Naloxone reverses an opioid overdose if administered in time. (WTTW News)

The key culprit appears to be the widespread availability of the powerful synthetic opioid fentanyl.

Why is Puerto Rico sending addicts from the island to Chicago? WBEZ reporter Odette Yousef explains the story.

U.S. Sen. Mark Kirk expands efforts to fight heroin overdoses in Cook and surrounding counties.