It shares the name of the second-highest mountain on earth.

It’s perfectly legal to purchase, and for the younger-than-18 age group, it’s easier to buy than tobacco.

It’s called K2, and it’s available at most tobacco shops and, likely, a convenience store near you.

It comes in several flavors and strengths, including “Bubblegum,” “Citron” and “Summit.” It ranges in price from $30 to $40 for a 3-gram packet that looks like it might have a baseball card and a flat piece of gum inside, to $3,300 for a kilogram.

Police compare those prices to high-grade “hydro” marijuana — much more expensive than street-corner marijuana that comes from Mexico. Users say it gives a high similar to marijuana but the good feelings don’t last as long. Some researchers say it isn’t the blended herbs that cause the highs and lows of the product called K2; it’s the chemicals sprayed on the potpourri-like substance that people are smoking in pipes.

The chemicals cause the high — and sometimes the ugly side effects that sent Denton police and paramedics to two homes late last month when young adults were struggling to breathe, shaking and thinking they were going to die.

“They don’t know what they are putting in their bodies. They don’t know what they are buying,” said Denton Narcotics Sgt. Brad Curtis. “We’ve run across it when we executed search warrants and seen it mixed with marijuana. It’s mostly the younger crowd. It is not sold as a tobacco product, so the age limit for buying or using tobacco products does not apply.”

No law exists that prohibits it — at least not in Texas — and nothing regulates it, Curtis said. The tobacco shops, head shops and Internet sites all stress it is not for human consumption. But at $30 to $40 for a 3-gram package (think of the contents of three packets of sugar), people who buy it for its aromatic smell are purchasing a really expensive bowl of potpourri.

And the name, of course, is a clue.

On April 27, a man in the 3000 block of Quail Creek Road called 911. His 17-year-old girlfriend was “freaking out,” he said. She was lying on the floor in a daze, shaking and gasping for breath. Denton paramedics talked to her and her boyfriend. They learned she had been smoking K2 mixed with “spike,” according to the police report. The pair said they had bought the K2 at a downtown smoke shop called High Times. They’d been smoking it for about a month, but this was the first time they mixed the two. She was admitted to a hospital.

Lt. David Scott, who supervises the narcotics unit of the Denton County Sheriff’s Office, said he believes the spike referred to may have been something as simple as an energy drink.

“There is something we refer to as synergy,” Scott said. “It’s the way substances react together. Someone can have a beer, and that’s OK. They can have some kind of drug, and that might not have hurt them alone, but mixed with the alcohol it can be lethal.”

K2 is sprayed with a chemical that is not THC, the main psychoactive substance in marijuana. The chemical fools the brain’s THC receptors into thinking it is THC. The chemical is not illegal.

Scott said that mixing the pseudo THC with an energy drink that contains large amounts of sugar and caffeine could cause a bad synergic reaction.

“You mix that hallucinogenic with all that sugar and all that caffeine, and it could shut you down,” he said.

One day after the 17-year-old girl’s reaction, paramedics and police responded to a similar call in the 8000 block of Clear River Lane.

A woman said a teenage boy visitor to her house was in severe distress, having breathing difficulty while showing signs of intoxication with lethargy and slurred speech. He and her son had been to church, she said, and the visitor fell ill shortly after they arrived at her house.

An officer and an ambulance responded. Paramedics hooked the patient to an IV and began talking to him about what he might have ingested. Some boys at church had given him some K2, he said. He smoked it.

The teen’s mother, who said she is a police officer with another agency, lived a half-hour’s drive away. She was contacted. She told the friend of the teen to not talk to police or paramedics.

According to a police report, she told the paramedics to unhook the IV. She didn’t want him treated and she wanted the ambulance to leave. No one had her permission to treat her son, she said, and she wasn’t giving that permission.

The woman told the police officer to leave. She knew her rights, she said. What her son had ingested was legal.

“It’s just potpourri,” she said, according to the report. “Leave him alone.”

The officer told the irate mother that he could not leave her son in his current condition. Her son couldn’t walk, he told her. He was too impaired to be left without medical attention, and besides, the boy was ill and scared and wanted to go to the hospital, the report states.

The officer refused to leave and stayed with the boy until the mother arrived. She would seek medical attention if her son needed it, she told the officer, and drove away with him.

Denton fire Battalion Chief Charles Goodman, who supervises the medical division of the fire department, said paramedics who have responded to such K2 reactions said patients showed signs of extreme intoxication, with breathing difficulties, increased pulse rate and blood pressure. They were nauseous and vomiting.

“One patient stated the K2 had been laced with some other chemical but they didn’t know what. That is scary,” Goodman said. “What are these people thinking? From what I have read on the Internet, it is not clear what chemicals are used to produce the product in the first place and then they add an additional unknown ingredient.”

The male victim could not be reached for comment.

The teenage girl said she had given a television interview that focused too much attention on her, and talking about her experience upset her. She refused further comment.

On Internet sites, numerous people have written about their experiences smoking K2. Some extol its virtues as a legal high. Others say that, after having a terrifying experience, they will never smoke it again. No one mentioned actually using it as incense.

Jimmy Hooper runs High Times, the tobacco shop just west of the Square. The glass storefront has prominent signs prohibiting anyone younger than 18 from entering.

Hooper didn’t want to talk about K2, which was displayed in a glass case near the cash register.

“The label says it is incense,” he said. “I sell it as incense. That’s all I know about it, and that’s all I’m going to say about it.”

DONNA FIELDER can be reached at 940-566-6885. Her e-mail address is dfielder@dentonrc.com.