, not chronic pain in patients. The standard deviation after kratom (39.4 seconds) was larger than the mean, so responses varied widely [1]. Both studies gave single doses. No trial in people with chronic pain was located.

Limited

Energy and focus

One small study found a low dose of mitragynine raised self-rated alertness and attention, while the highest dose raised self-rated amnesia.

The numbers and sources

Effect: In the placebo-controlled mitragynine study, the lowest of four doses raised self-rated arousal and attention, accuracy on a sustained attention task, and motor inhibition. The highest dose raised self-rated amnesia and produced mild psychopathological symptoms [2].
Population: 15 healthy volunteers, single doses [2].
Sources: [2]
Caveats: One small, single-blind study of purified mitragynine, not kratom leaf or extract products. Most outcomes did not change at any dose [2].

Limited

Mood and anxiety

Linked to small drops in momentary anxiety and, less consistently, sadness in the hours after use among regular users tracked by phone. No randomized trial was located.

The numbers and sources

Effect: In 357 US adults who used kratom at least 3 days a week, tracked by smartphone prompts for 15 days, kratom use in the prior 3 hours was linked to lower momentary anxiety than no use, and single use events to lower sadness. Use of prescribed anxiety or depression medicines did not change these links [23]. In the same sample, people named managing psychiatric and substance use problems as overall reasons for use [24]. In an online survey, 67% used kratom for anxiety and 65% for depression, and respondents gave it high ratings for these uses [21].
Population: 357 regular US kratom users [23][24]. 2,798 self-selected survey respondents [21].
Sources: [23], [21], [24]
Caveats: Observational studies of people who already use kratom and chose to take part. The authors describe the reductions in anxiety as small and call for randomized trials [23]. Self-ratings may reflect relief of withdrawal between doses.

Claimed, not studied in people1

Untested

Opioid withdrawal

Not studied in people in a trial. Users report less opioid withdrawal and craving, and mitragynine eased morphine withdrawal signs in rats. Kratom itself causes dependence and withdrawal.

No study in people. This rests on what users report, animal studies.

The numbers and sources

Effect: In an online survey of 2,798 kratom users, 1,144 (41%) said they used it to stop or cut down opioids, citing less opioid withdrawal and craving, and 411 reported more than a year without opioids that they attributed to kratom [21]. In morphine-dependent rats, mitragynine, kratom's main alkaloid, reduced acute withdrawal signs, while methadone and buprenorphine did so at smaller doses [22]. Regular kratom users also develop dependence and their own withdrawal symptoms [12][13].
Population: Self-selected online respondents, mostly in the US [21]. Morphine-dependent rats [22]. Regular kratom users [12][13].
Sources: [21], [22], [12], [13]
Caveats: Survey answers come from people who chose to respond and are not checked against any measure. No controlled trial of kratom for opioid withdrawal was located. Withdrawal from kratom itself is reported in the risk record on this page [12][13].

Risks

Reported risks12

Limited

FDA regulatory position

FDA states kratom is not appropriate for use as a dietary supplement, and lists reported liver toxicity, seizures and substance use disorder.

The numbers and sources

Effect: FDA states there are no FDA-approved kratom drugs, that kratom is not appropriate for use as a dietary supplement, and that kratom cannot be lawfully added to conventional foods. It lists reported serious adverse events including liver toxicity, seizures and substance use disorder, and states that a well-designed human abuse potential study has not been conducted [3].
Population: Kratom products sold in the US [3].
Sources: [3]
Caveats: A regulatory position, not a study of harm.

Limited

Adverse events in controlled trials

Small trials found dizziness, nausea and headache rising with dose, and no serious adverse events. Higher doses raised drug liking ratings.

The numbers and sources

Effect: In a randomized, double-blind, placebo-controlled trial of dried kratom leaf powder in healthy adults who had not used kratom, no serious adverse events or deaths were reported. Treatment-emergent adverse events generally rose with dose. Dizziness, nausea and a feeling of relaxation were most common after single doses, and headache, feeling hot, raised alanine aminotransferase (a liver enzyme) and nausea after 15 daily doses [6]. In the same trial, abuse-related adverse events were more frequent at higher doses, drug-effect ratings exceeded placebo only at the highest single dose, and no participant met thresholds for clinically meaningful opioid withdrawal [7]. In a randomized, double-blind trial in recreational drug users with opioid experience, somnolence, vomiting and nausea were the most common adverse events. Kratom constricted the pupils at every dose above the lowest, and the highest dose raised ratings of drug liking and feeling high [8].
Population: 116 adults aged 18 to 55, 49 on kratom across four dose levels and 67 on placebo, given single doses and then 15 daily doses [6][7]. 40 recreational polydrug users, 6 on kratom and 2 on placebo in each of five cohorts, given single doses [8].
Sources: [6], [7], [8]
Caveats: [6] and [7] report the same trial, of one product, in healthy adults screened to exclude certain liver enzyme gene variants [6]. The authors of [8] note that its results may not represent other kratom products. Trials of a few weeks cannot show the dependence, liver injury or deaths reported in long-term users.

