Products containing the hemp derivative CBD are gaining popularity in Minnesota, even though their ingredient lists can be unreliable, their effectiveness is poorly studied, and some sales for medicinal purposes might be crimes in this state.

Fatigued by pain and exhausted by anxiety, customers are flocking to shops — and some clinics and pharmacies — to try CBD products that are supposed to provide the soothing benefits of marijuana without the trippiness.

"Seriously, I really go by this stuff," said Barb Kuehn, 67, an Oak Park Heights woman who receives CBD drops and ointments from her chiropractor for arthritis. "I can't go without having it in my house."

Retailers such as Nothing But Hemp and Minnesota Hempdropz are part of an industry that has expanded in just months from two specialty stores in the Twin Cities to as many as a dozen by spring.

CBD oils, ointments, inhalants and gummies have, however, emerged in a regulatory and legal vacuum: Federal and state laws permit manufacture of products using hemp — a variant of marijuana that can't produce a high — but don't allow them to be promoted for unproven medical cures or benefits.

The CBD surge has in many ways raced past the ability of regulators to police sales, said Cody Wiberg of the Minnesota Board of Pharmacy. He worries they are treated like consumer products even though CBD behaves like prescription drugs that his agency regulates.

"CBD is pharmacologically active," he said. "It acts like a drug. It is metabolized in the liver by the same enzymes that metabolize 50 to 60 percent of the drugs on the market."

CBD, short for cannabidiol, is one of the two primary compounds in marijuana that affect the human nervous and endocannabinoid systems. The other is tetrahydrocannabinol, or THC, which produces the drug's delirious effects. Hemp is a version of marijuana that is grown with little or no THC.

Minnesota's medical marijuana program permits certified patients with chronic pain and 13 other conditions to receive cannabis products containing varying levels of CBD and THC from two state-sanctioned distributors.

That is distinct from the consumer CBD market, and yet the customers are sometimes the same, said Abbie Herkenhoff, co-owner of Minnesota Hempdropz stores in Maplewood and Columbia Heights. Many of her customers are frustrated by pains they can't shake or tired of the opioid painkillers that can be potent and addictive.

"We have a lot of people who have been on opioid medication for a decade and are just sick of it," Herkenhoff said.

The market for CBD took off after Congress passed a 2018 farm bill that distinguished hemp from marijuana, meaning it was no longer an illicit controlled substance.

But the lack of regulation for CBD since then has created problems, such as concerns about inaccurate labels and ingredient lists. When officials in Crow Wing County came across a product marketed as a CBD "medical" cigar, they sent it to a state lab for testing and found that it contained half the CBD listed on the packaging.

University of Minnesota biologists tested a CBD vaping product and found it contained a slightly higher level of THC than permitted under the law. U Prof. George Weiblen said he suspects that more products have too much THC, especially those from hybrid versions of hemp and marijuana plants. He worries that problems could hurt the broader industrial hemp market.

"There's nothing regulating the labeling of these products," he said. "That's part of the problem. The other problem is that these drugs, they interact with our nervous systems in complex ways that we're only beginning to understand."

Lower-quality methods of extracting CBD from hemp have left products with traces of other chemicals. The U.S. Food and Drug Administration's commissioner responded last week with calls for tougher oversight. The agency also warned three manufacturers about promoting their CBD products for unfounded medical benefits.

Facing this regulatory confusion, state Sen. Karla Bigham, D-Cottage Grove, has introduced bills to require accurate labeling of CBD products and to protect the growing hemp industry. The state has 256 hemp farmers and 130 processors.

Bigham approaches the issue as a CBD believer. She broke her foot clinging to the leash of her dog when it took off after another animal, and has since had three surgeries. She started taking CBD in January, and her stiffness and pain disappeared.

"I was able to snowshoe on my 40th birthday," she said. "I can run on my treadmill."

Still, research on CBD is sparse. The only FDA-approved drug containing CBD is Epidiolex, which treats epileptic seizures. A 2010 study at the U found that a synthetic cannabinoid controlled pain in mice, but the author said the current commercial use of CBD is far beyond what science has proved.

"You can't get away from CBD. Now my co-op is selling it," said Kalpna Gupta, a U professor.

Many retailers are mindful of the confusion. Walgreens announced this week it would sell CBD topical ointments and creams. Minneapolis-based Target said in a statement that it has not added CBD products despite consumer interest and that it will continue to monitor the debate and the FDA's plans.

Allina Health, a hospital and clinic network in the Twin Cities, sells CBD products at its Penny George Institute for Health & Healing, but only to patients who have received a doctor's recommendation.

Small retailers say they take steps to police themselves. Minnesota Hempdropz sells only products by manufacturers that release batch test results to ensure the proper ingredients. Nothing But Hemp requires testing by third-party labs without a direct financial interest.

Retailers are careful when talking with customers, said Steven Brown, owner of the Nothing But Hemp stores. While some studies have backed CBD for anxiety, pain and inflammation, retailers can't make other claims. "We can tell people what other people use it for. But we can't say this is going to be the cure-all."

The anecdotes are compelling, though. Brown said CBD helped him overcome anxiety of public speaking and eliminated his wife's migraines. And while he can't say it treats Parkinson's disease, he can relay the story of a man who bought a CBD product and felt tremors go away a half-hour later.

"That's a true story," he said. "I can say that. It doesn't mean its going to work for everyone."

Even so, regulators are concerned about the sales pitches. An official with the Hennepin County Public Health Department told a vendor in the Eden Prairie Shopping Center recently to stop selling CBD water and gummy products because the packaging didn't specify legal THC levels.

Wiberg said the pharmacy board isn't investigating suspect claims or CBD products that might meet the state definition of drugs. The costs are too great, he said, and would go to waste if legislators suddenly approved CBD products. But the board will investigate consumer complaints.

"CBD is a potentially beneficial product," Wiberg said, but right now we're in what I would call the wild, wild West phase, or maybe even the snake oil phase."