Kratom users can legally buy, sell and use the popular Southeast Asian tree leaf product for at least a few more days in the United States.

The product, typically brewed as tea or taken in pills, will not become an illegal Schedule I substance on Friday, the first day the looming designation could have taken effect pursuant to an emergency scheduling announcement that surprised users last month.

It's "highly accurate" to believe the ban won't take effect next week either, Drug Enforcement Administration spokesman Russ Baer says.

Kratom advocates have staged an energetic campaign aimed at convincing the DEA to abandon a planned ban announced on Aug. 30, saying the product is often used as a near-miraculous treatment for pain, depression and drug addiction.

In anticipation of the ban, online kratom commerce has ground to a halt, with some merchants left with hundreds of thousands or millions of dollars' worth of unsold supply.

Yet while advocates may see a glimmer of hope in the fact the ban hasn't taken effect, the DEA assures it still will.

"We have determined that it represents an imminent hazard, so we're not going to drag our feet very long," Baer says. "It's not a matter of if, it's just a matter of when."

Baer says the DEA's Diversion Control Division is preparing a final order, which will include a description of scientific evidence supporting a temporary ban – lasting two or three years – and an outline of criminal sanctions.

"They're still working through those documents, and it takes awhile," Baer says. "Even after we've compiled the documents and we've pushed the paper over to the Federal Register, a different agency, they have to do some formatting and it will take a couple days at least to publish."

Dozens of House lawmakers and a handful of senators have asked the DEA to consider stalling to allow for a standard public notice and comment period. In this case, the DEA invoked emergency scheduling powers, citing an imminent threat to public safety.

Though the agency intends to move forward with the ban, it has not explicitly ruled out resubmitting the proposal for public notice and comment.

The DEA justifies the ban by saying that the drug sometimes can be addictive and that it has been associated with 15 deaths in recent years in the U.S., though advocates claim in at least 14 cases other drug use appears to have been involved.

"Our review of the scientific literature," Baer says, indicates kratom "does in some cases produce psychosis, does produce hallucinations, delusions, does result in some cases in respiratory depression, physical withdrawal and in severe cases, death."

Kratom users and some scientists, however, dispute the notion that such effects are common or attributable solely to kratom use, and say the true threat to public safety is removing from the market a relatively safe herbal off-ramp from heroin and legal painkiller addiction.

The ban would eliminate a substantial harm-reduction option for recovering addicts of other substances, advocates say, and once stockpiled supplies dry up, people will buy more on the black market without being able to hold vendors accountable for what's in the product.

Susan Ash, founder of the American Kratom Association, estimates that 60 percent of kratom users have no history of addiction and instead use the plant as a non-pharmaceutical option for pain relief, mood improvement or an energy boost.

Ash repeatedly has stressed that many people recovering from addictions to other substances, herself included, aren't sure what they would do without the product, which they insist does not cause a high or the life-inhibiting effects of their formerly abused drugs.

AKA Executive Director Paul Pelosi Jr. has estimated that as many as 4 or 5 million Americans may be using kratom, based on his understanding of industry sales figures.

Some kratom users have reported that it can be addictive and that cessation can result in withdrawal symptoms – though many also insist they never have felt the grasp of addiction or negative symptoms when abruptly stopping use.

Among those campaigning to keep kratom legal are scientists such as Andrew Kruegel, an associate research scientist at Columbia University. He says as part of research that needed to be completed before the ban takes effect, he was boiling in alcohol his stash of kratom to convert it into non-scheduled analogs of the two compounds the DEA specifically is prohibiting, effectively banning the plant: mitragynine and 7-hydroxymitragynine.

Kreugel told U.S. News research suggests the two compounds result in different effects than traditionally abused opioids, appearing only to be partial agonists of the mu opioid receptor – with a ceiling effect regardless of dose – and that they also appear to be biased agonists, meaning they activate what is called the G protein pathway but not a separate opioid pathway associated with constipation and respiratory depression, a primary cause of overdose deaths.

"In animal studies, both mitragynine and 7-hydroxymitragynine produce almost no respiratory depression," Kreugel said. "Of course this hasn't been rigorously studied in humans because there have been no clinical trials, but anecdotal evidence – which is quite substantial – suggests that people aren't dying of respiratory depression."

Kruegel said mitragynine and 7-hydroxymitragynine preliminarily appear "similar in terms of pharmacology" to a drug called Oliceridine that is undergoing Food and Drug Administration-approved Phase III trials in humans – something that fuels kratom advocate claims that corporations simply want to ban a natural rival.

Susruta Majumdar, a chemist at Memorial Sloan Kettering Cancer Center, told Scientific American a compound that comes from fermented kratom, mitragynine pseudoindoxyl, may offer a substantial advance for medicine.

That kratom-derived compound blocks another opioid receptor, the delta receptor, which could indicate lower tolerance and withdrawal potential, Majumdar said. Combined with a distinct interaction with the mu receptor, that could portend a major potential step forward for prescription painkiller research.

If the DEA emergency scheduling decision takes effect, kratom's placement in Schedule I will last two or three years, pending further research to justify permanent listing or removal.

Research into Schedule I substances requires a special DEA permit and, among other security measures, installation of an expensive safe that can cost more than $10,000 – burdens lamented for years by researchers studying marijuana.

Acquiring kratom for research may become more difficult when the ban takes effect for other reasons as well. The leaf product's shelf life is perhaps a few years and the tree can't be grown in non-tropical U.S. regions, with its size making it a poor fit for greenhouses.

Overdoses involving legal and illegal opioids, including heroin, combined killed more than 28,000 Americans in 2014 alone. But despite the thought that kratom may help curb that total, Baer says there simply is insufficient evidence of kratom's safety and efficacy for it to remain legal.

"We need to answer the $75,000 question: Does kratom have a currently accepted medical use?" he says. "If you talk to any researcher at this point, they may say the substance has potential for medicine, but that doesn't get us over the threshold for determining if kratom has a currently accepted medical use."

Though it may be tempting for advocates to sense a victory in kratom not becoming illegal Friday, Baer says the DEA won't be swayed by the influx of calls it has received.

"We can't rely upon public opinion and anecdotal evidence. We have to rely upon science," he says.

Update, 3:30 p.m.:

David Kolovson, a spokesman for Rep. Mark Pocan, D-Wis., tells U.S. News that Pocan spoke with DEA Acting Administrator Chuck Rosenberg on Friday, and that Rosenberg indicated the decision to ban kratom will be postponed while the agency opens a modified public notice and comment period.

Rather than enact the ban in the immediate future, "it appears the DEA will instead open up a modified comment process before a final decision will be made," Kolovson says. "While we do not know the exact timing or details of the new comment period for kratom, Acting Administrator Rosenberg assured Congressman Pocan that we will find out more in the near future."

The number of days that would be included in the modified public comment period is not yet clear, Kolovson says.