Cape Town ? Demi Lovato reportedly refused to disclose which drug caused her to overdose when paramedics responded to a 911 call at her home. TMZ first reported Demi overdosed on heroin, however sources confirmed to Daily Mail that she was given Narcan when she was found ? Narcan is a medication used to reverse the effects of an opioid overdose. An insider revealed to Us Weekly, Demi?s friends had the medication on hand in case something like this would happen.