Synthetic marijuana may be to blame in three deaths and 75 hospitalizations in Colorado, CNN reports. The Colorado Department of Public Health and the Centers for Disease Control and Prevention are investigating whether the drugs caused the illnesses, which sent people to hospitals in Denver and Colorado Springs beginning in late August.

Synthetic marijuana, commonly known as K2 or Spice, is a mixture of herbs, spices or shredded plant material that is typically sprayed with a synthetic compound chemically similar to THC, the psychoactive ingredient in marijuana. K2 is typically sold in small, silvery plastic bags of dried leaves and marketed as incense that can be smoked.

Investigators hope to determine whether all the patients became ill after taking the same product or different products. Dr. Tista Ghosh, interim chief medical officer for the state, said in a statement, “Don’t wait for the results of this investigation. If you have synthetic marijuana, stop using it and destroy it.”

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.

The onset of the drug is three to five minutes, and the duration of the high is one to eight hours. In addition to physical signs of use, users may experience severe paranoia, delusions, hallucinations and increased agitation. Its long-term effects are unknown.