Limited

Overdose deaths

Limited evidence: kratom was detected in 0.56% of US overdose deaths studied, mostly with other drugs such as fentanyl, and was the only substance in 7.

The numbers and sources

Effect: Of 27,338 US overdose deaths in 27 states from July 2016 to December 2017, kratom was detected in 152 (0.56%) and listed as a cause of death in 91. Kratom was the only substance detected in 7. Fentanyl was found in 65.1% of kratom-positive deaths [9]. In a review of 156 deaths in the UK and worldwide, 87% involved other substances and mitragynine alone was implicated in 23% [10].
Population: US death investigation data [9]. Mortality registers, databases and media reports [10].
Sources: [9], [10]
Caveats: The CDC notes that other substances cannot be ruled out in the 7 kratom-only deaths [9]. Death records cannot show how often kratom alone kills.

Limited

Poison center exposures

Case reports: US poison centers logged 1,807 kratom exposures from 2011 to 2017, with 11 deaths. Agitation and fast heart rate were most common.

The numbers and sources

Effect: From 2011 to 2017, US poison centers recorded 1,807 kratom exposures, 65% of them in 2016 and 2017. Of exposures with kratom listed first, 31.8% led to admission to a health care facility and 51.9% to a serious medical outcome. There were 11 deaths, 2 after kratom alone. Agitation (22.9%) and fast heart rate (21.4%) were the most common effects of kratom alone. Using other substances raised the odds of admission (OR 2.80) [11].
Population: Exposures reported to US poison centers [11].
Sources: [11]
Caveats: Poison center reports are voluntary and cannot give a rate of harm among all users.

Limited

Dependence and withdrawal

Limited evidence: in surveys of regular users, many met criteria for dependence or kratom use disorder, with withdrawal symptoms on stopping.

The numbers and sources

Effect: Among 293 regular users in Malaysia, more than half had severe dependence and 45% moderate dependence. Withdrawal included muscle spasms and pain, trouble sleeping, runny eyes and nose, hot flashes, fever, poor appetite and diarrhea [12]. Among 129 US adults who had used kratom, 29.5% met criteria for current kratom use disorder and 17.8% for remitted disorder. Withdrawal symptoms included gut upset, restlessness, anxiety, irritability, fatigue and craving [13].
Population: Community survey in Malaysia [12]. Online US convenience sample [13].
Sources: [12], [13]
Caveats: Cross-sectional surveys of self-selected users [12][13].

Limited

Withdrawal in newborns

Case reports: newborns developed withdrawal after their mothers used kratom in pregnancy. FDA states it is aware of such cases.

The numbers and sources

Effect: An infant born to a mother drinking kratom tea daily to self-treat opioid dependence developed neonatal abstinence syndrome [14]. US poison centers recorded 7 newborn exposures, 5 with withdrawal [11]. FDA states it is aware of neonatal abstinence syndrome after prenatal kratom exposure [3].
Population: Case report [14]. Poison center records [11].
Sources: [14], [11], [3]
Caveats: Case reports cannot give a rate.

Limited

Liver injury

Case reports: liver injury with jaundice after kratom, mostly improving after stopping, with four cases progressing to liver transplant.

The numbers and sources

Effect: The US Drug-Induced Liver Injury Network identified 11 cases of liver injury attributed to kratom, with a recent increase. All had jaundice, at a median of 14 days after starting. Most were hospitalized, and all recovered [15]. A 2026 systematic review of 31 studies found 32 cases of kratom-associated liver injury, mostly single-patient US case reports in adult men, often with other substances. Injury was mostly cholestatic and in most cases improved after kratom was stopped. Four progressed to liver transplantation [16].
Population: Prospective US liver injury registry [15]. Published case reports [16].
Sources: [15], [16]
Caveats: A registry of referred cases and published case reports, not a rate. Only 7 of the 32 published cases gave complete exposure details [16].

