Pharmacology · April 2026
Is kratom an opioid?
Direct answer
Kratom activates mu-opioid receptors — it is pharmacologically an opioid. But it is an atypical opioid: a partial agonist with biased G-protein signaling and a lower respiratory depression ceiling than classical opioids like morphine. Legally, it is not scheduled as a controlled substance at the US federal level. "Opioid" in the medical sense and "scheduled opioid" in the legal sense are different things.
The pharmacology
An "opioid" is any molecule that activates mu, kappa, or delta opioid receptors. Mitragynine and 7-hydroxymitragynine — kratom\'s two primary alkaloids — are both mu-opioid partial agonists. By biochemistry, they are opioids.
What makes kratom different from morphine or heroin:
- Partial agonism: caps the maximum receptor activation. Morphine is a full agonist.
- Biased signaling: favors G-protein pathway (analgesia) over β-arrestin (respiratory depression).
- Mixed pharmacology: kratom also modulates alpha-adrenergic and serotonergic systems — a more complex signature than classical opioids.
This is why kratom overdose fatality rates are substantially lower than heroin or fentanyl. It is not impossible — combinations with alcohol, benzos, or 7-OH products still carry real risk — but the ceiling exists.
The legal status
Federally in the US, kratom is NOT a controlled substance. It is a botanical. The FDA and DEA have publicly discussed scheduling (most notably the 2016 DEA notice of intent), but no federal scheduling has occurred.
State-level scheduling varies: banned in 6 states (AL, AR, IN, RI, VT, WI), regulated under the KCPA in 5 (AZ, GA, NV, OK, UT), legal in the remaining 39.
What this means practically
- Kratom can produce opioid-type dependence. It is real and should be respected.
- Combining kratom with other opioids compounds respiratory depression — do not do it.
- Naloxone (Narcan) reverses kratom overdose, same as any opioid.
- Standard opioid drug tests do NOT detect kratom.
- "Kratom is not an opioid" is a common marketing claim but is pharmacologically inaccurate.
The 7-OH distinction
Isolated 7-hydroxymitragynine products (shots, tablets) are much closer to classical opioid pharmacology than leaf kratom. The distinction between "leaf kratom" and "7-OH products" matters pharmacologically, legally, and medically. See our 7-OH hub.
FAQ
So is kratom an opioid or not?
Yes, pharmacologically — mitragynine is a mu-opioid receptor partial agonist. No, legally — it is not scheduled as an opioid under the Controlled Substances Act at the federal level. Both can be true.
Can you get addicted to kratom like heroin?
Less severely. Kratom dependence is real and uncomfortable to withdraw from, but the respiratory depression ceiling, biased agonism, and lower euphoric peak produce a less severe addiction profile than classical opioids. Leaf kratom withdrawal resolves in 7–10 days; heroin withdrawal is longer and more severe.
Will Narcan reverse a kratom overdose?
Yes — naloxone (Narcan) reverses mu-opioid activity and is effective against kratom-induced respiratory depression. If you suspect an overdose, call 911 and use Narcan if available. This is the same protocol as for any opioid overdose.
Does kratom show up as an opioid on drug tests?
No. Standard 5-panel and 10-panel opioid immunoassays do NOT detect mitragynine. A specific kratom-targeted panel (sometimes used by pain clinics) can detect it. Morphine/heroin panels will not.
Is 7-OH more opioid-like than mitragynine?
Significantly more. 7-OH has ~13× higher mu-opioid receptor affinity than mitragynine and its biased-agonism profile shifts toward classical opioid pharmacology. Isolated 7-OH products are pharmacologically closer to oxycodone than to leaf kratom.