CASTLE ROCK — Kratom, an herbal extract derived from a tree that grows on the other side of the world, has been touted for its calm, soothing effects on those who consume it.

But it is causing some agitation in Colorado as the extract — seen by many as a safe, natural alternative to addictive and sometimes lethal opioid painkillers — grows in popularity.

Castle Rock is one of the first communities in Colorado to take a deep dive on Mitragyna speciosa, the formal name for kratom. The town imposed a six-month ban on the licensing of any new kratom shops last December while it works out a set of rules. Kratom is largely unregulated in the country and banned in six states.

Last week, Castle Rock hosted an open house to get feedback from the public on how it should regulate the product, which is largely sold in powder and capsule form at gas stations and head shops.

Some attendees at the meeting said Castle Rock’s proposed approach, which would do little more than set a minimum age of 18 for the purchase of kratom, could become a model for other cities and towns in Colorado.

“Regulation is badly needed,” said Joy Awakuni, a Colorado Springs resident who turned to kratom seven years ago after pharmaceutical medications did little to help her with pain and other health problems. “Castle Rock is doing it right — some communities are banning it.”

Denver banned the sale of kratom for human consumption a couple of years ago, citing a warning from the U.S. Food and Drug Administration that the supplement should not be used by consumers.

“There are no FDA-approved uses for kratom and the FDA does not allow kratom to be imported into the U.S. as a consumable commodity,” the Denver Department of Public Health and Environment says on its website.