Emergency rooms treating patients who have taken the synthetic drug K2 are dealing with multiple challenges, according to The Wall Street Journal.

Some patients are agitated and violent, while others may lapse into unconsciousness. Patients who have taken K2 often exhibit unpredictable behavior. They may be calm one moment, and then become explosively angry. Most hospitals are not equipped to test for K2, and no antidote exists.

Packages labeled K2 may contain hundreds of chemicals, many of them not well understood, the article notes. Earlier this month, New York City emergency rooms reported seeing 130 patients suspected of taking the drug.