Some proponents say the drug can help people withdraw from opioid dependency. However, there are still a number of concerns about the substance.

Are the leaves from a Southeast Asian tree the next important weapon in the fight against America’s opioid epidemic?

Kratom (Mitragyna speciosa) has been used traditionally in places like Thailand and Myanmar for centuries as an analgesic and recreational drug.

Now, its proponents in the United States argue that it is invaluable in helping people get through opioid withdrawal.

However, kratom’s checkered legal past and its current status as an unregulated herbal supplement have left many, including members of law enforcement and the medical field, uncertain about it.

In fact, the Food and Drug Administration (FDA) issued a “public health advisory” on November 14 about kratom.

Agency officials said they were concered about the product’s “deadly risks.” They said it’s “very troubling” that people think they can use kratom to treat opioid withdrawal symptoms.

Nonetheless, researchers who study kratom say the product has some beneficial uses.

Opioids may be the gold standard in pain relief, but they come with some serious side effects.

Addiction is one.

The second is respiratory depression, which includes slow, shallow breathing and even a stoppage of breathing entirely. These conditions can lead to a fatal overdose.

“If you could come up with a drug that either got rid of the addiction liability or got rid of the respiratory depression… you would have a serious leg up on what’s out there right now,” Andrew Kruegel, PhD, an associate research scientist in the department of chemistry at Columbia University in New York, told Healthline.

That’s where kratom comes in.

Kruegel has studied the chemistry involving the plant’s effects on the brain and calls the substance “an atypical opioid” that differs from traditional opioids in how it interacts with the brain.

When opioids are present in the blood stream, they eventually find their way to the brain. There they bind with receptors, causing a cascade of effects that include pain relief.

However, Kruegel says, we can’t think of it simply like a binary on/off switch.

The receptors in the brain can be activated in different ways, what’s called “biased signaling.”

The main components in kratom responsible for its analgesic effects are two alkaloids called mitragynine and 7-hydroxymitragynine.

They can activate the brain in such a way that they provide pain relief without, or at least with less, respiratory depression.

The compounds in kratom are also classified as “partial agonists,” meaning, in Kruegel’s words: “They don’t turn on the receptor as fully as you would with morphine or fentanyl, for example. You only get a partial response. That is also protective in terms of respiratory depression side effects.”

Beyond kratom’s potential for use as a painkiller, it’s found a following among users in the United States who swear by its ability to help kick opioid habits. Research in medical journals has also pointed out that “individuals in the United States are increasingly using kratom for the self-management of pain and opioid withdrawal.”

Online forums like Reddit are filled with testimonials by individuals swearing that kratom helped them turn their lives around from opioid addiction.

VICE News documented, and recently aired, a heroin addict’s struggle as he fought to overcome his addiction by using kratom.

The problem for now, says Kruegel, is that, on paper, there’s a dearth of clinical evidence to support the many anecdotal stories about the profound benefits of the drug.

“If you read these anecdotal reports, it’s quite striking. It makes you think there’s something there,” said Kruegel. “It certainly leads you to believe that there is more research to be done.”

But, even as many swear by the drug, it has also been haunted by reports about its danger.

In fact, almost exactly one year ago, federal officials were on the verge of banning the substance in the United States entirely. Up until September 2016, the drug existed as an unregulated supplement, often peddled in head shops.

But after reports — including one by the Centers for Disease Control and Prevention (CDC), which stated the number of calls to poison control centers about kratom increased tenfold in a five-year period from 26 in 2010 to 263 in 2015 — the drug could no longer fly under the radar.

The report called the drug “an emerging public health threat.”

The Drug Enforcement Administration (DEA) proposed to move kratom to a Schedule I drug, the most restrictive scheduling that includes LSD and heroin. Schedule I drugs are considered to have “no currently accepted medical use and a high potential for abuse.”

However, the DEA ultimately dropped their plan after pushback from the research community and a grassroots movement among kratom users.

“We backed them down,” said Kruegel.

“That was a big surprise to see: how large the community of [kratom] users is,” he added. “Also, to see how fervently they feel about how this has really turned around their lives. Not just for people who are dealing with addiction, but also for all these chronic pain syndromes and for mood disorders like depression and anxiety.”

Moving kratom to a Schedule I drug would have effectively “killed all research in the field,” Kruegel said.

Despite kratom remaining legal, if unregulated, it is still a contentious substance both in the United States and abroad. Even in Southeast Asia, where it grows, it remains illegal in several countries, including Thailand and Malaysia.

In the United States, kratom is sold as a nutritional supplement, so it is unregulated by the Food and Drug Administration (FDA).

What that means is: Buyer beware.

CNN recently reported on analyzed samples from emergency room patients of kratom that had been spiked with other opiates, including morphine and oxycodone.

An FDA-approved drug synthesized from kratom isn’t even on the horizon at this point.

“I want to emphasize that we don’t know that much about it,” said Kruegel. “What data we do have seems to indicate it’s very promising and I’d like to see more research on the subject and avoid any kind of regulatory framework that would kill that.”