Each illicit fentanyl and carfentanil are very perilous opioids which will cause a quick overdose and Dying when abused, but carfentanil is much more potent than fentanyl. Various doses with the anti-overdose drug naloxone (Narcan) is probably not effective to reverse an overdose. Go on looking atRe: Truly Freaked Out!! Fentanyl OD or W/D, Not sure