Limited

Lung injury

Case reports: 24 reports of lung outcomes after kratom exposure, including bleeding in the lungs and depressed breathing. All clinical patients survived.

The numbers and sources

Effect: A 2026 systematic review found 24 reports of lung outcomes after kratom, mitragynine or 7-OH exposure, 14 clinical and 10 forensic. They described diffuse alveolar hemorrhage (3), acute respiratory distress syndrome or diffuse lung injury (3), eosinophilic or hypersensitivity pneumonitis (2), central respiratory depression (6) and fluid or congestion in the lungs after death (10). All clinical patients survived. Attribution to kratom was graded probable in 9 reports, possible in 13 and unlikely in 2 [17].
Population: Case reports, conference abstracts and forensic series published through June 2026 [17].
Sources: [17]
Caveats: Case reports cannot give a rate. The authors describe their categories as provisional and hypothesis-generating [17].

Limited

Seizures

Case reports: 20 patients had seizures after reported kratom use. Reviewers found the evidence insufficient to show kratom causes them.

The numbers and sources

Effect: A 2025 systematic review found 11 publications describing 20 patients with seizures after reported kratom use. Only one had mitragynine measured in urine. Of 481 kratom reports in the FDA Adverse Event Reporting System, 22 (4.5%) involved seizure, and the CFSAN adverse event database held 18 seizure reports. The authors judged the evidence insufficient to show that kratom causes seizures [18].
Population: Case reports, case series, observational studies and FDA adverse event databases [18].
Sources: [18]
Caveats: Use was self-reported in 19 of the 20 patients, and no dataset gave amounts taken [18]. FDA lists seizures among reported serious adverse events [3].

Limited

Salmonella contamination

Case reports: a 2017 to 2018 Salmonella outbreak linked to kratom sickened 199 people in 41 states, and 38% of those with data were hospitalized.

The numbers and sources

Effect: A 2017 to 2018 Salmonella outbreak linked to kratom sickened 199 people in 41 states. Of 132 with information, 50 (38%) were hospitalized, and no deaths were reported. No single brand or supplier was identified [19].
Population: US outbreak investigation by CDC [19].
Sources: [19]
Caveats: The source could not be traced to one product [19].

Limited

Heavy metals

FDA states its tests of 30 kratom products found lead and nickel above limits for oral daily drug intake, and that heavy users may be exposed many times over.

The numbers and sources

Effect: FDA testing of 30 kratom products found lead and nickel at levels above the exposure limits for oral daily drug intake. FDA states heavy users may be exposed to many times the daily limit, with possible nervous system or kidney damage, anemia, high blood pressure and raised risk of certain cancers [20].
Population: 30 kratom products sold in the US [20].
Sources: [20]
Caveats: A 2019 product survey. Current products were not tested for this page.

