DENVER (CBS4) – After recent crackdowns on Spice, a new drug called kratom is filling the void left on store shelves as the next “legal high.”

Kratom comes from a tree leaf in Southeast Asia and has been used for years. It is now growing in popularity in Colorado.

Drug addiction experts say just because kratom is legal that doesn’t mean it is safe.

Currently, kratom is banned in a number of countries in Asia and Europe. Indiana is the only state in the U.S. that has banned kratom, but you wouldn’t always know that from the way people are selling it.

CBS4 spotted kratom for sale on a Denver-based website and sent an undercover producer to buy some. The seller, who identified himself as Jeremy, met CBS4 in Denver’s Capitol Hill neighborhood.

“The super elephant is actually my most potent and euphoric,” Jeremy said. “I’d recommend starting with three or four of them.”

For $10 Jeremy provided five capsules of “super elephant” and 10 capsules of “Borneo Red” in what he called a “first-time customer special.”

CBS4 found Jeremy through his website, where it repeatedly warns kratom is “not for human consumption” — only for professional research, aromatherapy or ornamental uses. But in person, Jeremy quickly went off script and told our producer how to consume them.

“I have them in capsules so you can just wash them down. I recommend orange juice is the best — it releases the alkaloids and actually makes it more potent,” he said.

The seller also offered kratom in powder form. It is also commonly sold as a liquid or steeped in a tea.

But just how potent, addictive or dangerous is kratom? Nobody knows exactly.

Todd Bunger researches emerging drugs at Arapahoe House, a local drug treatment center. “If they are saying it’s not meant for human consumption maybe you ought to take that seriously.”

The Drug Enforcement Agency calls kratom a “drug of concern.” It is described as producing both stimulant and sedative effects.

According to the DEA, in the United Kingdom kratom is referred to as an “herbal speedball.” Bunger says that appears to be an accurate description “A speedball is actually a reference to a cocaine heroin mix.”

Bunger says he understands kratom acts very much the same way as a singular drug. “It initially gives you a rush and then mellows you out.”

Kratom users told CBS4 it provides a stimulant euphoric effect, can help with anxiety, and can be used to wean drug users off stronger opiates.

Kratom is unregulated in Colorado, it is not approved by the FDA, but it has not been outlawed.

“It is concerning because the perception of legality also has a perception of safety,” Bunger said. He went on to say because it is unregulated, nobody really knows what is in the kratom products for sale in Colorado, or what the long term risks may be.

But a mother in Texas has her suspicions. Patty Smith said she thought her daughter was having unusual mood swings. When she discovered 80 empty bottles of kratom she said she realized her daughter had a serious problem. “I’m sure this isn’t all, but this is about $1,600 worth of product in this bag.”

Smith went on to say her daughter was taking two to three bottles of Kratom every day before they had a family intervention and took their daughter for medical help.

“Ultimately I was afraid it was going to kill her, or ruin her health completely,” said Smith. “I was afraid in some way this could eventually kill her.”

CBS4 also purchased kratom from a local chain of shops which sells the product in each of its seven stores.

Two clerks told CBS4 they routinely ingest kratom. One employee demonstrated taking a liquid version while CBS4 was there.

“It puts you in a whistle while-you-work mood,” one employee said.

The clerks told CBS4 that kratom was no more dangerous than your morning brew.

“It’s almost like coffee but it’s better than coffee,” the other employee said.

The female clerk said she had been using it consistently for two years.

“I just feel super alert, my mind if all focused in one place and all my fatigue is gone.”

Sellers say the worst that can happen is an upset stomach if you take too much. Others claim it can lead to serious addiction.

In an unguarded moment, our Denver street seller conceded you can get addicted to kratom.

“It does have a mild addictive affects but no worse than caffeine,” they said.

That Kratom seller later told CBS4 he puts a disclaimer on it for liability reasons. He extolled its benefits but said more research should be done to find out both the benefits and the risks.

“Kratom is definitely addictive,” said Jeremy, “but no more so than coffee. Besides the addictive quality of the herb, I haven’t seen many other negatives.”

“I believe in taking personal responsibility” he said, “Caffeine, nicotine, food, gambling, alcohol, video games and the Internet are all legal in the state of Colorado.”

He went on to say that over a long period of time, kratom use can lead to “light” withdrawal symptoms. He said the withdrawal is similar to quitting caffeine after heavy daily use.

In an extended discussion, Jeremy said “I really wish that more research would go into this herb so we could know for certain all of the dangers and confirmed benefits that go along with the kratom leaf.”