These days, K2 goes by a variety of names. It contains plant material and several chemicals that mimic the effect of THC. Casey Bortnick has more about synthetic marijuana.

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"K2 is considered to be a couple of things… It’s basically what it says, one is an incense, one is a potpourri," said Theresa Dyer, owner of Look Ah Hookah smoke shop.

It's what this "incense" is being used for....

"The intent is to smoke it," said Dr. Timothy Wiegand, a toxicologist.

That has doctors concerned.

"The catch is the incense had cannabinoid, a chemical that acts like THC dissolved and sprayed on," said Dr Wiegand.

THC is the compound in marijuana that gets its users high. K2, now marketed under various names, contains plant material and several chemicals that mimic this effect. Wiegand says this synthetic product is much more dangerous.

"Seizure is a common side effect of K2," said Dr. Wiegand.

Smoking K2 can increase a person’s heart rate and blood pressure, leading to chest pain, vomiting, twitching, and thoughts of suicide.

"We've had a couple of really unfortunate individuals who have struggled with throat disorder, hallucinations and with what we'd call psychosis for months after use," said Dr. Wiegand.

Wiegand says in the last year, more than a thousand people in Upstate New York, many of them teenagers, have been hospitalized after smoking K2. So why is it still legal? The answer is on the label.

"Not sold for human consumption," Dr. Wiegand explained.

Since the product isn't marketed as something that should be smoked to get high, it skirts the current drug laws.

U.S. Congressman Tom Reed supported legislation adding K2 to a list of banned substances. He says fighting this battle through legislation is tricky.

"As we define one of these substances the bad guys are right out ahead of us trying to reformulate the recipes. And we keep chasing them," said Congressman Reed.

Employees at the smoke shop are instructed to ask for ID and to turn away customers who say they intend to smoke K2.

"If you keep discussing it we're going to have to ask you to leave," said Dyer.

Theresa Dyer believes those under 18 are getting the product from convenience stores that follow more relaxed guidelines. Either way, once it leaves the store, Dyer says it's the buyer's choice what they do with it.

"There’s a lot of products that are regular everyday items but people use it for the wrong reasons," said Dyer.