Until recently, synthetic marijuana was known to only have triggered just a handful of emergency room admissions. However, medical experts warn that a sudden surge in illnesses at hospitals located in Denver could be a sign that similar outbreaks may pop up in other parts of the country.

The dangers of synthetic marijuana, also known as incense, potpourri, and herbal smoking blend, are clear. It is a mixture of dried herbs and spices sprayed with chemicals that create a marijuana-like high when smoked. But unlike organic marijuana, these agents can cause much more severe symptoms.

Despite laws prohibiting the sale of synthetic marijuana, the products are packaged under names like Black Mamba, K2 and Spice and sold over the counter at convenience stores, reports Science 2.0.

Between Aug. 24 and Sept. 19, emergency rooms in Colorado experienced a sudden surge in admissions related to the drug, reports the LA Times. It was noted that 263 of the mostly male patients reported symptoms like altered mental status, irregular heart beat and seizures, while approximately 10 percent required intensive care treatment.

In an editorial published Wednesday in the New England Journal of Medicine, experts warned that the use of synthetic cannabinoids appears to be growing, which could lead to more outbreaks of illness and possible deaths.

"Although the effects of exposures to first-generation synthetic cannabinoids are largely benign, newer products have been associated with seizures, ischemic stroke and cardiac toxicity, possibly due to potency," the study reads.

"These substances are not benign," wrote the paper's lead author, Dr. Andrew Monte, an assistant professor in emergency medicine and medical toxicology at University of Colorado School of Medicine.  

"You can buy designer drugs of abuse at convenience stores and on the Internet. People may not realize how dangerous these drugs can be -- up to 1,000 times stronger binding to cannabis receptors when compared to traditional marijuana." Synthetic marijuana can also lead to delirium, seizures and strokes.

"Synthetic marijuana is illegal under DEA law, but companies that make it are a step ahead with new chemicals and packaging on standby all the time." said Monte. He added that there has been a significant increase in the use of synthetic marijuana in the last 5 years and that, "Outbreaks like this are likely to keep happening."

He went on to say, "We need better testing to identify these substances, open communication with public health officials when outbreaks occur and we need to make sure physicians ask patients the right questions about their drug use."

The Denver outbreak ended abruptly after only 10 cases were reported at the same hospitals from Sept. 13 to Oct. 25. 

However, last week a New Orleans convenience store located in Alexandria lost its alcohol and tobacco permits state agents found more than 560 packages of synthetic marijuana being sold at the store during a Nov. operation.

The Louisiana Office of Alcohol and Tobacco Control agency suspended the store's alcohol and tobacco permits on Jan. 15, reports the Associated Press.