It's not the first time a plant - or a substance sold in colorful packages at smoke shops - has raised a ruckus. But unlike marijuana or bath salts, local stores are legally able to sell kratom (pronounced KRAYT-um).
Retailers and users of the drug say it's a mild stimulant like caffeine and a painkiller that can help addicts transition away from heroin or prescription narcotics.
Local police, the Food and Drug Administration and the Drug Enforcement Administration disagree. They say it's a drug with no legitimate medical use. They say that it's being abused, it's addictive and it has harmful side effects.
Kratom comes from leaves of a tree native to Thailand. It's often sold in capsule form, but some users make tea from the leaves or chew the leaves.
Depending on the dose, it can work as a stimulant, a painkiller or similar to an opiate. But "high" or "low" doses vary from person to person, according to sources interviewed for this story.
Last month, the FDA took a step to crack down on imports of the drug. The FDA told its field agents they could detain shipments of certain products that "have been found to contain kratom."
The agency provided a "red list" of several companies in Canada, Indonesia and Malaysia whose shipments can be blocked from entry into the U.S.
Local sellers TBCO - owner of Big Smoke and Tobacco Connection stores - and Lux Botanica said the FDA action hasn't affected their supply of kratom products.
"As far as our sales go, they're fine," said Ed Franklin, marketing manager for TBCO.
Who buys the drug?
"A lot of people seeking relief from chronic back pain and stuff like that use it and say it's great for them," Franklin said.
The company has advertised its kratom inventory on letter boards outside of stores.
Franklin said the decision to stock kratom hinged on a statement from the Idaho State Board of Pharmacy "that they didn't consider it a problem. ... Otherwise, we wouldn't have brought it in."
But the pharmacy board's executive director, Mark Johnston, said that's not quite what the board meant when it addressed questions from retailers wondering whether kratom is similar to the controlled substance known as "spice." The board answered that kratom "is not a controlled substance or a prescription drug in the state of Idaho," he said.
Johnston said during an interview that kratom has been on the market for 20 years.
"The FDA's only recourse is to prove something isn't safe and remove it," he said.
What little information scientists have about kratom's effects on people - whether its users get addicted, hallucinate or suffer health consequences - is anecdotal.
An article in the Journal of Forensic Sciences in October 2012 talked about a 17-year-old male found dead in his bed, with a history of heroin abuse and self-medicating with kratom. The medical examiner said the cause of death was "possible kratom toxicity," based on lab results that showed some kratom use.
Jermaine Galloway, alcohol compliance officer for the Boise Police Department's community policing unit, said he started noticing kratom for sale at convenience stores a couple of years ago.
Galloway has never run into someone he knew for certain was high on kratom or seen a confirmed overdose. But police don't test for the chemical when they conduct drug or alcohol testing, he said, so it's impossible to know whether someone has used it.
"The way we look at it, drugs are drugs," he said. "They're harmful, they're scary, they're addictive and they could ruin lives."
Galloway said he hears people are using it to get a "legal high," not as an herbal painkiller. One woman told him she would take it before getting tattoos, for a mellow high.
Local DEA agent Bill Lutz said kratom is considered addictive, but he doesn't know of any fatal overdoses.
"As we become more and more exposed to it and it becomes more and more popular, I think the true telltale signs of its potential for abuse will show up," he said. "What we're hearing on the street is folks on rehab or probation ... are taking it because it's not showing up" on drug tests.
His basic concern with kratom, as an unregulated and unmonitored chemical substance, is, "What are you really ingesting?"
The owner of Lux Botanica - who did not want his name used because of controversy over the drug - said he was addicted to painkillers for more than a decade before quitting almost four years ago. He discovered kratom after getting clean, he said, adding that it is now harder for him to stop drinking coffee or caffeinated drinks than it is to stop using kratom.
He started selling kratom through a website he launched last fall.
"The FDA red alert does have caveats in there - that it is nonbinding - but I suspect it will have an effect. Supplies will dry up," he said.
He welcomes regulation to keep minors from buying kratom. That's an unwritten rule most retailers follow, he said, and one he tries to enforce by checking photo IDs when customers pick up orders.
He thinks opiate and opioid addicts could benefit from kratom as "an extra tool when they're fighting for that sobriety. ... We should be embracing this as part of the solution to this heroin problem we have in this country."
Galloway thinks that's a bad idea.
"There's other ways, through your doctor, through certified medical personnel, for getting off of addiction than going to a different drug and saying it's the lesser of two evils," he said. "Obviously, if you have an addiction to one (drug), you're just going to get an addiction to another."
Audrey Dutton: 377-6448, Twitter: @IDS_Audrey