Both of those illicit fentanyl and carfentanil are really risky opioids that will lead to a quick overdose and Dying when abused, but carfentanil is much more potent than fentanyl. Multiple doses of your anti-overdose drug naloxone (Narcan) will not be effective to reverse an overdose. Carry on studyingRe: Definitely Freaked Out!! Fentanyl OD or W/