Pharmacologic and clinical assessment of kratom: An update

Am J Health Syst Pharm. 2019 Nov 13;76(23):1915-1925. doi: 10.1093/ajhp/zxz221.


Purpose: This article presents updated information on kratom (Mitragyna speciosa), a natural opioid with stimulant properties that is currently sold in the United States without a prescription.

Summary: Kratom exerts opioid and alpha-2 agonistic effects, as well as anti-inflammatory and mild stimulant effects. Respiratory depression has not been commonly reported, but kratom does cause a host of adverse effects. While kratom may have a role in patients who are in chronic pain or dependent on opioid painkillers or heroin, this needs to be established in clinical trials. Kratom may have drug interactions as both a cytochrome P-450 system substrate and inhibitor. Kratom does not appear in normal drug screens and, especially when ingested with other substances of abuse, may not be recognized as an agent of harm. There are numerous cases of death in kratom users, but many involved polypharmaceutical ingestions. There are assessments where people have been unable to stop using kratom therapy and withdrawal signs/symptoms occurred in patients or their newborn babies after kratom cessation. Both banning and failure to ban kratom places people at risk; a middle-ground alternative, placing it behind the pharmacy counter, might be useful.

Conclusion: Kratom has a unique pharmacologic profile that might offer advantages over other opioids, but its high abuse liability, potential for drug interactions and adverse events, and inadequate research into the balance of benefits to harm are concerning. There is mounting information on the adverse events associated with kratom use and potential treatments that can be useful to clinicians.

Keywords: Mitragyna speciosa; herb; kratom; opioid; withdrawal.

Publication types

  • Review

MeSH terms

  • Analgesics, Opioid / administration & dosage
  • Analgesics, Opioid / adverse effects*
  • Analgesics, Opioid / pharmacokinetics
  • Biological Products / administration & dosage
  • Biological Products / adverse effects*
  • Biological Products / pharmacokinetics
  • Chronic Pain / drug therapy*
  • Clinical Trials as Topic
  • Humans
  • Mitragyna / chemistry*
  • Opiate Substitution Treatment / methods
  • Opioid-Related Disorders / etiology
  • Opioid-Related Disorders / prevention & control*
  • Substance Withdrawal Syndrome / drug therapy
  • Substance Withdrawal Syndrome / etiology


  • Analgesics, Opioid
  • Biological Products