Emergency rooms in Denver, Colorado reported a surge in visits related to synthetic marijuana in the late summer and early fall, according to the Los Angeles Times.
Experts say similar patterns may emerge in other parts of the country.
Between August 24 and September 19, area emergency rooms saw 263 patients, mostly young men, with symptoms related to synthetic marijuana. Most patients were treated in the emergency room, but seven were admitted to intensive care units.
In a letter in this week's New England Journal of Medicine, Dr. Andrew A. Monte of the University of Colorado School of Medicine writes synthetic marijuana appears to be growing more potent. "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," he wrote.
Synthetic marijuana is sold under names including K2, Spice and Black Mamba. It is made with dried herbs and spices that are sprayed with chemicals that induce a marijuana-type high when smoked, the article notes. The products are widely available, despite laws prohibiting them.
"These substances are not benign," Monte said. "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."
In September, the Colorado Department of Public Health and the Centers for Disease Control and Prevention announced they were investigating whether three deaths and 75 hospitalizations were caused by synthetic marijuana.
Short-term effects of using synthetic marijuana include loss of control, lack of pain response, increased agitation, pale skin, seizures, vomiting, profuse sweating, uncontrolled/spastic body movements, elevated blood pressure, heart rate and palpitations.