Boston banned the use, sale, or purchase of synthetic marijuana, which has been linked to a nationwide rise in poisonings and overdose deaths, on Aug. 14, 2015.

The drug, also known as “K2” or “spice,” is not made from the marijuana plant but is a mix of plant material sprayed with a variety of chemicals intended to provide a high similar to that resulting from marijuana smoking.

Medical experts say it is a far more potent drug that provokes erratic behavior. The U.S. Centers for Disease Control in June warned that calls to poison control centers and deaths from overdoses of the drug were on the rise.

A 2012 U.S. law attempted to ban the drug nationally, but its makers have steadily tweaked the chemical cocktails they use in order to skirt that ban.

“This ordinance will give our law enforcement officials the authority to enforce not just the sale and possession of the synthetic marijuana found in our stores today, but all types of synthetic chemical compounds produced in the future,” Boston City Councilor Frank Baker, who proposed the ordinance, said after it was signed by Mayor Marty Walsh.

The sale, possession, or distribution of the drug will be penalized with a $300 fine, Boston officials said.

Rising use of synthetic marijuana, which is sold in gas stations and convenience stores and sometimes labeled as incense, has prompted concern among police and policymakers across the United States.

New York police this month launched a crackdown on the drug they called “weaponized marijuana,” but came under criticism after it was revealed that a video intended to show the drug’s extreme effects, depicting delirious naked men ranting in public, actually featured users of other drugs.

Boston’s new measure comes a week after two pro-marijuana groups submitted potential ballot items that could put to voters the question of whether to legalize marijuana across the state of Massachusetts. Walsh, a recovering alcoholic, has said he opposes the idea of legalizing marijuana.