KUSA- The University of Colorado Hospital says it's seen eight new patients with bad reactions to synthetic marijuana products known as "Spice" and "Black Mamba."

The hospital says four patients were admitted Tuesday night and another four came in Wednesday morning.

"The availability and the ability to smoke it without being detected are two really, really attractive features of using this drug. So, that's why I think a lot of people use it," said Dr. Christopher Hoyte, assistant professor, department of emergency medicine at the University of Colorado Hospital.

Roughly 40 patients with reactions to the drug have visited the hospital ER in the last two weeks. Some patients have been unconscious and unable to breathe on their own after ingesting Black Mamba or Spice.

"Patients who have come into our emergency department have had to be intubated, placed on ventilators to help them breathe because they are unable to breathe for themselves. They've become so agitated that they've jumped out of cars, people were jumping out of cars hurting themselves so this batch of synthetics is very, very toxic especially in comparison to normal marijuana," said Hoyte.

Synthetic marijuana products are illegal, but the makers are finding creative ways to skirt the laws.

"What the smart street chemists are doing is that they're changing the chemical structure of the molecule to try to put it in a category that's outside of the class of drugs that's illegal, so by changing the structure they're making it a 'legal substance,'" said Hoyte.

Because the composition of the drug is always changing, doctors are not sure what's causing the bad reactions.

"Either it's a new cannabinoid that hasn't been discovered yet or it might be a contaminate in the batch that people are using," said Hoyte.

The state health department has asked the Centers for Disease Control and Prevention to assist in its investigation.