Scott Gottlieb, commissioner of the Food and Drug Administration, testifies at a House Energy and Commerce Committee hearing last month on federal efforts to combat the opioid crisis. On Tuesday, the FDA issued a public health warning saying there was no evidence that the herb kratom was effective in treating opioid addictions. (Drew Angerer/Getty Images)

The Food and Drug Administration issued a strong warning Tuesday to consumers to stay away from the herbal supplement kratom, saying regulators are aware of 36 deaths linked to products containing the substance.

Consumers are increasingly using the supplement, which comes from a plant in Southeast Asia, for pain, anxiety and depression, as well as symptoms of opioid withdrawal. The herb also is used recreationally because it produces symptoms such as euphoria.  Proponents say it is a safe way to deal with chronic pain and other ailments, and some researchers are exploring its therapeutic potential, including helping people overcome addictions.

But in a statement, FDA Commissioner Scott Gottlieb said that there is no “reliable evidence” to support the use of kratom as a treatment for opioid-use disorder, and that there are no other FDA-approved uses for kratom.

Rather, he said, evidence shows that the herb has similar effects to narcotics like opioids, “and carries similar risks of abuse, addiction and, in some cases, death.” He said that calls to U.S. poison control centers involving kratom increased tenfold between 2010 and 2015, and that the herb is associated with side effects including seizures, liver damage and withdrawal symptoms.

Last year, the Drug Enforcement Administration proposed temporarily placing the drug into Schedule 1 of the Controlled Substances Act, which effectively would have banned its use. But the agency backtracked after a public outcry and pressure from some members of Congress. It asked the FDA to expedite a scientific and medical evaluation — including whether kratom has any medical use —  and a recommendation for how to handle the compounds in kratom.

DEA spokesman Melvin Patterson said Tuesday that once the agency receives FDA's report, it will decide whether kratom should be regulated as a controlled substance and if so, into which schedule, or classification, it should be placed.

The herb is banned in several states, including Alabama, Arkansas, Indiana, Tennessee and Wisconsin. Gottlieb said the FDA is treating kratom as an unapproved drug and also has taken action against kratom-containing dietary supplements. If the plant is useful in treating various conditions, a manufacturer should go through the agency's regular drug-approval process to prove the product is safe and effective, he added. Meanwhile, the FDA is working to prevent shipments of kratom from entering he country.

Jack Henningfield, an addiction specialist who works at the drug policy consulting group Pinney Associates, which has done work for the American Kratom Association, said that surveys have shown that people using opioids to treat pain or satisfy an addiction were able to stop using them by drinking kratom tea. He argued that kratom's “overall abuse potential and risk of death isn't anything close to narcotics like opioids” and warned that restricting or banning the substance could drive some people back to opioids or onto the black market to get kratom.

In a study last year for the American Kratom Association, Henningfield, an adjunct professor of behavior policy at Johns Hopkins,  found that effectively banning kratom “is not warranted from a public health perspective and is more likely to cause public health problems that do not exist.”

The American Kratom Association says on its website that kratom is not habit forming but that if taken in high amounts over long periods of time, consumers may experience a dependence similar to caffeine dependence.

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