Category: Toxicology
Keywords: Kratom, Novel psychoactive substance, mitragyna (PubMed Search)
Posted: 3/4/2026 by Kathy Prybys, MD
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Bottom Line:
Kratom is an herbal extract used as an alternative medicine and recreational substance with marked increase in use over recent years. Kratom contains a complex mixture of psychoactive ingredients with effects at multiple receptors (mu, serotonin, dopamine, and alpha-adrenergic receptors) and causes stimulant effects at lower doses and opioid effects at higher doses. Depending on the predominant clinical effects, treatment with naloxone, benzodiazepine, and labetalol have been reported.
Kratom is an herbal extract from the leaves of trees of the Mitragyna speciosa native to Southeast, containing a complex mixture of psychoactive ingredients with effects at multiple receptors (mu, serotonin, dopamine, and alpha-adrenergic). Clinical effects are dose dependent with stimulant effects seen at lower doses and opioid effects at higher doses. The two predominate alkaloid psychoactive ingredients (mitragynine and 7-hydroxymitragynine) have partial agonist effects at the mu opioid receptor with reported analgesic effect of the potency of codeine.
Use of kratom has increased markedly in recent years in both the US and European countries as a popular alternative medicine for treatment of pain, mood disorders, opioid withdrawal, and for recreational use.
Leaves are crushed and smoked, brewed, put into capsules, tablets, powder, or liquid extracts and are available from online, head shops, health food stores, and some gas stations. In the US, Kratom is not an FDA approved drug product thus not federally regulated. The FDA warns that there is no standard dose, products may be contaminated, and it is not thoroughly studied. Kratom products may be falsely disguised and sold as other products such as potpourri or incense.
In reported overdose cases, a mixture of opioid-like symptoms (depressed CNS) and sympathetic and serotonin syndromes (HTN, tachycardia, miosis, agitation, seizure) were reported and treated with naloxone, benzodiazepines, and labetalol. Urine drug screen will not detect Kratom.
A new concentrated product called 7-hyroxymitragynine (aka “7 hydroxy” or “7 OH”) is sold in pill form and is more potent that morphine and has led to respiratory depression requiring naloxone.
Mitragyna speciosa (Kratom) poisoning: Findings from ten cases. Peran, D, Stern, M, et al. Toxicon.2023. Vol 225. https://doi.org/10.1016/j.toxicon.
Deaths in Colorado Attributed to Kratom. Gersham K., Timm K., et al. New England Journal of Medicine. 2019. Vol 380 (1). 99-98. https://www.nejm.org/doi/full/10.1056/NEJMc1811055
Kratom exposures among older adults reported to U.S. poison centers, 2014-2019. Graves JM, Dilley JA, et al. J Am Geriatr Soc. 2021. Aug;69(8):2176-2184. doi: 10.1111/jgs.17326. Epub 2021 Jun 18. PMID: 34143890.
Kratom Use and Toxicities in the United States. Pharmacotherapy. Eggleston W, Stoppacher R, et al. 2019 Jul;39(7):775-777. doi: 10.1002/phar.2280. Epub 2019 Jun 13. PMID: 3109903
Additional Fatal Overdoses Tied to Synthetic Kratom in Los Angeles Countyhttp://publichealth.lacounty.gov/phcommon/public/media/mediapubhpdetail.cfm?prid=5156
