It's an herb derived from the leaves of a plant related to the coffee tree.
Users say it's a safe and effective treatment for chronic pain, anxiety, depression and addiction.
Federal authorities appear to be getting ready to crack down on the botanical drug.
... [We must] protect the public from addictive substances like kratom, both as part of our commitment to stemming the opioid epidemic and preventing another from taking hold. Scott Gottlieb, FDA commissioner