Sources

Vicknasingam B, Chooi WT, Rahim AA, et al. Kratom and Pain Tolerance: A Randomized, Placebo-Controlled, Double-Blind Study. Yale Journal of Biology and Medicine. 2020. https://pubmed.ncbi.nlm.nih.gov/32607084/
Prevete E, Theunissen EL, Kuypers KPC, et al. An exploratory study of the safety profile and neurocognitive function after single doses of mitragynine in humans. Psychopharmacology. 2025. https://doi.org/10.1007/s00213-024-06734-2
U.S. Food and Drug Administration. FDA and Kratom. 2025. https://www.fda.gov/news-events/public-health-focus/fda-and-kratom
U.S. Food and Drug Administration. FDA Takes Steps to Restrict 7-OH Opioid Products Threatening American Consumers. News release. 2025. https://www.fda.gov/news-events/press-announcements/fda-takes-steps-restrict-7-oh-opioid-products-threatening-american-consumers
U.S. Food and Drug Administration. Hiding in Plain Sight: 7-OH Products. 2026. https://www.fda.gov/news-events/public-health-focus/hiding-plain-sight-7-oh-products
Huestis MA, Bothmer J, Hudzik T, Henningfield JE, Swift S. Safety and Tolerability of Single and Multiple Daily Oral Doses of Dried Kratom Leaf Powder in a Randomized Trial in Healthy Volunteers. Therapeutic Drug Monitoring. 2026. https://doi.org/10.1097/ftd.0000000000001427
Coe M, Huestis M, Wang D, et al. Assessment of Abuse Potential-Related Effects of Oral Dried Kratom Leaf Powder in Healthy Normal Participants Following Single and Multiple Daily Doses. Drug Testing and Analysis. 2026. https://doi.org/10.1002/dta.70089
Reissig CJ, Chen L, Nallani SC, et al. A Pilot, Dose-Finding, Pharmacodynamic and Pharmacokinetic Study of Orally Administered Botanical Kratom. Journal of Clinical Psychopharmacology. 2026. https://doi.org/10.1097/jcp.0000000000002158
Olsen EO, O'Donnell J, Mattson CL, et al. Notes from the Field: Unintentional Drug Overdose Deaths with Kratom Detected, 27 States, July 2016 to December 2017. Morbidity and Mortality Weekly Report. 2019. https://doi.org/10.15585/mmwr.mm6814a2
Corkery JM, Streete P, Claridge H, et al. Characteristics of deaths associated with kratom use. Journal of Psychopharmacology. 2019. https://doi.org/10.1177/0269881119862530
Post S, Spiller HA, Chounthirath T, et al. Kratom exposures reported to United States poison control centers: 2011 to 2017. Clinical Toxicology. 2019. https://doi.org/10.1080/15563650.2019.1569236
Singh D, Müller CP, Vicknasingam BK. Kratom (Mitragyna speciosa) dependence, withdrawal symptoms and craving in regular users. Drug and Alcohol Dependence. 2014. https://doi.org/10.1016/j.drugalcdep.2014.03.017
Smith KE, Dunn KE, Rogers JM, et al. Assessment of Kratom Use Disorder and Withdrawal Among an Online Convenience Sample of US Adults. Journal of Addiction Medicine. 2022. https://doi.org/10.1097/adm.0000000000000986
Eldridge WB, Foster C, Wyble L. Neonatal Abstinence Syndrome Due to Maternal Kratom Use. Pediatrics. 2018. https://doi.org/10.1542/peds.2018-1839
Ahmad J, Odin JA, Hayashi PH, et al. Liver injury associated with kratom, a popular opioid-like product: Experience from the U.S. drug induced liver injury network and a review of the literature. Drug and Alcohol Dependence. 2021. https://doi.org/10.1016/j.drugalcdep.2020.108426
Calicdan XA, Kopczynski A, Medina E, et al. Liver Injury Associated With Kratom (Mitragyna speciosa): A Systematic Review. Journal of Addiction Medicine. 2026. https://doi.org/10.1097/adm.0000000000001663
Kanchustambham V, Saladi S. Kratom-Associated Pulmonary Toxicity: A Systematic Review of Case Reports and Forensic Series with a Proposed Clinical Phenotype Classification. Journal of Medical Toxicology. 2026. https://doi.org/10.1007/s13181-026-01153-5
Turla T, Abele G, Hua M, Paustenbach D. Reported associations between kratom and seizures: a systematic review. Frontiers in Pharmacology. 2025. https://doi.org/10.3389/fphar.2025.1632835
Centers for Disease Control and Prevention. Multistate Outbreak of Salmonella I 4,[5],12:b:- Infections Linked to Kratom Products (Final Update). 2018. https://archive.cdc.gov/www_cdc_gov/salmonella/kratom-02-18/index.html
U.S. Food and Drug Administration. Laboratory Analysis of Kratom Products for Heavy Metals. 2019. https://www.fda.gov/news-events/public-health-focus/laboratory-analysis-kratom-products-heavy-metals
Garcia-Romeu A, Cox DJ, Smith KE, et al. Kratom (Mitragyna speciosa): user demographics, use patterns, and implications for the opioid epidemic. Drug and Alcohol Dependence. 2020. https://doi.org/10.1016/j.drugalcdep.2020.107849
Hassan R, Pike See C, Sreenivasan S, et al. Mitragynine attenuates morphine withdrawal effects in rats: a comparison with methadone and buprenorphine. Frontiers in Psychiatry. 2020. https://doi.org/10.3389/fpsyt.2020.00411
Timmons P, Daniulaityte R, Panlilio LV, et al. Associations between kratom (Mitragyna speciosa) use and real-time anxiety and sadness: a 15-day ecological momentary assessment study. Drug and Alcohol Dependence. 2026. https://doi.org/10.1016/j.drugalcdep.2026.113383
Smith KE, Panlilio LV, Feldman JD, et al. Ecological momentary assessment of self-reported kratom use, effects, and motivations among US adults. JAMA Network Open. 2024. https://doi.org/10.1001/jamanetworkopen.2023.53401

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