Mitragynine is the primary psychoactive alkaloid in Mitragyna speciosa (kratom), a Southeast Asian tree in the coffee family. Mitragynine makes up approximately 60–70% of the total alkaloid content in kratom leaf and is the compound primarily responsible for kratom's stimulant effects at low doses and its sedative, analgesic effects at higher doses. It works through a complex mechanism that includes partial agonism at mu-opioid receptors (much weaker than classical opioids) and interaction with adrenergic and serotonergic receptors, which together produce kratom's unusual dose-dependent biphasic effects.

How does mitragynine differ from 7-hydroxymitragynine?

7-Hydroxymitragynine (7-OH-mitragynine) is a minor alkaloid present in kratom leaf in small amounts (under 2% of alkaloid content), but it is significantly more potent at opioid receptors than mitragynine — estimated to be 13x more potent than morphine at mu-opioid receptors, compared to mitragynine's much weaker activity. In whole kratom leaf, 7-OH-mitragynine contributes substantially to the analgesic and sedative effects despite its low concentration. Some processed kratom extracts deliberately concentrate 7-OH-mitragynine. The FDA and DEA have raised concerns about 7-OH-mitragynine specifically due to its opioid receptor potency.

Why does mitragynine have different effects at different doses?

Kratom's biphasic dose-response is one of its defining characteristics: at low doses (1–5g of leaf powder), stimulant effects dominate — increased energy, focus, and sociability, mediated through adrenergic pathways. At higher doses (5–15g), opioid receptor partial agonism becomes more prominent, producing sedation, pain relief, and anxiolysis. This is why kratom users describe it as acting like coffee at low doses and more like a mild opioid at higher doses. This biphasic pattern is unusual and dose-dependent, making standardization difficult.

Is mitragynine safe?

Mitragynine is not FDA-approved for any medical use. Regular, heavy kratom use carries dependence risk, and abrupt cessation can produce withdrawal symptoms (sweating, irritability, muscle aches, insomnia). The substance exists in a legal gray area in the US — legal federally but banned in several states and cities. Kratom products should come with third-party lab testing. Find lab-tested kratom products at Elevated Haze.