Opioid receptors and legal highs:Salvia divinorumand Kratom

Abstract

Salvia divinorum and Mitragyna speciosa ("Kratom"), two unscheduled dietary supplements whose active agents are opioid receptor agonists, have discrete psychoactive effects that have contributed to their increasing popularity. Salvia divinorum contains the highly selective kappa- opioid receptor agonist salvinorin A; this compound produces visual hallucinations and synesthesia. Mitragynine, the major alkaloid identified from Kratom, has been reported as a partial opioid agonist producing similar effects to morphine. An interesting minor alkaloid of Kratom, 7-hydroxymitragynine, has been reported to be more potent than morphine. Both Kratom alkaloids are reported to activate supraspinal mu- and delta- opioid receptors, explaining their use by chronic narcotics users to ameliorate opioid withdrawal symptoms. Despite their widespread Internet availability, use of Salvia divinorum and Kratom represents an emerging trend that escapes traditional methods of toxicologic monitoring. The purpose of this article is to familiarize toxicologists and poison control specialists with these emerging psychoactive dietary supplements.

In the evidence

This study is part of the evidence base for a synthesis in the library. Here is how each one recorded it.

• State of the evidence: Salvia divinorum ↑Supports

  Reports that salvinorin A is a highly selective kappa-opioid agonist producing visual hallucinations and synesthesia, and that such supplements escape traditional toxicologic monitoring.

  Synthesized November 1, 2026

Comparable studies

Other narrative reviews on salvia divinorum, most cited first.