Kratom, a Thai medicinal plant known scientifically as Mitragyna speciosa, is often taken in the form of capsules containing dried, pulverized leaves. Photo credit: Shutterstock

The U.S. Food and Drug Administration released a statement on Tuesday afternoon from Commissioner Scott Gottlieb, MD, declaring that kratom, a southeast Asian herbal medicine, contains naturally-occurring plant alkaloid chemicals that are predicted by unpublished computer models to be opioids.

The agency has also collected 44 fatal adverse reaction reports where kratom components were present in the bodily fluids of the decedents.

As a result, the agency is heightening its warning to consumers and healthcare professionals, first made in a public health advisory last November, that kratom presents a safety hazard and holds the potential for abuse.

But consumers sing kratom’s praises as a medicinal herb useful for chronic pain, anxiety and depression. The herb, often used as a tea or in capsules containing pulverized dried leaves, is used by others who had been previously dependent on prescription opioids or alcohol. But the FDA states that no scientific studies support these therapeutic uses of kratom, with Dr. Gottlieb’s statement concluding by urging people who are self-medicating with kratom to seek the help of healthcare professionals and prescription opioid-maintenance therapy or non-opioid pain relievers.

When the Drug Enforcement Agency announced plans in 2016 to add the two major kratom components to the most-restrictive Schedule I of U.S controlled substances–the classification for drugs with no medical utility and high abuse potential–the general public and members of Congress objected so vigorously that the agency rescinded its plan. In a subsequent comment period, the DEA received 23,000 comments with 99% voicing positive views on the herb.

Along with Tuesday’s FDA warning, the agency also released a 164-page document (PDF) with case details on 28 deaths where kratom was present, first referred to in their November 2017 advisory. This report joins another from December showing details of 8 other deaths (PDF). Nick Wing, a Huffington Post senior reporter, dissected these fatal adverse reaction reports and found that in many, kratom and its constituents were likely innocent bystanders. The agency even includes among kratom-associated deaths cases of fatalities by hanging, gunshot and others where kratom was adulterated with the active metabolite of a prescription opioid, O-desmethyltramadol.

My take? If Dr. Gottlieb’s statement were a pharmacology graduate student’s written qualifying exam answer to a question seeking an objective assessment of kratom pharmacology and toxicology, I’d have no choice but to issue a failing grade.

I would tell the student:

• You failed to read 20 years of published scientific literature on alkaloids present in the kratom plant, Mitragyna speciosa.
• You failed to demonstrate any mastery of current research on the biochemical pharmacology of opioids.
• You were overly reliant on unpublished data from a computational model in the absence of direct, experimental confirmation.
• You made safety conclusions based on confirmation bias and a poor assessment of adverse reaction reports where kratom or its constituents were present.
• You also made safety conclusions in the absence of considering the impact on public health if kratom were banned.
• You concluded that the substance has no medical benefit in the absence of a prospective clinical trial for any indication with a well-qualified kratom product or purified kratom alkaloid.