In April, we reported on an FDA order to remove some kratom products from the market because of Salmonella contamination. That turned out to be the opening shot in a war that the federal government has declared on the herbal product -- or, at least, that's how kratom's advocates see it. In this story, we review what has happened since with the opioid mimic and the government's efforts to discourage its use.

Kratom comes from an Asian plant, Mitragyna speciosa, that has long been a mild recreational drug and part of folk remedies. In recent years, it has gained a following in North America with claims that it can relieve pain that conventional drugs can't touch, and that it can also relieve symptoms of opioid withdrawal. It's sold in smoke shops, "alternative medicine" storefronts, and, of course, online from countless vendors.

Its mechanism of action isn't entirely clear. That's partly because it's an herbal product with dozens of possible active compounds. However, attention has focused on two alkaloids that bind to mu-opioid receptors, which are also the target for conventional opioids. But its activity is also different from opium derivatives, earning it the moniker "atypical opioid."

The FDA has made no secret of its wish that kratom would simply go away. The agency's ability to regulate herbal products is limited to ensuring safety and to prevent vendors from making overt unapproved health claims. But when it comes to kratom, the agency has pulled both of those levers as hard as it can.

'No Proven Medical Uses'

Since that recall notice was issued April 3, the FDA pushed additional vendors of kratom products to pull products for safety reasons, some because of actual positive results on Salmonella tests and others "out of an abundance of caution." The CDC also joined the effort, identifying nearly 200 individuals who developed Salmonella infections tied to kratom, including 50 who were hospitalized. Although the CDC declared the outbreak over on May 24, the FDA continued to issue recall announcements related to Salmonella for more than a month afterward.

In May, the FDA also took the campaign in a different direction, accusing three sellers of kratom products of making unapproved health claims. These companies, according to the agency, had asserted their kratom products had the "ability to help in the treatment of opioid addiction and withdrawal. The companies also make claims about treating pain, as well as other medical conditions like lowering blood pressure, treating cancer and reducing neuron damage caused by strokes."

Perhaps concerned that the actions might be misinterpreted, FDA Commissioner Scott Gottlieb, MD, issued a lengthy statement in early July explaining the agency's Salmonella testing procedures and also his thinking about kratom in general. "As we have previously stated, there are no proven medical uses for kratom and the FDA strongly discourages the public from consuming kratom," Gottlieb said, adding, "Kratom is an inherently addictive product that can cause harm, which is reason enough not to consume it." A few days later, in another lengthy statement about opioid addiction generally, Gottlieb lumped kratom together with fentanyl as dangerous products often shipped through the mail.

Another batch of warning letters for unapproved health claims went out in early September. In announcing them, Gottlieb hammered on the lack of "well-controlled scientific studies" to demonstrate kratom's effectiveness for relieving pain or opioid withdrawal symptoms, or on how it may interact with other agents and the adverse effects that could result. "We cannot allow kratom products with unsubstantiated claims to prevent those with [opioid use disorder] from seeking treatments that have been demonstrated to be safe and effective," he thundered.

In late November, the FDA raised another concern with kratom: "disturbingly high levels of heavy metals in kratom products," an FDA release said. "Among the heavy metals we found were lead and nickel at levels not considered safe for human consumption."

Schedule I Ban?

But the biggest impact the FDA has made on actual kratom use went unmentioned in the agency's many press releases over the year. In 2012 and 2014, the agency included kratom on so-called import alerts for drugs and drug ingredients that are illegal to import. These alerts authorize federal agents to seize products at ports of entry. A Feb. 26 web posting noted several seizures occurring in 2014 and 2016, but nothing more recent.

But kratom consumers say they've found it increasingly difficult to find the product for sale, and they blame the import alerts for drying up supplies. At the online Pain News Network, a Nov. 16 article quoted the head of the American Kratom Association -- an advocacy group for vendors and customers -- as saying several suppliers had reported having tons of the product confiscated. The article's headline, and the advocacy group's leader, used the term "shadow ban" to describe the import crackdown.

The article's readers confirmed the difficulty in obtaining kratom. "Two of my main suppliers that I have done business with for years told me and they lost thousands," one wrote in the comments section.

An actual ban may also be coming. The Drug Enforcement Administration has been considering designating kratom as Schedule I, which would make it illegal to sell, manufacture, import, or possess. In early November, the Department of Health and Human Services sent the DEA a letter supporting such a designation.

Whether or when the DEA will reach a decision is unclear. The agency had previously announced its intention in 2016 to implement a Schedule I ban, but backed away after consumers and vendors objected that there was no scientific basis for such a move. However, the HHS declaration that kratom has no medical value and is dangerous gives the DEA more cover for a ban.

The online science-and-culture publication Inverse reported in November that the DEA appears to have made up its mind to take the step, but is still crafting an announcement. When the publication asked a DEA spokesman how the agency will rule, the response was: "I think that there's a good indication based on what we already heard from [Health and Human Services], what they've provided, and what Dr. Gottlieb has been saying... That should have given everybody a good idea."